001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.lang3;
018
019import java.io.UnsupportedEncodingException;
020import java.nio.charset.Charset;
021import java.text.Normalizer;
022import java.util.ArrayList;
023import java.util.Arrays;
024import java.util.HashSet;
025import java.util.Iterator;
026import java.util.List;
027import java.util.Locale;
028import java.util.Objects;
029import java.util.Set;
030import java.util.function.Supplier;
031import java.util.regex.Pattern;
032
033import org.apache.commons.lang3.function.Suppliers;
034import org.apache.commons.lang3.function.ToBooleanBiFunction;
035import org.apache.commons.lang3.stream.LangCollectors;
036import org.apache.commons.lang3.stream.Streams;
037
038/**
039 * Operations on {@link java.lang.String} that are
040 * {@code null} safe.
041 *
042 * <ul>
043 *  <li><b>IsEmpty/IsBlank</b>
044 *      - checks if a String contains text</li>
045 *  <li><b>Trim/Strip</b>
046 *      - removes leading and trailing whitespace</li>
047 *  <li><b>Equals/Compare</b>
048 *      - compares two strings in a null-safe manner</li>
049 *  <li><b>startsWith</b>
050 *      - check if a String starts with a prefix in a null-safe manner</li>
051 *  <li><b>endsWith</b>
052 *      - check if a String ends with a suffix in a null-safe manner</li>
053 *  <li><b>IndexOf/LastIndexOf/Contains</b>
054 *      - null-safe index-of checks
055 *  <li><b>IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut</b>
056 *      - index-of any of a set of Strings</li>
057 *  <li><b>ContainsOnly/ContainsNone/ContainsAny</b>
058 *      - checks if String contains only/none/any of these characters</li>
059 *  <li><b>Substring/Left/Right/Mid</b>
060 *      - null-safe substring extractions</li>
061 *  <li><b>SubstringBefore/SubstringAfter/SubstringBetween</b>
062 *      - substring extraction relative to other strings</li>
063 *  <li><b>Split/Join</b>
064 *      - splits a String into an array of substrings and vice versa</li>
065 *  <li><b>Remove/Delete</b>
066 *      - removes part of a String</li>
067 *  <li><b>Replace/Overlay</b>
068 *      - Searches a String and replaces one String with another</li>
069 *  <li><b>Chomp/Chop</b>
070 *      - removes the last part of a String</li>
071 *  <li><b>AppendIfMissing</b>
072 *      - appends a suffix to the end of the String if not present</li>
073 *  <li><b>PrependIfMissing</b>
074 *      - prepends a prefix to the start of the String if not present</li>
075 *  <li><b>LeftPad/RightPad/Center/Repeat</b>
076 *      - pads a String</li>
077 *  <li><b>UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize</b>
078 *      - changes the case of a String</li>
079 *  <li><b>CountMatches</b>
080 *      - counts the number of occurrences of one String in another</li>
081 *  <li><b>IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable</b>
082 *      - checks the characters in a String</li>
083 *  <li><b>DefaultString</b>
084 *      - protects against a null input String</li>
085 *  <li><b>Rotate</b>
086 *      - rotate (circular shift) a String</li>
087 *  <li><b>Reverse/ReverseDelimited</b>
088 *      - reverses a String</li>
089 *  <li><b>Abbreviate</b>
090 *      - abbreviates a string using ellipses or another given String</li>
091 *  <li><b>Difference</b>
092 *      - compares Strings and reports on their differences</li>
093 *  <li><b>LevenshteinDistance</b>
094 *      - the number of changes needed to change one String into another</li>
095 * </ul>
096 *
097 * <p>The {@link StringUtils} class defines certain words related to
098 * String handling.</p>
099 *
100 * <ul>
101 *  <li>null - {@code null}</li>
102 *  <li>empty - a zero-length string ({@code ""})</li>
103 *  <li>space - the space character ({@code ' '}, char 32)</li>
104 *  <li>whitespace - the characters defined by {@link Character#isWhitespace(char)}</li>
105 *  <li>trim - the characters &lt;= 32 as in {@link String#trim()}</li>
106 * </ul>
107 *
108 * <p>{@link StringUtils} handles {@code null} input Strings quietly.
109 * That is to say that a {@code null} input will return {@code null}.
110 * Where a {@code boolean} or {@code int} is being returned
111 * details vary by method.</p>
112 *
113 * <p>A side effect of the {@code null} handling is that a
114 * {@link NullPointerException} should be considered a bug in
115 * {@link StringUtils}.</p>
116 *
117 * <p>Methods in this class include sample code in their Javadoc comments to explain their operation.
118 * The symbol {@code *} is used to indicate any input including {@code null}.</p>
119 *
120 * <p>#ThreadSafe#</p>
121 * @see String
122 * @since 1.0
123 */
124//@Immutable
125public class StringUtils {
126
127    // Performance testing notes (JDK 1.4, Jul03, scolebourne)
128    // Whitespace:
129    // Character.isWhitespace() is faster than WHITESPACE.indexOf()
130    // where WHITESPACE is a string of all whitespace characters
131    //
132    // Character access:
133    // String.charAt(n) versus toCharArray(), then array[n]
134    // String.charAt(n) is about 15% worse for a 10K string
135    // They are about equal for a length 50 string
136    // String.charAt(n) is about 4 times better for a length 3 string
137    // String.charAt(n) is best bet overall
138    //
139    // Append:
140    // String.concat about twice as fast as StringBuffer.append
141    // (not sure who tested this)
142
143    /**
144     * A String for a space character.
145     *
146     * @since 3.2
147     */
148    public static final String SPACE = " ";
149
150    /**
151     * The empty String {@code ""}.
152     * @since 2.0
153     */
154    public static final String EMPTY = "";
155
156    /**
157     * A String for linefeed LF ("\n").
158     *
159     * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences
160     *      for Character and String Literals</a>
161     * @since 3.2
162     */
163    public static final String LF = "\n";
164
165    /**
166     * A String for carriage return CR ("\r").
167     *
168     * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences
169     *      for Character and String Literals</a>
170     * @since 3.2
171     */
172    public static final String CR = "\r";
173
174    /**
175     * Represents a failed index search.
176     * @since 2.1
177     */
178    public static final int INDEX_NOT_FOUND = -1;
179
180    /**
181     * The maximum size to which the padding constant(s) can expand.
182     */
183    private static final int PAD_LIMIT = 8192;
184
185    /**
186     * Pattern used in {@link #stripAccents(String)}.
187     */
188    private static final Pattern STRIP_ACCENTS_PATTERN = Pattern.compile("\\p{InCombiningDiacriticalMarks}+"); //$NON-NLS-1$
189
190    /**
191     * Abbreviates a String using ellipses. This will turn
192     * "Now is the time for all good men" into "Now is the time for..."
193     *
194     * <p>Specifically:</p>
195     * <ul>
196     *   <li>If the number of characters in {@code str} is less than or equal to
197     *       {@code maxWidth}, return {@code str}.</li>
198     *   <li>Else abbreviate it to {@code (substring(str, 0, max-3) + "...")}.</li>
199     *   <li>If {@code maxWidth} is less than {@code 4}, throw an
200     *       {@link IllegalArgumentException}.</li>
201     *   <li>In no case will it return a String of length greater than
202     *       {@code maxWidth}.</li>
203     * </ul>
204     *
205     * <pre>
206     * StringUtils.abbreviate(null, *)      = null
207     * StringUtils.abbreviate("", 4)        = ""
208     * StringUtils.abbreviate("abcdefg", 6) = "abc..."
209     * StringUtils.abbreviate("abcdefg", 7) = "abcdefg"
210     * StringUtils.abbreviate("abcdefg", 8) = "abcdefg"
211     * StringUtils.abbreviate("abcdefg", 4) = "a..."
212     * StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException
213     * </pre>
214     *
215     * @param str  the String to check, may be null
216     * @param maxWidth  maximum length of result String, must be at least 4
217     * @return abbreviated String, {@code null} if null String input
218     * @throws IllegalArgumentException if the width is too small
219     * @since 2.0
220     */
221    public static String abbreviate(final String str, final int maxWidth) {
222        return abbreviate(str, "...", 0, maxWidth);
223    }
224
225    /**
226     * Abbreviates a String using ellipses. This will turn
227     * "Now is the time for all good men" into "...is the time for..."
228     *
229     * <p>Works like {@code abbreviate(String, int)}, but allows you to specify
230     * a "left edge" offset.  Note that this left edge is not necessarily going to
231     * be the leftmost character in the result, or the first character following the
232     * ellipses, but it will appear somewhere in the result.
233     *
234     * <p>In no case will it return a String of length greater than
235     * {@code maxWidth}.</p>
236     *
237     * <pre>
238     * StringUtils.abbreviate(null, *, *)                = null
239     * StringUtils.abbreviate("", 0, 4)                  = ""
240     * StringUtils.abbreviate("abcdefghijklmno", -1, 10) = "abcdefg..."
241     * StringUtils.abbreviate("abcdefghijklmno", 0, 10)  = "abcdefg..."
242     * StringUtils.abbreviate("abcdefghijklmno", 1, 10)  = "abcdefg..."
243     * StringUtils.abbreviate("abcdefghijklmno", 4, 10)  = "abcdefg..."
244     * StringUtils.abbreviate("abcdefghijklmno", 5, 10)  = "...fghi..."
245     * StringUtils.abbreviate("abcdefghijklmno", 6, 10)  = "...ghij..."
246     * StringUtils.abbreviate("abcdefghijklmno", 8, 10)  = "...ijklmno"
247     * StringUtils.abbreviate("abcdefghijklmno", 10, 10) = "...ijklmno"
248     * StringUtils.abbreviate("abcdefghijklmno", 12, 10) = "...ijklmno"
249     * StringUtils.abbreviate("abcdefghij", 0, 3)        = IllegalArgumentException
250     * StringUtils.abbreviate("abcdefghij", 5, 6)        = IllegalArgumentException
251     * </pre>
252     *
253     * @param str  the String to check, may be null
254     * @param offset  left edge of source String
255     * @param maxWidth  maximum length of result String, must be at least 4
256     * @return abbreviated String, {@code null} if null String input
257     * @throws IllegalArgumentException if the width is too small
258     * @since 2.0
259     */
260    public static String abbreviate(final String str, final int offset, final int maxWidth) {
261        return abbreviate(str, "...", offset, maxWidth);
262    }
263
264    /**
265     * Abbreviates a String using another given String as replacement marker. This will turn
266     * "Now is the time for all good men" into "Now is the time for..." if "..." was defined
267     * as the replacement marker.
268     *
269     * <p>Specifically:</p>
270     * <ul>
271     *   <li>If the number of characters in {@code str} is less than or equal to
272     *       {@code maxWidth}, return {@code str}.</li>
273     *   <li>Else abbreviate it to {@code (substring(str, 0, max-abbrevMarker.length) + abbrevMarker)}.</li>
274     *   <li>If {@code maxWidth} is less than {@code abbrevMarker.length + 1}, throw an
275     *       {@link IllegalArgumentException}.</li>
276     *   <li>In no case will it return a String of length greater than
277     *       {@code maxWidth}.</li>
278     * </ul>
279     *
280     * <pre>
281     * StringUtils.abbreviate(null, "...", *)      = null
282     * StringUtils.abbreviate("abcdefg", null, *)  = "abcdefg"
283     * StringUtils.abbreviate("", "...", 4)        = ""
284     * StringUtils.abbreviate("abcdefg", ".", 5)   = "abcd."
285     * StringUtils.abbreviate("abcdefg", ".", 7)   = "abcdefg"
286     * StringUtils.abbreviate("abcdefg", ".", 8)   = "abcdefg"
287     * StringUtils.abbreviate("abcdefg", "..", 4)  = "ab.."
288     * StringUtils.abbreviate("abcdefg", "..", 3)  = "a.."
289     * StringUtils.abbreviate("abcdefg", "..", 2)  = IllegalArgumentException
290     * StringUtils.abbreviate("abcdefg", "...", 3) = IllegalArgumentException
291     * </pre>
292     *
293     * @param str  the String to check, may be null
294     * @param abbrevMarker  the String used as replacement marker
295     * @param maxWidth  maximum length of result String, must be at least {@code abbrevMarker.length + 1}
296     * @return abbreviated String, {@code null} if null String input
297     * @throws IllegalArgumentException if the width is too small
298     * @since 3.6
299     */
300    public static String abbreviate(final String str, final String abbrevMarker, final int maxWidth) {
301        return abbreviate(str, abbrevMarker, 0, maxWidth);
302    }
303    /**
304     * Abbreviates a String using a given replacement marker. This will turn
305     * "Now is the time for all good men" into "...is the time for..." if "..." was defined
306     * as the replacement marker.
307     *
308     * <p>Works like {@code abbreviate(String, String, int)}, but allows you to specify
309     * a "left edge" offset.  Note that this left edge is not necessarily going to
310     * be the leftmost character in the result, or the first character following the
311     * replacement marker, but it will appear somewhere in the result.
312     *
313     * <p>In no case will it return a String of length greater than {@code maxWidth}.</p>
314     *
315     * <pre>
316     * StringUtils.abbreviate(null, null, *, *)                 = null
317     * StringUtils.abbreviate("abcdefghijklmno", null, *, *)    = "abcdefghijklmno"
318     * StringUtils.abbreviate("", "...", 0, 4)                  = ""
319     * StringUtils.abbreviate("abcdefghijklmno", "---", -1, 10) = "abcdefg---"
320     * StringUtils.abbreviate("abcdefghijklmno", ",", 0, 10)    = "abcdefghi,"
321     * StringUtils.abbreviate("abcdefghijklmno", ",", 1, 10)    = "abcdefghi,"
322     * StringUtils.abbreviate("abcdefghijklmno", ",", 2, 10)    = "abcdefghi,"
323     * StringUtils.abbreviate("abcdefghijklmno", "::", 4, 10)   = "::efghij::"
324     * StringUtils.abbreviate("abcdefghijklmno", "...", 6, 10)  = "...ghij..."
325     * StringUtils.abbreviate("abcdefghijklmno", "*", 9, 10)    = "*ghijklmno"
326     * StringUtils.abbreviate("abcdefghijklmno", "'", 10, 10)   = "'ghijklmno"
327     * StringUtils.abbreviate("abcdefghijklmno", "!", 12, 10)   = "!ghijklmno"
328     * StringUtils.abbreviate("abcdefghij", "abra", 0, 4)       = IllegalArgumentException
329     * StringUtils.abbreviate("abcdefghij", "...", 5, 6)        = IllegalArgumentException
330     * </pre>
331     *
332     * @param str  the String to check, may be null
333     * @param abbrevMarker  the String used as replacement marker
334     * @param offset  left edge of source String
335     * @param maxWidth  maximum length of result String, must be at least 4
336     * @return abbreviated String, {@code null} if null String input
337     * @throws IllegalArgumentException if the width is too small
338     * @since 3.6
339     */
340    public static String abbreviate(final String str, final String abbrevMarker, int offset, final int maxWidth) {
341        if (isNotEmpty(str) && EMPTY.equals(abbrevMarker) && maxWidth > 0) {
342            return substring(str, 0, maxWidth);
343        }
344        if (isAnyEmpty(str, abbrevMarker)) {
345            return str;
346        }
347        final int abbrevMarkerLength = abbrevMarker.length();
348        final int minAbbrevWidth = abbrevMarkerLength + 1;
349        final int minAbbrevWidthOffset = abbrevMarkerLength + abbrevMarkerLength + 1;
350
351        if (maxWidth < minAbbrevWidth) {
352            throw new IllegalArgumentException(String.format("Minimum abbreviation width is %d", minAbbrevWidth));
353        }
354        final int strLen = str.length();
355        if (strLen <= maxWidth) {
356            return str;
357        }
358        if (offset > strLen) {
359            offset = strLen;
360        }
361        if (strLen - offset < maxWidth - abbrevMarkerLength) {
362            offset = strLen - (maxWidth - abbrevMarkerLength);
363        }
364        if (offset <= abbrevMarkerLength+1) {
365            return str.substring(0, maxWidth - abbrevMarkerLength) + abbrevMarker;
366        }
367        if (maxWidth < minAbbrevWidthOffset) {
368            throw new IllegalArgumentException(String.format("Minimum abbreviation width with offset is %d", minAbbrevWidthOffset));
369        }
370        if (offset + maxWidth - abbrevMarkerLength < strLen) {
371            return abbrevMarker + abbreviate(str.substring(offset), abbrevMarker, maxWidth - abbrevMarkerLength);
372        }
373        return abbrevMarker + str.substring(strLen - (maxWidth - abbrevMarkerLength));
374    }
375
376    /**
377     * Abbreviates a String to the length passed, replacing the middle characters with the supplied
378     * replacement String.
379     *
380     * <p>This abbreviation only occurs if the following criteria is met:</p>
381     * <ul>
382     * <li>Neither the String for abbreviation nor the replacement String are null or empty </li>
383     * <li>The length to truncate to is less than the length of the supplied String</li>
384     * <li>The length to truncate to is greater than 0</li>
385     * <li>The abbreviated String will have enough room for the length supplied replacement String
386     * and the first and last characters of the supplied String for abbreviation</li>
387     * </ul>
388     * <p>Otherwise, the returned String will be the same as the supplied String for abbreviation.
389     * </p>
390     *
391     * <pre>
392     * StringUtils.abbreviateMiddle(null, null, 0)      = null
393     * StringUtils.abbreviateMiddle("abc", null, 0)      = "abc"
394     * StringUtils.abbreviateMiddle("abc", ".", 0)      = "abc"
395     * StringUtils.abbreviateMiddle("abc", ".", 3)      = "abc"
396     * StringUtils.abbreviateMiddle("abcdef", ".", 4)     = "ab.f"
397     * </pre>
398     *
399     * @param str  the String to abbreviate, may be null
400     * @param middle the String to replace the middle characters with, may be null
401     * @param length the length to abbreviate {@code str} to.
402     * @return the abbreviated String if the above criteria is met, or the original String supplied for abbreviation.
403     * @since 2.5
404     */
405    public static String abbreviateMiddle(final String str, final String middle, final int length) {
406        if (isAnyEmpty(str, middle) || length >= str.length() || length < middle.length()+2) {
407            return str;
408        }
409
410        final int targetSting = length-middle.length();
411        final int startOffset = targetSting/2+targetSting%2;
412        final int endOffset = str.length()-targetSting/2;
413
414        return str.substring(0, startOffset) +
415            middle +
416            str.substring(endOffset);
417    }
418
419    /**
420     * Appends the suffix to the end of the string if the string does not
421     * already end with the suffix.
422     *
423     * @param str The string.
424     * @param suffix The suffix to append to the end of the string.
425     * @param ignoreCase Indicates whether the compare should ignore case.
426     * @param suffixes Additional suffixes that are valid terminators (optional).
427     *
428     * @return A new String if suffix was appended, the same string otherwise.
429     */
430    private static String appendIfMissing(final String str, final CharSequence suffix, final boolean ignoreCase, final CharSequence... suffixes) {
431        if (str == null || isEmpty(suffix) || endsWith(str, suffix, ignoreCase)) {
432            return str;
433        }
434        if (ArrayUtils.isNotEmpty(suffixes)) {
435            for (final CharSequence s : suffixes) {
436                if (endsWith(str, s, ignoreCase)) {
437                    return str;
438                }
439            }
440        }
441        return str + suffix.toString();
442    }
443
444    /**
445     * Appends the suffix to the end of the string if the string does not
446     * already end with any of the suffixes.
447     *
448     * <pre>
449     * StringUtils.appendIfMissing(null, null) = null
450     * StringUtils.appendIfMissing("abc", null) = "abc"
451     * StringUtils.appendIfMissing("", "xyz") = "xyz"
452     * StringUtils.appendIfMissing("abc", "xyz") = "abcxyz"
453     * StringUtils.appendIfMissing("abcxyz", "xyz") = "abcxyz"
454     * StringUtils.appendIfMissing("abcXYZ", "xyz") = "abcXYZxyz"
455     * </pre>
456     * <p>With additional suffixes,</p>
457     * <pre>
458     * StringUtils.appendIfMissing(null, null, null) = null
459     * StringUtils.appendIfMissing("abc", null, null) = "abc"
460     * StringUtils.appendIfMissing("", "xyz", null) = "xyz"
461     * StringUtils.appendIfMissing("abc", "xyz", new CharSequence[]{null}) = "abcxyz"
462     * StringUtils.appendIfMissing("abc", "xyz", "") = "abc"
463     * StringUtils.appendIfMissing("abc", "xyz", "mno") = "abcxyz"
464     * StringUtils.appendIfMissing("abcxyz", "xyz", "mno") = "abcxyz"
465     * StringUtils.appendIfMissing("abcmno", "xyz", "mno") = "abcmno"
466     * StringUtils.appendIfMissing("abcXYZ", "xyz", "mno") = "abcXYZxyz"
467     * StringUtils.appendIfMissing("abcMNO", "xyz", "mno") = "abcMNOxyz"
468     * </pre>
469     *
470     * @param str The string.
471     * @param suffix The suffix to append to the end of the string.
472     * @param suffixes Additional suffixes that are valid terminators.
473     *
474     * @return A new String if suffix was appended, the same string otherwise.
475     *
476     * @since 3.2
477     */
478    public static String appendIfMissing(final String str, final CharSequence suffix, final CharSequence... suffixes) {
479        return appendIfMissing(str, suffix, false, suffixes);
480    }
481
482    /**
483     * Appends the suffix to the end of the string if the string does not
484     * already end, case-insensitive, with any of the suffixes.
485     *
486     * <pre>
487     * StringUtils.appendIfMissingIgnoreCase(null, null) = null
488     * StringUtils.appendIfMissingIgnoreCase("abc", null) = "abc"
489     * StringUtils.appendIfMissingIgnoreCase("", "xyz") = "xyz"
490     * StringUtils.appendIfMissingIgnoreCase("abc", "xyz") = "abcxyz"
491     * StringUtils.appendIfMissingIgnoreCase("abcxyz", "xyz") = "abcxyz"
492     * StringUtils.appendIfMissingIgnoreCase("abcXYZ", "xyz") = "abcXYZ"
493     * </pre>
494     * <p>With additional suffixes,</p>
495     * <pre>
496     * StringUtils.appendIfMissingIgnoreCase(null, null, null) = null
497     * StringUtils.appendIfMissingIgnoreCase("abc", null, null) = "abc"
498     * StringUtils.appendIfMissingIgnoreCase("", "xyz", null) = "xyz"
499     * StringUtils.appendIfMissingIgnoreCase("abc", "xyz", new CharSequence[]{null}) = "abcxyz"
500     * StringUtils.appendIfMissingIgnoreCase("abc", "xyz", "") = "abc"
501     * StringUtils.appendIfMissingIgnoreCase("abc", "xyz", "mno") = "abcxyz"
502     * StringUtils.appendIfMissingIgnoreCase("abcxyz", "xyz", "mno") = "abcxyz"
503     * StringUtils.appendIfMissingIgnoreCase("abcmno", "xyz", "mno") = "abcmno"
504     * StringUtils.appendIfMissingIgnoreCase("abcXYZ", "xyz", "mno") = "abcXYZ"
505     * StringUtils.appendIfMissingIgnoreCase("abcMNO", "xyz", "mno") = "abcMNO"
506     * </pre>
507     *
508     * @param str The string.
509     * @param suffix The suffix to append to the end of the string.
510     * @param suffixes Additional suffixes that are valid terminators.
511     *
512     * @return A new String if suffix was appended, the same string otherwise.
513     *
514     * @since 3.2
515     */
516    public static String appendIfMissingIgnoreCase(final String str, final CharSequence suffix, final CharSequence... suffixes) {
517        return appendIfMissing(str, suffix, true, suffixes);
518    }
519
520    /**
521     * Capitalizes a String changing the first character to title case as
522     * per {@link Character#toTitleCase(int)}. No other characters are changed.
523     *
524     * <p>For a word based algorithm, see {@link org.apache.commons.text.WordUtils#capitalize(String)}.
525     * A {@code null} input String returns {@code null}.</p>
526     *
527     * <pre>
528     * StringUtils.capitalize(null)  = null
529     * StringUtils.capitalize("")    = ""
530     * StringUtils.capitalize("cat") = "Cat"
531     * StringUtils.capitalize("cAt") = "CAt"
532     * StringUtils.capitalize("'cat'") = "'cat'"
533     * </pre>
534     *
535     * @param str the String to capitalize, may be null
536     * @return the capitalized String, {@code null} if null String input
537     * @see org.apache.commons.text.WordUtils#capitalize(String)
538     * @see #uncapitalize(String)
539     * @since 2.0
540     */
541    public static String capitalize(final String str) {
542        final int strLen = length(str);
543        if (strLen == 0) {
544            return str;
545        }
546
547        final int firstCodepoint = str.codePointAt(0);
548        final int newCodePoint = Character.toTitleCase(firstCodepoint);
549        if (firstCodepoint == newCodePoint) {
550            // already capitalized
551            return str;
552        }
553
554        final int[] newCodePoints = new int[strLen]; // cannot be longer than the char array
555        int outOffset = 0;
556        newCodePoints[outOffset++] = newCodePoint; // copy the first code point
557        for (int inOffset = Character.charCount(firstCodepoint); inOffset < strLen; ) {
558            final int codePoint = str.codePointAt(inOffset);
559            newCodePoints[outOffset++] = codePoint; // copy the remaining ones
560            inOffset += Character.charCount(codePoint);
561         }
562        return new String(newCodePoints, 0, outOffset);
563    }
564
565    /**
566     * Centers a String in a larger String of size {@code size}
567     * using the space character (' ').
568     *
569     * <p>If the size is less than the String length, the original String is returned.
570     * A {@code null} String returns {@code null}.
571     * A negative size is treated as zero.</p>
572     *
573     * <p>Equivalent to {@code center(str, size, " ")}.</p>
574     *
575     * <pre>
576     * StringUtils.center(null, *)   = null
577     * StringUtils.center("", 4)     = "    "
578     * StringUtils.center("ab", -1)  = "ab"
579     * StringUtils.center("ab", 4)   = " ab "
580     * StringUtils.center("abcd", 2) = "abcd"
581     * StringUtils.center("a", 4)    = " a  "
582     * </pre>
583     *
584     * @param str  the String to center, may be null
585     * @param size  the int size of new String, negative treated as zero
586     * @return centered String, {@code null} if null String input
587     */
588    public static String center(final String str, final int size) {
589        return center(str, size, ' ');
590    }
591
592    /**
593     * Centers a String in a larger String of size {@code size}.
594     * Uses a supplied character as the value to pad the String with.
595     *
596     * <p>If the size is less than the String length, the String is returned.
597     * A {@code null} String returns {@code null}.
598     * A negative size is treated as zero.</p>
599     *
600     * <pre>
601     * StringUtils.center(null, *, *)     = null
602     * StringUtils.center("", 4, ' ')     = "    "
603     * StringUtils.center("ab", -1, ' ')  = "ab"
604     * StringUtils.center("ab", 4, ' ')   = " ab "
605     * StringUtils.center("abcd", 2, ' ') = "abcd"
606     * StringUtils.center("a", 4, ' ')    = " a  "
607     * StringUtils.center("a", 4, 'y')    = "yayy"
608     * </pre>
609     *
610     * @param str  the String to center, may be null
611     * @param size  the int size of new String, negative treated as zero
612     * @param padChar  the character to pad the new String with
613     * @return centered String, {@code null} if null String input
614     * @since 2.0
615     */
616    public static String center(String str, final int size, final char padChar) {
617        if (str == null || size <= 0) {
618            return str;
619        }
620        final int strLen = str.length();
621        final int pads = size - strLen;
622        if (pads <= 0) {
623            return str;
624        }
625        str = leftPad(str, strLen + pads / 2, padChar);
626        str = rightPad(str, size, padChar);
627        return str;
628    }
629
630    /**
631     * Centers a String in a larger String of size {@code size}.
632     * Uses a supplied String as the value to pad the String with.
633     *
634     * <p>If the size is less than the String length, the String is returned.
635     * A {@code null} String returns {@code null}.
636     * A negative size is treated as zero.</p>
637     *
638     * <pre>
639     * StringUtils.center(null, *, *)     = null
640     * StringUtils.center("", 4, " ")     = "    "
641     * StringUtils.center("ab", -1, " ")  = "ab"
642     * StringUtils.center("ab", 4, " ")   = " ab "
643     * StringUtils.center("abcd", 2, " ") = "abcd"
644     * StringUtils.center("a", 4, " ")    = " a  "
645     * StringUtils.center("a", 4, "yz")   = "yayz"
646     * StringUtils.center("abc", 7, null) = "  abc  "
647     * StringUtils.center("abc", 7, "")   = "  abc  "
648     * </pre>
649     *
650     * @param str  the String to center, may be null
651     * @param size  the int size of new String, negative treated as zero
652     * @param padStr  the String to pad the new String with, must not be null or empty
653     * @return centered String, {@code null} if null String input
654     * @throws IllegalArgumentException if padStr is {@code null} or empty
655     */
656    public static String center(String str, final int size, String padStr) {
657        if (str == null || size <= 0) {
658            return str;
659        }
660        if (isEmpty(padStr)) {
661            padStr = SPACE;
662        }
663        final int strLen = str.length();
664        final int pads = size - strLen;
665        if (pads <= 0) {
666            return str;
667        }
668        str = leftPad(str, strLen + pads / 2, padStr);
669        str = rightPad(str, size, padStr);
670        return str;
671    }
672
673    /**
674     * Removes one newline from end of a String if it's there,
675     * otherwise leave it alone.  A newline is &quot;{@code \n}&quot;,
676     * &quot;{@code \r}&quot;, or &quot;{@code \r\n}&quot;.
677     *
678     * <p>NOTE: This method changed in 2.0.
679     * It now more closely matches Perl chomp.</p>
680     *
681     * <pre>
682     * StringUtils.chomp(null)          = null
683     * StringUtils.chomp("")            = ""
684     * StringUtils.chomp("abc \r")      = "abc "
685     * StringUtils.chomp("abc\n")       = "abc"
686     * StringUtils.chomp("abc\r\n")     = "abc"
687     * StringUtils.chomp("abc\r\n\r\n") = "abc\r\n"
688     * StringUtils.chomp("abc\n\r")     = "abc\n"
689     * StringUtils.chomp("abc\n\rabc")  = "abc\n\rabc"
690     * StringUtils.chomp("\r")          = ""
691     * StringUtils.chomp("\n")          = ""
692     * StringUtils.chomp("\r\n")        = ""
693     * </pre>
694     *
695     * @param str  the String to chomp a newline from, may be null
696     * @return String without newline, {@code null} if null String input
697     */
698    public static String chomp(final String str) {
699        if (isEmpty(str)) {
700            return str;
701        }
702
703        if (str.length() == 1) {
704            final char ch = str.charAt(0);
705            if (ch == CharUtils.CR || ch == CharUtils.LF) {
706                return EMPTY;
707            }
708            return str;
709        }
710
711        int lastIdx = str.length() - 1;
712        final char last = str.charAt(lastIdx);
713
714        if (last == CharUtils.LF) {
715            if (str.charAt(lastIdx - 1) == CharUtils.CR) {
716                lastIdx--;
717            }
718        } else if (last != CharUtils.CR) {
719            lastIdx++;
720        }
721        return str.substring(0, lastIdx);
722    }
723
724    /**
725     * Removes {@code separator} from the end of
726     * {@code str} if it's there, otherwise leave it alone.
727     *
728     * <p>NOTE: This method changed in version 2.0.
729     * It now more closely matches Perl chomp.
730     * For the previous behavior, use {@link #substringBeforeLast(String, String)}.
731     * This method uses {@link String#endsWith(String)}.</p>
732     *
733     * <pre>
734     * StringUtils.chomp(null, *)         = null
735     * StringUtils.chomp("", *)           = ""
736     * StringUtils.chomp("foobar", "bar") = "foo"
737     * StringUtils.chomp("foobar", "baz") = "foobar"
738     * StringUtils.chomp("foo", "foo")    = ""
739     * StringUtils.chomp("foo ", "foo")   = "foo "
740     * StringUtils.chomp(" foo", "foo")   = " "
741     * StringUtils.chomp("foo", "foooo")  = "foo"
742     * StringUtils.chomp("foo", "")       = "foo"
743     * StringUtils.chomp("foo", null)     = "foo"
744     * </pre>
745     *
746     * @param str  the String to chomp from, may be null
747     * @param separator  separator String, may be null
748     * @return String without trailing separator, {@code null} if null String input
749     * @deprecated This feature will be removed in Lang 4, use {@link StringUtils#removeEnd(String, String)} instead
750     */
751    @Deprecated
752    public static String chomp(final String str, final String separator) {
753        return removeEnd(str, separator);
754    }
755
756    /**
757     * Remove the last character from a String.
758     *
759     * <p>If the String ends in {@code \r\n}, then remove both
760     * of them.</p>
761     *
762     * <pre>
763     * StringUtils.chop(null)          = null
764     * StringUtils.chop("")            = ""
765     * StringUtils.chop("abc \r")      = "abc "
766     * StringUtils.chop("abc\n")       = "abc"
767     * StringUtils.chop("abc\r\n")     = "abc"
768     * StringUtils.chop("abc")         = "ab"
769     * StringUtils.chop("abc\nabc")    = "abc\nab"
770     * StringUtils.chop("a")           = ""
771     * StringUtils.chop("\r")          = ""
772     * StringUtils.chop("\n")          = ""
773     * StringUtils.chop("\r\n")        = ""
774     * </pre>
775     *
776     * @param str  the String to chop last character from, may be null
777     * @return String without last character, {@code null} if null String input
778     */
779    public static String chop(final String str) {
780        if (str == null) {
781            return null;
782        }
783        final int strLen = str.length();
784        if (strLen < 2) {
785            return EMPTY;
786        }
787        final int lastIdx = strLen - 1;
788        final String ret = str.substring(0, lastIdx);
789        final char last = str.charAt(lastIdx);
790        if (last == CharUtils.LF && ret.charAt(lastIdx - 1) == CharUtils.CR) {
791            return ret.substring(0, lastIdx - 1);
792        }
793        return ret;
794    }
795
796    /**
797     * Compare two Strings lexicographically, as per {@link String#compareTo(String)}, returning :
798     * <ul>
799     *  <li>{@code int = 0}, if {@code str1} is equal to {@code str2} (or both {@code null})</li>
800     *  <li>{@code int < 0}, if {@code str1} is less than {@code str2}</li>
801     *  <li>{@code int > 0}, if {@code str1} is greater than {@code str2}</li>
802     * </ul>
803     *
804     * <p>This is a {@code null} safe version of :</p>
805     * <blockquote><pre>str1.compareTo(str2)</pre></blockquote>
806     *
807     * <p>{@code null} value is considered less than non-{@code null} value.
808     * Two {@code null} references are considered equal.</p>
809     *
810     * <pre>
811     * StringUtils.compare(null, null)   = 0
812     * StringUtils.compare(null , "a")   &lt; 0
813     * StringUtils.compare("a", null)    &gt; 0
814     * StringUtils.compare("abc", "abc") = 0
815     * StringUtils.compare("a", "b")     &lt; 0
816     * StringUtils.compare("b", "a")     &gt; 0
817     * StringUtils.compare("a", "B")     &gt; 0
818     * StringUtils.compare("ab", "abc")  &lt; 0
819     * </pre>
820     *
821     * @see #compare(String, String, boolean)
822     * @see String#compareTo(String)
823     * @param str1  the String to compare from
824     * @param str2  the String to compare to
825     * @return &lt; 0, 0, &gt; 0, if {@code str1} is respectively less, equal or greater than {@code str2}
826     * @since 3.5
827     */
828    public static int compare(final String str1, final String str2) {
829        return compare(str1, str2, true);
830    }
831
832    /**
833     * Compare two Strings lexicographically, as per {@link String#compareTo(String)}, returning :
834     * <ul>
835     *  <li>{@code int = 0}, if {@code str1} is equal to {@code str2} (or both {@code null})</li>
836     *  <li>{@code int < 0}, if {@code str1} is less than {@code str2}</li>
837     *  <li>{@code int > 0}, if {@code str1} is greater than {@code str2}</li>
838     * </ul>
839     *
840     * <p>This is a {@code null} safe version of :</p>
841     * <blockquote><pre>str1.compareTo(str2)</pre></blockquote>
842     *
843     * <p>{@code null} inputs are handled according to the {@code nullIsLess} parameter.
844     * Two {@code null} references are considered equal.</p>
845     *
846     * <pre>
847     * StringUtils.compare(null, null, *)     = 0
848     * StringUtils.compare(null , "a", true)  &lt; 0
849     * StringUtils.compare(null , "a", false) &gt; 0
850     * StringUtils.compare("a", null, true)   &gt; 0
851     * StringUtils.compare("a", null, false)  &lt; 0
852     * StringUtils.compare("abc", "abc", *)   = 0
853     * StringUtils.compare("a", "b", *)       &lt; 0
854     * StringUtils.compare("b", "a", *)       &gt; 0
855     * StringUtils.compare("a", "B", *)       &gt; 0
856     * StringUtils.compare("ab", "abc", *)    &lt; 0
857     * </pre>
858     *
859     * @see String#compareTo(String)
860     * @param str1  the String to compare from
861     * @param str2  the String to compare to
862     * @param nullIsLess  whether consider {@code null} value less than non-{@code null} value
863     * @return &lt; 0, 0, &gt; 0, if {@code str1} is respectively less, equal ou greater than {@code str2}
864     * @since 3.5
865     */
866    public static int compare(final String str1, final String str2, final boolean nullIsLess) {
867        if (str1 == str2) { // NOSONARLINT this intentionally uses == to allow for both null
868            return 0;
869        }
870        if (str1 == null) {
871            return nullIsLess ? -1 : 1;
872        }
873        if (str2 == null) {
874            return nullIsLess ? 1 : - 1;
875        }
876        return str1.compareTo(str2);
877    }
878
879    /**
880     * Compare two Strings lexicographically, ignoring case differences,
881     * as per {@link String#compareToIgnoreCase(String)}, returning :
882     * <ul>
883     *  <li>{@code int = 0}, if {@code str1} is equal to {@code str2} (or both {@code null})</li>
884     *  <li>{@code int < 0}, if {@code str1} is less than {@code str2}</li>
885     *  <li>{@code int > 0}, if {@code str1} is greater than {@code str2}</li>
886     * </ul>
887     *
888     * <p>This is a {@code null} safe version of :</p>
889     * <blockquote><pre>str1.compareToIgnoreCase(str2)</pre></blockquote>
890     *
891     * <p>{@code null} value is considered less than non-{@code null} value.
892     * Two {@code null} references are considered equal.
893     * Comparison is case insensitive.</p>
894     *
895     * <pre>
896     * StringUtils.compareIgnoreCase(null, null)   = 0
897     * StringUtils.compareIgnoreCase(null , "a")   &lt; 0
898     * StringUtils.compareIgnoreCase("a", null)    &gt; 0
899     * StringUtils.compareIgnoreCase("abc", "abc") = 0
900     * StringUtils.compareIgnoreCase("abc", "ABC") = 0
901     * StringUtils.compareIgnoreCase("a", "b")     &lt; 0
902     * StringUtils.compareIgnoreCase("b", "a")     &gt; 0
903     * StringUtils.compareIgnoreCase("a", "B")     &lt; 0
904     * StringUtils.compareIgnoreCase("A", "b")     &lt; 0
905     * StringUtils.compareIgnoreCase("ab", "ABC")  &lt; 0
906     * </pre>
907     *
908     * @see #compareIgnoreCase(String, String, boolean)
909     * @see String#compareToIgnoreCase(String)
910     * @param str1  the String to compare from
911     * @param str2  the String to compare to
912     * @return &lt; 0, 0, &gt; 0, if {@code str1} is respectively less, equal ou greater than {@code str2},
913     *          ignoring case differences.
914     * @since 3.5
915     */
916    public static int compareIgnoreCase(final String str1, final String str2) {
917        return compareIgnoreCase(str1, str2, true);
918    }
919
920    /**
921     * Compare two Strings lexicographically, ignoring case differences,
922     * as per {@link String#compareToIgnoreCase(String)}, returning :
923     * <ul>
924     *  <li>{@code int = 0}, if {@code str1} is equal to {@code str2} (or both {@code null})</li>
925     *  <li>{@code int < 0}, if {@code str1} is less than {@code str2}</li>
926     *  <li>{@code int > 0}, if {@code str1} is greater than {@code str2}</li>
927     * </ul>
928     *
929     * <p>This is a {@code null} safe version of :</p>
930     * <blockquote><pre>str1.compareToIgnoreCase(str2)</pre></blockquote>
931     *
932     * <p>{@code null} inputs are handled according to the {@code nullIsLess} parameter.
933     * Two {@code null} references are considered equal.
934     * Comparison is case insensitive.</p>
935     *
936     * <pre>
937     * StringUtils.compareIgnoreCase(null, null, *)     = 0
938     * StringUtils.compareIgnoreCase(null , "a", true)  &lt; 0
939     * StringUtils.compareIgnoreCase(null , "a", false) &gt; 0
940     * StringUtils.compareIgnoreCase("a", null, true)   &gt; 0
941     * StringUtils.compareIgnoreCase("a", null, false)  &lt; 0
942     * StringUtils.compareIgnoreCase("abc", "abc", *)   = 0
943     * StringUtils.compareIgnoreCase("abc", "ABC", *)   = 0
944     * StringUtils.compareIgnoreCase("a", "b", *)       &lt; 0
945     * StringUtils.compareIgnoreCase("b", "a", *)       &gt; 0
946     * StringUtils.compareIgnoreCase("a", "B", *)       &lt; 0
947     * StringUtils.compareIgnoreCase("A", "b", *)       &lt; 0
948     * StringUtils.compareIgnoreCase("ab", "abc", *)    &lt; 0
949     * </pre>
950     *
951     * @see String#compareToIgnoreCase(String)
952     * @param str1  the String to compare from
953     * @param str2  the String to compare to
954     * @param nullIsLess  whether consider {@code null} value less than non-{@code null} value
955     * @return &lt; 0, 0, &gt; 0, if {@code str1} is respectively less, equal ou greater than {@code str2},
956     *          ignoring case differences.
957     * @since 3.5
958     */
959    public static int compareIgnoreCase(final String str1, final String str2, final boolean nullIsLess) {
960        if (str1 == str2) { // NOSONARLINT this intentionally uses == to allow for both null
961            return 0;
962        }
963        if (str1 == null) {
964            return nullIsLess ? -1 : 1;
965        }
966        if (str2 == null) {
967            return nullIsLess ? 1 : - 1;
968        }
969        return str1.compareToIgnoreCase(str2);
970    }
971
972    /**
973     * Checks if CharSequence contains a search CharSequence, handling {@code null}.
974     * This method uses {@link String#indexOf(String)} if possible.
975     *
976     * <p>A {@code null} CharSequence will return {@code false}.</p>
977     *
978     * <pre>
979     * StringUtils.contains(null, *)     = false
980     * StringUtils.contains(*, null)     = false
981     * StringUtils.contains("", "")      = true
982     * StringUtils.contains("abc", "")   = true
983     * StringUtils.contains("abc", "a")  = true
984     * StringUtils.contains("abc", "z")  = false
985     * </pre>
986     *
987     * @param seq  the CharSequence to check, may be null
988     * @param searchSeq  the CharSequence to find, may be null
989     * @return true if the CharSequence contains the search CharSequence,
990     *  false if not or {@code null} string input
991     * @since 2.0
992     * @since 3.0 Changed signature from contains(String, String) to contains(CharSequence, CharSequence)
993     */
994    public static boolean contains(final CharSequence seq, final CharSequence searchSeq) {
995        if (seq == null || searchSeq == null) {
996            return false;
997        }
998        return CharSequenceUtils.indexOf(seq, searchSeq, 0) >= 0;
999    }
1000
1001    /**
1002     * Checks if CharSequence contains a search character, handling {@code null}.
1003     * This method uses {@link String#indexOf(int)} if possible.
1004     *
1005     * <p>A {@code null} or empty ("") CharSequence will return {@code false}.</p>
1006     *
1007     * <pre>
1008     * StringUtils.contains(null, *)    = false
1009     * StringUtils.contains("", *)      = false
1010     * StringUtils.contains("abc", 'a') = true
1011     * StringUtils.contains("abc", 'z') = false
1012     * </pre>
1013     *
1014     * @param seq  the CharSequence to check, may be null
1015     * @param searchChar  the character to find
1016     * @return true if the CharSequence contains the search character,
1017     *  false if not or {@code null} string input
1018     * @since 2.0
1019     * @since 3.0 Changed signature from contains(String, int) to contains(CharSequence, int)
1020     */
1021    public static boolean contains(final CharSequence seq, final int searchChar) {
1022        if (isEmpty(seq)) {
1023            return false;
1024        }
1025        return CharSequenceUtils.indexOf(seq, searchChar, 0) >= 0;
1026    }
1027
1028    /**
1029     * Checks if the CharSequence contains any character in the given
1030     * set of characters.
1031     *
1032     * <p>A {@code null} CharSequence will return {@code false}.
1033     * A {@code null} or zero length search array will return {@code false}.</p>
1034     *
1035     * <pre>
1036     * StringUtils.containsAny(null, *)                  = false
1037     * StringUtils.containsAny("", *)                    = false
1038     * StringUtils.containsAny(*, null)                  = false
1039     * StringUtils.containsAny(*, [])                    = false
1040     * StringUtils.containsAny("zzabyycdxx", ['z', 'a']) = true
1041     * StringUtils.containsAny("zzabyycdxx", ['b', 'y']) = true
1042     * StringUtils.containsAny("zzabyycdxx", ['z', 'y']) = true
1043     * StringUtils.containsAny("aba", ['z'])             = false
1044     * </pre>
1045     *
1046     * @param cs  the CharSequence to check, may be null
1047     * @param searchChars  the chars to search for, may be null
1048     * @return the {@code true} if any of the chars are found,
1049     * {@code false} if no match or null input
1050     * @since 2.4
1051     * @since 3.0 Changed signature from containsAny(String, char[]) to containsAny(CharSequence, char...)
1052     */
1053    public static boolean containsAny(final CharSequence cs, final char... searchChars) {
1054        if (isEmpty(cs) || ArrayUtils.isEmpty(searchChars)) {
1055            return false;
1056        }
1057        final int csLength = cs.length();
1058        final int searchLength = searchChars.length;
1059        final int csLast = csLength - 1;
1060        final int searchLast = searchLength - 1;
1061        for (int i = 0; i < csLength; i++) {
1062            final char ch = cs.charAt(i);
1063            for (int j = 0; j < searchLength; j++) {
1064                if (searchChars[j] == ch) {
1065                    if (!Character.isHighSurrogate(ch)) {
1066                        // ch is in the Basic Multilingual Plane
1067                        return true;
1068                    }
1069                    if (j == searchLast) {
1070                        // missing low surrogate, fine, like String.indexOf(String)
1071                        return true;
1072                    }
1073                    if (i < csLast && searchChars[j + 1] == cs.charAt(i + 1)) {
1074                        return true;
1075                    }
1076                }
1077            }
1078        }
1079        return false;
1080    }
1081
1082    /**
1083     * Checks if the CharSequence contains any character in the given set of characters.
1084     *
1085     * <p>
1086     * A {@code null} CharSequence will return {@code false}. A {@code null} search CharSequence will return
1087     * {@code false}.
1088     * </p>
1089     *
1090     * <pre>
1091     * StringUtils.containsAny(null, *)               = false
1092     * StringUtils.containsAny("", *)                 = false
1093     * StringUtils.containsAny(*, null)               = false
1094     * StringUtils.containsAny(*, "")                 = false
1095     * StringUtils.containsAny("zzabyycdxx", "za")    = true
1096     * StringUtils.containsAny("zzabyycdxx", "by")    = true
1097     * StringUtils.containsAny("zzabyycdxx", "zy")    = true
1098     * StringUtils.containsAny("zzabyycdxx", "\tx")   = true
1099     * StringUtils.containsAny("zzabyycdxx", "$.#yF") = true
1100     * StringUtils.containsAny("aba", "z")            = false
1101     * </pre>
1102     *
1103     * @param cs
1104     *            the CharSequence to check, may be null
1105     * @param searchChars
1106     *            the chars to search for, may be null
1107     * @return the {@code true} if any of the chars are found, {@code false} if no match or null input
1108     * @since 2.4
1109     * @since 3.0 Changed signature from containsAny(String, String) to containsAny(CharSequence, CharSequence)
1110     */
1111    public static boolean containsAny(final CharSequence cs, final CharSequence searchChars) {
1112        if (searchChars == null) {
1113            return false;
1114        }
1115        return containsAny(cs, CharSequenceUtils.toCharArray(searchChars));
1116    }
1117
1118    /**
1119     * Checks if the CharSequence contains any of the CharSequences in the given array.
1120     *
1121     * <p>
1122     * A {@code null} {@code cs} CharSequence will return {@code false}. A {@code null} or zero length search array will
1123     * return {@code false}.
1124     * </p>
1125     *
1126     * <pre>
1127     * StringUtils.containsAny(null, *)            = false
1128     * StringUtils.containsAny("", *)              = false
1129     * StringUtils.containsAny(*, null)            = false
1130     * StringUtils.containsAny(*, [])              = false
1131     * StringUtils.containsAny("abcd", "ab", null) = true
1132     * StringUtils.containsAny("abcd", "ab", "cd") = true
1133     * StringUtils.containsAny("abc", "d", "abc")  = true
1134     * </pre>
1135     *
1136     * @param cs The CharSequence to check, may be null
1137     * @param searchCharSequences The array of CharSequences to search for, may be null. Individual CharSequences may be
1138     *        null as well.
1139     * @return {@code true} if any of the search CharSequences are found, {@code false} otherwise
1140     * @since 3.4
1141     */
1142    public static boolean containsAny(final CharSequence cs, final CharSequence... searchCharSequences) {
1143        return containsAny(StringUtils::contains, cs, searchCharSequences);
1144    }
1145
1146    /**
1147     * Checks if the CharSequence contains any of the CharSequences in the given array.
1148     *
1149     * <p>
1150     * A {@code null} {@code cs} CharSequence will return {@code false}. A {@code null} or zero length search array will
1151     * return {@code false}.
1152     * </p>
1153     *
1154     * @param cs The CharSequence to check, may be null
1155     * @param searchCharSequences The array of CharSequences to search for, may be null. Individual CharSequences may be
1156     *        null as well.
1157     * @return {@code true} if any of the search CharSequences are found, {@code false} otherwise
1158     * @since 3.12.0
1159     */
1160    private static boolean containsAny(final ToBooleanBiFunction<CharSequence, CharSequence> test,
1161        final CharSequence cs, final CharSequence... searchCharSequences) {
1162        if (isEmpty(cs) || ArrayUtils.isEmpty(searchCharSequences)) {
1163            return false;
1164        }
1165        for (final CharSequence searchCharSequence : searchCharSequences) {
1166            if (test.applyAsBoolean(cs, searchCharSequence)) {
1167                return true;
1168            }
1169        }
1170        return false;
1171    }
1172
1173    /**
1174     * Checks if the CharSequence contains any of the CharSequences in the given array, ignoring case.
1175     *
1176     * <p>
1177     * A {@code null} {@code cs} CharSequence will return {@code false}. A {@code null} or zero length search array will
1178     * return {@code false}.
1179     * </p>
1180     *
1181     * <pre>
1182     * StringUtils.containsAny(null, *)            = false
1183     * StringUtils.containsAny("", *)              = false
1184     * StringUtils.containsAny(*, null)            = false
1185     * StringUtils.containsAny(*, [])              = false
1186     * StringUtils.containsAny("abcd", "ab", null) = true
1187     * StringUtils.containsAny("abcd", "ab", "cd") = true
1188     * StringUtils.containsAny("abc", "d", "abc")  = true
1189     * StringUtils.containsAny("abc", "D", "ABC")  = true
1190     * StringUtils.containsAny("ABC", "d", "abc")  = true
1191     * </pre>
1192     *
1193     * @param cs The CharSequence to check, may be null
1194     * @param searchCharSequences The array of CharSequences to search for, may be null. Individual CharSequences may be
1195     *        null as well.
1196     * @return {@code true} if any of the search CharSequences are found, {@code false} otherwise
1197     * @since 3.12.0
1198     */
1199    public static boolean containsAnyIgnoreCase(final CharSequence cs, final CharSequence... searchCharSequences) {
1200        return containsAny(StringUtils::containsIgnoreCase, cs, searchCharSequences);
1201    }
1202
1203    /**
1204     * Checks if CharSequence contains a search CharSequence irrespective of case,
1205     * handling {@code null}. Case-insensitivity is defined as by
1206     * {@link String#equalsIgnoreCase(String)}.
1207     *
1208     * <p>A {@code null} CharSequence will return {@code false}.
1209     *
1210     * <pre>
1211     * StringUtils.containsIgnoreCase(null, *) = false
1212     * StringUtils.containsIgnoreCase(*, null) = false
1213     * StringUtils.containsIgnoreCase("", "") = true
1214     * StringUtils.containsIgnoreCase("abc", "") = true
1215     * StringUtils.containsIgnoreCase("abc", "a") = true
1216     * StringUtils.containsIgnoreCase("abc", "z") = false
1217     * StringUtils.containsIgnoreCase("abc", "A") = true
1218     * StringUtils.containsIgnoreCase("abc", "Z") = false
1219     * </pre>
1220     *
1221     * @param str  the CharSequence to check, may be null
1222     * @param searchStr  the CharSequence to find, may be null
1223     * @return true if the CharSequence contains the search CharSequence irrespective of
1224     * case or false if not or {@code null} string input
1225     * @since 3.0 Changed signature from containsIgnoreCase(String, String) to containsIgnoreCase(CharSequence, CharSequence)
1226     */
1227    public static boolean containsIgnoreCase(final CharSequence str, final CharSequence searchStr) {
1228        if (str == null || searchStr == null) {
1229            return false;
1230        }
1231        final int len = searchStr.length();
1232        final int max = str.length() - len;
1233        for (int i = 0; i <= max; i++) {
1234            if (CharSequenceUtils.regionMatches(str, true, i, searchStr, 0, len)) {
1235                return true;
1236            }
1237        }
1238        return false;
1239    }
1240
1241    /**
1242     * Checks that the CharSequence does not contain certain characters.
1243     *
1244     * <p>A {@code null} CharSequence will return {@code true}.
1245     * A {@code null} invalid character array will return {@code true}.
1246     * An empty CharSequence (length()=0) always returns true.</p>
1247     *
1248     * <pre>
1249     * StringUtils.containsNone(null, *)       = true
1250     * StringUtils.containsNone(*, null)       = true
1251     * StringUtils.containsNone("", *)         = true
1252     * StringUtils.containsNone("ab", '')      = true
1253     * StringUtils.containsNone("abab", 'xyz') = true
1254     * StringUtils.containsNone("ab1", 'xyz')  = true
1255     * StringUtils.containsNone("abz", 'xyz')  = false
1256     * </pre>
1257     *
1258     * @param cs  the CharSequence to check, may be null
1259     * @param searchChars  an array of invalid chars, may be null
1260     * @return true if it contains none of the invalid chars, or is null
1261     * @since 2.0
1262     * @since 3.0 Changed signature from containsNone(String, char[]) to containsNone(CharSequence, char...)
1263     */
1264    public static boolean containsNone(final CharSequence cs, final char... searchChars) {
1265        if (cs == null || searchChars == null) {
1266            return true;
1267        }
1268        final int csLen = cs.length();
1269        final int csLast = csLen - 1;
1270        final int searchLen = searchChars.length;
1271        final int searchLast = searchLen - 1;
1272        for (int i = 0; i < csLen; i++) {
1273            final char ch = cs.charAt(i);
1274            for (int j = 0; j < searchLen; j++) {
1275                if (searchChars[j] == ch) {
1276                    if (!Character.isHighSurrogate(ch)) {
1277                        // ch is in the Basic Multilingual Plane
1278                        return false;
1279                    }
1280                    if (j == searchLast) {
1281                        // missing low surrogate, fine, like String.indexOf(String)
1282                        return false;
1283                    }
1284                    if (i < csLast && searchChars[j + 1] == cs.charAt(i + 1)) {
1285                        return false;
1286                    }
1287                }
1288            }
1289        }
1290        return true;
1291    }
1292
1293    /**
1294     * Checks that the CharSequence does not contain certain characters.
1295     *
1296     * <p>A {@code null} CharSequence will return {@code true}.
1297     * A {@code null} invalid character array will return {@code true}.
1298     * An empty String ("") always returns true.</p>
1299     *
1300     * <pre>
1301     * StringUtils.containsNone(null, *)       = true
1302     * StringUtils.containsNone(*, null)       = true
1303     * StringUtils.containsNone("", *)         = true
1304     * StringUtils.containsNone("ab", "")      = true
1305     * StringUtils.containsNone("abab", "xyz") = true
1306     * StringUtils.containsNone("ab1", "xyz")  = true
1307     * StringUtils.containsNone("abz", "xyz")  = false
1308     * </pre>
1309     *
1310     * @param cs  the CharSequence to check, may be null
1311     * @param invalidChars  a String of invalid chars, may be null
1312     * @return true if it contains none of the invalid chars, or is null
1313     * @since 2.0
1314     * @since 3.0 Changed signature from containsNone(String, String) to containsNone(CharSequence, String)
1315     */
1316    public static boolean containsNone(final CharSequence cs, final String invalidChars) {
1317        if (invalidChars == null) {
1318            return true;
1319        }
1320        return containsNone(cs, invalidChars.toCharArray());
1321    }
1322
1323    /**
1324     * Checks if the CharSequence contains only certain characters.
1325     *
1326     * <p>A {@code null} CharSequence will return {@code false}.
1327     * A {@code null} valid character array will return {@code false}.
1328     * An empty CharSequence (length()=0) always returns {@code true}.</p>
1329     *
1330     * <pre>
1331     * StringUtils.containsOnly(null, *)       = false
1332     * StringUtils.containsOnly(*, null)       = false
1333     * StringUtils.containsOnly("", *)         = true
1334     * StringUtils.containsOnly("ab", '')      = false
1335     * StringUtils.containsOnly("abab", 'abc') = true
1336     * StringUtils.containsOnly("ab1", 'abc')  = false
1337     * StringUtils.containsOnly("abz", 'abc')  = false
1338     * </pre>
1339     *
1340     * @param cs  the String to check, may be null
1341     * @param valid  an array of valid chars, may be null
1342     * @return true if it only contains valid chars and is non-null
1343     * @since 3.0 Changed signature from containsOnly(String, char[]) to containsOnly(CharSequence, char...)
1344     */
1345    public static boolean containsOnly(final CharSequence cs, final char... valid) {
1346        // All these pre-checks are to maintain API with an older version
1347        if (valid == null || cs == null) {
1348            return false;
1349        }
1350        if (cs.length() == 0) {
1351            return true;
1352        }
1353        if (valid.length == 0) {
1354            return false;
1355        }
1356        return indexOfAnyBut(cs, valid) == INDEX_NOT_FOUND;
1357    }
1358
1359    /**
1360     * Checks if the CharSequence contains only certain characters.
1361     *
1362     * <p>A {@code null} CharSequence will return {@code false}.
1363     * A {@code null} valid character String will return {@code false}.
1364     * An empty String (length()=0) always returns {@code true}.</p>
1365     *
1366     * <pre>
1367     * StringUtils.containsOnly(null, *)       = false
1368     * StringUtils.containsOnly(*, null)       = false
1369     * StringUtils.containsOnly("", *)         = true
1370     * StringUtils.containsOnly("ab", "")      = false
1371     * StringUtils.containsOnly("abab", "abc") = true
1372     * StringUtils.containsOnly("ab1", "abc")  = false
1373     * StringUtils.containsOnly("abz", "abc")  = false
1374     * </pre>
1375     *
1376     * @param cs  the CharSequence to check, may be null
1377     * @param validChars  a String of valid chars, may be null
1378     * @return true if it only contains valid chars and is non-null
1379     * @since 2.0
1380     * @since 3.0 Changed signature from containsOnly(String, String) to containsOnly(CharSequence, String)
1381     */
1382    public static boolean containsOnly(final CharSequence cs, final String validChars) {
1383        if (cs == null || validChars == null) {
1384            return false;
1385        }
1386        return containsOnly(cs, validChars.toCharArray());
1387    }
1388
1389    /**
1390     * Check whether the given CharSequence contains any whitespace characters.
1391     *
1392     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
1393     *
1394     * @param seq the CharSequence to check (may be {@code null})
1395     * @return {@code true} if the CharSequence is not empty and
1396     * contains at least 1 (breaking) whitespace character
1397     * @since 3.0
1398     */
1399    // From org.springframework.util.StringUtils, under Apache License 2.0
1400    public static boolean containsWhitespace(final CharSequence seq) {
1401        if (isEmpty(seq)) {
1402            return false;
1403        }
1404        final int strLen = seq.length();
1405        for (int i = 0; i < strLen; i++) {
1406            if (Character.isWhitespace(seq.charAt(i))) {
1407                return true;
1408            }
1409        }
1410        return false;
1411    }
1412
1413    private static void convertRemainingAccentCharacters(final StringBuilder decomposed) {
1414        for (int i = 0; i < decomposed.length(); i++) {
1415            if (decomposed.charAt(i) == '\u0141') {
1416                decomposed.setCharAt(i, 'L');
1417            } else if (decomposed.charAt(i) == '\u0142') {
1418                decomposed.setCharAt(i, 'l');
1419            }
1420        }
1421    }
1422
1423    /**
1424     * Counts how many times the char appears in the given string.
1425     *
1426     * <p>A {@code null} or empty ("") String input returns {@code 0}.</p>
1427     *
1428     * <pre>
1429     * StringUtils.countMatches(null, *)       = 0
1430     * StringUtils.countMatches("", *)         = 0
1431     * StringUtils.countMatches("abba", 0)  = 0
1432     * StringUtils.countMatches("abba", 'a')   = 2
1433     * StringUtils.countMatches("abba", 'b')  = 2
1434     * StringUtils.countMatches("abba", 'x') = 0
1435     * </pre>
1436     *
1437     * @param str  the CharSequence to check, may be null
1438     * @param ch  the char to count
1439     * @return the number of occurrences, 0 if the CharSequence is {@code null}
1440     * @since 3.4
1441     */
1442    public static int countMatches(final CharSequence str, final char ch) {
1443        if (isEmpty(str)) {
1444            return 0;
1445        }
1446        int count = 0;
1447        // We could also call str.toCharArray() for faster lookups but that would generate more garbage.
1448        for (int i = 0; i < str.length(); i++) {
1449            if (ch == str.charAt(i)) {
1450                count++;
1451            }
1452        }
1453        return count;
1454    }
1455
1456    /**
1457     * Counts how many times the substring appears in the larger string.
1458     * Note that the code only counts non-overlapping matches.
1459     *
1460     * <p>A {@code null} or empty ("") String input returns {@code 0}.</p>
1461     *
1462     * <pre>
1463     * StringUtils.countMatches(null, *)       = 0
1464     * StringUtils.countMatches("", *)         = 0
1465     * StringUtils.countMatches("abba", null)  = 0
1466     * StringUtils.countMatches("abba", "")    = 0
1467     * StringUtils.countMatches("abba", "a")   = 2
1468     * StringUtils.countMatches("abba", "ab")  = 1
1469     * StringUtils.countMatches("abba", "xxx") = 0
1470     * StringUtils.countMatches("ababa", "aba") = 1
1471     * </pre>
1472     *
1473     * @param str  the CharSequence to check, may be null
1474     * @param sub  the substring to count, may be null
1475     * @return the number of occurrences, 0 if either CharSequence is {@code null}
1476     * @since 3.0 Changed signature from countMatches(String, String) to countMatches(CharSequence, CharSequence)
1477     */
1478    public static int countMatches(final CharSequence str, final CharSequence sub) {
1479        if (isEmpty(str) || isEmpty(sub)) {
1480            return 0;
1481        }
1482        int count = 0;
1483        int idx = 0;
1484        while ((idx = CharSequenceUtils.indexOf(str, sub, idx)) != INDEX_NOT_FOUND) {
1485            count++;
1486            idx += sub.length();
1487        }
1488        return count;
1489    }
1490
1491    /**
1492     * Returns either the passed in CharSequence, or if the CharSequence is
1493     * whitespace, empty ("") or {@code null}, the value of {@code defaultStr}.
1494     *
1495     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
1496     *
1497     * <pre>
1498     * StringUtils.defaultIfBlank(null, "NULL")  = "NULL"
1499     * StringUtils.defaultIfBlank("", "NULL")    = "NULL"
1500     * StringUtils.defaultIfBlank(" ", "NULL")   = "NULL"
1501     * StringUtils.defaultIfBlank("bat", "NULL") = "bat"
1502     * StringUtils.defaultIfBlank("", null)      = null
1503     * </pre>
1504     * @param <T> the specific kind of CharSequence
1505     * @param str the CharSequence to check, may be null
1506     * @param defaultStr  the default CharSequence to return
1507     *  if the input is whitespace, empty ("") or {@code null}, may be null
1508     * @return the passed in CharSequence, or the default
1509     * @see StringUtils#defaultString(String, String)
1510     */
1511    public static <T extends CharSequence> T defaultIfBlank(final T str, final T defaultStr) {
1512        return isBlank(str) ? defaultStr : str;
1513    }
1514
1515    /**
1516     * Returns either the passed in CharSequence, or if the CharSequence is
1517     * empty or {@code null}, the value of {@code defaultStr}.
1518     *
1519     * <pre>
1520     * StringUtils.defaultIfEmpty(null, "NULL")  = "NULL"
1521     * StringUtils.defaultIfEmpty("", "NULL")    = "NULL"
1522     * StringUtils.defaultIfEmpty(" ", "NULL")   = " "
1523     * StringUtils.defaultIfEmpty("bat", "NULL") = "bat"
1524     * StringUtils.defaultIfEmpty("", null)      = null
1525     * </pre>
1526     * @param <T> the specific kind of CharSequence
1527     * @param str  the CharSequence to check, may be null
1528     * @param defaultStr  the default CharSequence to return
1529     *  if the input is empty ("") or {@code null}, may be null
1530     * @return the passed in CharSequence, or the default
1531     * @see StringUtils#defaultString(String, String)
1532     */
1533    public static <T extends CharSequence> T defaultIfEmpty(final T str, final T defaultStr) {
1534        return isEmpty(str) ? defaultStr : str;
1535    }
1536
1537    /**
1538     * Returns either the passed in String,
1539     * or if the String is {@code null}, an empty String ("").
1540     *
1541     * <pre>
1542     * StringUtils.defaultString(null)  = ""
1543     * StringUtils.defaultString("")    = ""
1544     * StringUtils.defaultString("bat") = "bat"
1545     * </pre>
1546     *
1547     * @see Objects#toString(Object, String)
1548     * @see String#valueOf(Object)
1549     * @param str  the String to check, may be null
1550     * @return the passed in String, or the empty String if it
1551     *  was {@code null}
1552     */
1553    public static String defaultString(final String str) {
1554        return Objects.toString(str, EMPTY);
1555    }
1556
1557    /**
1558     * Returns either the given String, or if the String is
1559     * {@code null}, {@code nullDefault}.
1560     *
1561     * <pre>
1562     * StringUtils.defaultString(null, "NULL")  = "NULL"
1563     * StringUtils.defaultString("", "NULL")    = ""
1564     * StringUtils.defaultString("bat", "NULL") = "bat"
1565     * </pre>
1566     *
1567     * @see Objects#toString(Object, String)
1568     * @see String#valueOf(Object)
1569     * @param str  the String to check, may be null
1570     * @param nullDefault  the default String to return
1571     *  if the input is {@code null}, may be null
1572     * @return the passed in String, or the default if it was {@code null}
1573     * @deprecated Use {@link Objects#toString(Object, String)}
1574     */
1575    @Deprecated
1576    public static String defaultString(final String str, final String nullDefault) {
1577        return Objects.toString(str, nullDefault);
1578    }
1579
1580    /**
1581     * Deletes all whitespaces from a String as defined by
1582     * {@link Character#isWhitespace(char)}.
1583     *
1584     * <pre>
1585     * StringUtils.deleteWhitespace(null)         = null
1586     * StringUtils.deleteWhitespace("")           = ""
1587     * StringUtils.deleteWhitespace("abc")        = "abc"
1588     * StringUtils.deleteWhitespace("   ab  c  ") = "abc"
1589     * </pre>
1590     *
1591     * @param str  the String to delete whitespace from, may be null
1592     * @return the String without whitespaces, {@code null} if null String input
1593     */
1594    public static String deleteWhitespace(final String str) {
1595        if (isEmpty(str)) {
1596            return str;
1597        }
1598        final int sz = str.length();
1599        final char[] chs = new char[sz];
1600        int count = 0;
1601        for (int i = 0; i < sz; i++) {
1602            if (!Character.isWhitespace(str.charAt(i))) {
1603                chs[count++] = str.charAt(i);
1604            }
1605        }
1606        if (count == sz) {
1607            return str;
1608        }
1609        if (count == 0) {
1610            return EMPTY;
1611        }
1612        return new String(chs, 0, count);
1613    }
1614
1615    /**
1616     * Compares two Strings, and returns the portion where they differ.
1617     * More precisely, return the remainder of the second String,
1618     * starting from where it's different from the first. This means that
1619     * the difference between "abc" and "ab" is the empty String and not "c".
1620     *
1621     * <p>For example,
1622     * {@code difference("i am a machine", "i am a robot") -> "robot"}.</p>
1623     *
1624     * <pre>
1625     * StringUtils.difference(null, null) = null
1626     * StringUtils.difference("", "") = ""
1627     * StringUtils.difference("", "abc") = "abc"
1628     * StringUtils.difference("abc", "") = ""
1629     * StringUtils.difference("abc", "abc") = ""
1630     * StringUtils.difference("abc", "ab") = ""
1631     * StringUtils.difference("ab", "abxyz") = "xyz"
1632     * StringUtils.difference("abcde", "abxyz") = "xyz"
1633     * StringUtils.difference("abcde", "xyz") = "xyz"
1634     * </pre>
1635     *
1636     * @param str1  the first String, may be null
1637     * @param str2  the second String, may be null
1638     * @return the portion of str2 where it differs from str1; returns the
1639     * empty String if they are equal
1640     * @see #indexOfDifference(CharSequence,CharSequence)
1641     * @since 2.0
1642     */
1643    public static String difference(final String str1, final String str2) {
1644        if (str1 == null) {
1645            return str2;
1646        }
1647        if (str2 == null) {
1648            return str1;
1649        }
1650        final int at = indexOfDifference(str1, str2);
1651        if (at == INDEX_NOT_FOUND) {
1652            return EMPTY;
1653        }
1654        return str2.substring(at);
1655    }
1656
1657    /**
1658     * Check if a CharSequence ends with a specified suffix.
1659     *
1660     * <p>{@code null}s are handled without exceptions. Two {@code null}
1661     * references are considered to be equal. The comparison is case-sensitive.</p>
1662     *
1663     * <pre>
1664     * StringUtils.endsWith(null, null)      = true
1665     * StringUtils.endsWith(null, "def")     = false
1666     * StringUtils.endsWith("abcdef", null)  = false
1667     * StringUtils.endsWith("abcdef", "def") = true
1668     * StringUtils.endsWith("ABCDEF", "def") = false
1669     * StringUtils.endsWith("ABCDEF", "cde") = false
1670     * StringUtils.endsWith("ABCDEF", "")    = true
1671     * </pre>
1672     *
1673     * @see String#endsWith(String)
1674     * @param str  the CharSequence to check, may be null
1675     * @param suffix the suffix to find, may be null
1676     * @return {@code true} if the CharSequence ends with the suffix, case-sensitive, or
1677     *  both {@code null}
1678     * @since 2.4
1679     * @since 3.0 Changed signature from endsWith(String, String) to endsWith(CharSequence, CharSequence)
1680     */
1681    public static boolean endsWith(final CharSequence str, final CharSequence suffix) {
1682        return endsWith(str, suffix, false);
1683    }
1684
1685    /**
1686     * Check if a CharSequence ends with a specified suffix (optionally case insensitive).
1687     *
1688     * @see String#endsWith(String)
1689     * @param str  the CharSequence to check, may be null
1690     * @param suffix the suffix to find, may be null
1691     * @param ignoreCase indicates whether the compare should ignore case
1692     *  (case-insensitive) or not.
1693     * @return {@code true} if the CharSequence starts with the prefix or
1694     *  both {@code null}
1695     */
1696    private static boolean endsWith(final CharSequence str, final CharSequence suffix, final boolean ignoreCase) {
1697        if (str == null || suffix == null) {
1698            return str == suffix;
1699        }
1700        if (suffix.length() > str.length()) {
1701            return false;
1702        }
1703        final int strOffset = str.length() - suffix.length();
1704        return CharSequenceUtils.regionMatches(str, ignoreCase, strOffset, suffix, 0, suffix.length());
1705    }
1706
1707    /**
1708     * Check if a CharSequence ends with any of the provided case-sensitive suffixes.
1709     *
1710     * <pre>
1711     * StringUtils.endsWithAny(null, null)      = false
1712     * StringUtils.endsWithAny(null, new String[] {"abc"})  = false
1713     * StringUtils.endsWithAny("abcxyz", null)     = false
1714     * StringUtils.endsWithAny("abcxyz", new String[] {""}) = true
1715     * StringUtils.endsWithAny("abcxyz", new String[] {"xyz"}) = true
1716     * StringUtils.endsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true
1717     * StringUtils.endsWithAny("abcXYZ", "def", "XYZ") = true
1718     * StringUtils.endsWithAny("abcXYZ", "def", "xyz") = false
1719     * </pre>
1720     *
1721     * @param sequence  the CharSequence to check, may be null
1722     * @param searchStrings the case-sensitive CharSequences to find, may be empty or contain {@code null}
1723     * @see StringUtils#endsWith(CharSequence, CharSequence)
1724     * @return {@code true} if the input {@code sequence} is {@code null} AND no {@code searchStrings} are provided, or
1725     *   the input {@code sequence} ends in any of the provided case-sensitive {@code searchStrings}.
1726     * @since 3.0
1727     */
1728    public static boolean endsWithAny(final CharSequence sequence, final CharSequence... searchStrings) {
1729        if (isEmpty(sequence) || ArrayUtils.isEmpty(searchStrings)) {
1730            return false;
1731        }
1732        for (final CharSequence searchString : searchStrings) {
1733            if (endsWith(sequence, searchString)) {
1734                return true;
1735            }
1736        }
1737        return false;
1738    }
1739
1740    /**
1741     * Case insensitive check if a CharSequence ends with a specified suffix.
1742     *
1743     * <p>{@code null}s are handled without exceptions. Two {@code null}
1744     * references are considered to be equal. The comparison is case insensitive.</p>
1745     *
1746     * <pre>
1747     * StringUtils.endsWithIgnoreCase(null, null)      = true
1748     * StringUtils.endsWithIgnoreCase(null, "def")     = false
1749     * StringUtils.endsWithIgnoreCase("abcdef", null)  = false
1750     * StringUtils.endsWithIgnoreCase("abcdef", "def") = true
1751     * StringUtils.endsWithIgnoreCase("ABCDEF", "def") = true
1752     * StringUtils.endsWithIgnoreCase("ABCDEF", "cde") = false
1753     * </pre>
1754     *
1755     * @see String#endsWith(String)
1756     * @param str  the CharSequence to check, may be null
1757     * @param suffix the suffix to find, may be null
1758     * @return {@code true} if the CharSequence ends with the suffix, case-insensitive, or
1759     *  both {@code null}
1760     * @since 2.4
1761     * @since 3.0 Changed signature from endsWithIgnoreCase(String, String) to endsWithIgnoreCase(CharSequence, CharSequence)
1762     */
1763    public static boolean endsWithIgnoreCase(final CharSequence str, final CharSequence suffix) {
1764        return endsWith(str, suffix, true);
1765    }
1766
1767    /**
1768     * Compares two CharSequences, returning {@code true} if they represent
1769     * equal sequences of characters.
1770     *
1771     * <p>{@code null}s are handled without exceptions. Two {@code null}
1772     * references are considered to be equal. The comparison is <strong>case-sensitive</strong>.</p>
1773     *
1774     * <pre>
1775     * StringUtils.equals(null, null)   = true
1776     * StringUtils.equals(null, "abc")  = false
1777     * StringUtils.equals("abc", null)  = false
1778     * StringUtils.equals("abc", "abc") = true
1779     * StringUtils.equals("abc", "ABC") = false
1780     * </pre>
1781     *
1782     * @param cs1  the first CharSequence, may be {@code null}
1783     * @param cs2  the second CharSequence, may be {@code null}
1784     * @return {@code true} if the CharSequences are equal (case-sensitive), or both {@code null}
1785     * @since 3.0 Changed signature from equals(String, String) to equals(CharSequence, CharSequence)
1786     * @see Object#equals(Object)
1787     * @see #equalsIgnoreCase(CharSequence, CharSequence)
1788     */
1789    public static boolean equals(final CharSequence cs1, final CharSequence cs2) {
1790        if (cs1 == cs2) {
1791            return true;
1792        }
1793        if (cs1 == null || cs2 == null) {
1794            return false;
1795        }
1796        if (cs1.length() != cs2.length()) {
1797            return false;
1798        }
1799        if (cs1 instanceof String && cs2 instanceof String) {
1800            return cs1.equals(cs2);
1801        }
1802        // Step-wise comparison
1803        final int length = cs1.length();
1804        for (int i = 0; i < length; i++) {
1805            if (cs1.charAt(i) != cs2.charAt(i)) {
1806                return false;
1807            }
1808        }
1809        return true;
1810    }
1811
1812    /**
1813     * Compares given {@code string} to a CharSequences vararg of {@code searchStrings},
1814     * returning {@code true} if the {@code string} is equal to any of the {@code searchStrings}.
1815     *
1816     * <pre>
1817     * StringUtils.equalsAny(null, (CharSequence[]) null) = false
1818     * StringUtils.equalsAny(null, null, null)    = true
1819     * StringUtils.equalsAny(null, "abc", "def")  = false
1820     * StringUtils.equalsAny("abc", null, "def")  = false
1821     * StringUtils.equalsAny("abc", "abc", "def") = true
1822     * StringUtils.equalsAny("abc", "ABC", "DEF") = false
1823     * </pre>
1824     *
1825     * @param string to compare, may be {@code null}.
1826     * @param searchStrings a vararg of strings, may be {@code null}.
1827     * @return {@code true} if the string is equal (case-sensitive) to any other element of {@code searchStrings};
1828     * {@code false} if {@code searchStrings} is null or contains no matches.
1829     * @since 3.5
1830     */
1831    public static boolean equalsAny(final CharSequence string, final CharSequence... searchStrings) {
1832        if (ArrayUtils.isNotEmpty(searchStrings)) {
1833            for (final CharSequence next : searchStrings) {
1834                if (equals(string, next)) {
1835                    return true;
1836                }
1837            }
1838        }
1839        return false;
1840    }
1841
1842    /**
1843     * Compares given {@code string} to a CharSequences vararg of {@code searchStrings},
1844     * returning {@code true} if the {@code string} is equal to any of the {@code searchStrings}, ignoring case.
1845     *
1846     * <pre>
1847     * StringUtils.equalsAnyIgnoreCase(null, (CharSequence[]) null) = false
1848     * StringUtils.equalsAnyIgnoreCase(null, null, null)    = true
1849     * StringUtils.equalsAnyIgnoreCase(null, "abc", "def")  = false
1850     * StringUtils.equalsAnyIgnoreCase("abc", null, "def")  = false
1851     * StringUtils.equalsAnyIgnoreCase("abc", "abc", "def") = true
1852     * StringUtils.equalsAnyIgnoreCase("abc", "ABC", "DEF") = true
1853     * </pre>
1854     *
1855     * @param string to compare, may be {@code null}.
1856     * @param searchStrings a vararg of strings, may be {@code null}.
1857     * @return {@code true} if the string is equal (case-insensitive) to any other element of {@code searchStrings};
1858     * {@code false} if {@code searchStrings} is null or contains no matches.
1859     * @since 3.5
1860     */
1861    public static boolean equalsAnyIgnoreCase(final CharSequence string, final CharSequence...searchStrings) {
1862        if (ArrayUtils.isNotEmpty(searchStrings)) {
1863            for (final CharSequence next : searchStrings) {
1864                if (equalsIgnoreCase(string, next)) {
1865                    return true;
1866                }
1867            }
1868        }
1869        return false;
1870    }
1871
1872    /**
1873     * Compares two CharSequences, returning {@code true} if they represent
1874     * equal sequences of characters, ignoring case.
1875     *
1876     * <p>{@code null}s are handled without exceptions. Two {@code null}
1877     * references are considered equal. The comparison is <strong>case insensitive</strong>.</p>
1878     *
1879     * <pre>
1880     * StringUtils.equalsIgnoreCase(null, null)   = true
1881     * StringUtils.equalsIgnoreCase(null, "abc")  = false
1882     * StringUtils.equalsIgnoreCase("abc", null)  = false
1883     * StringUtils.equalsIgnoreCase("abc", "abc") = true
1884     * StringUtils.equalsIgnoreCase("abc", "ABC") = true
1885     * </pre>
1886     *
1887     * @param cs1  the first CharSequence, may be {@code null}
1888     * @param cs2  the second CharSequence, may be {@code null}
1889     * @return {@code true} if the CharSequences are equal (case-insensitive), or both {@code null}
1890     * @since 3.0 Changed signature from equalsIgnoreCase(String, String) to equalsIgnoreCase(CharSequence, CharSequence)
1891     * @see #equals(CharSequence, CharSequence)
1892     */
1893    public static boolean equalsIgnoreCase(final CharSequence cs1, final CharSequence cs2) {
1894        if (cs1 == cs2) {
1895            return true;
1896        }
1897        if (cs1 == null || cs2 == null) {
1898            return false;
1899        }
1900        if (cs1.length() != cs2.length()) {
1901            return false;
1902        }
1903        return CharSequenceUtils.regionMatches(cs1, true, 0, cs2, 0, cs1.length());
1904    }
1905
1906    /**
1907     * Returns the first value in the array which is not empty (""),
1908     * {@code null} or whitespace only.
1909     *
1910     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
1911     *
1912     * <p>If all values are blank or the array is {@code null}
1913     * or empty then {@code null} is returned.</p>
1914     *
1915     * <pre>
1916     * StringUtils.firstNonBlank(null, null, null)     = null
1917     * StringUtils.firstNonBlank(null, "", " ")        = null
1918     * StringUtils.firstNonBlank("abc")                = "abc"
1919     * StringUtils.firstNonBlank(null, "xyz")          = "xyz"
1920     * StringUtils.firstNonBlank(null, "", " ", "xyz") = "xyz"
1921     * StringUtils.firstNonBlank(null, "xyz", "abc")   = "xyz"
1922     * StringUtils.firstNonBlank()                     = null
1923     * </pre>
1924     *
1925     * @param <T> the specific kind of CharSequence
1926     * @param values  the values to test, may be {@code null} or empty
1927     * @return the first value from {@code values} which is not blank,
1928     *  or {@code null} if there are no non-blank values
1929     * @since 3.8
1930     */
1931    @SafeVarargs
1932    public static <T extends CharSequence> T firstNonBlank(final T... values) {
1933        if (values != null) {
1934            for (final T val : values) {
1935                if (isNotBlank(val)) {
1936                    return val;
1937                }
1938            }
1939        }
1940        return null;
1941    }
1942
1943    /**
1944     * Returns the first value in the array which is not empty.
1945     *
1946     * <p>If all values are empty or the array is {@code null}
1947     * or empty then {@code null} is returned.</p>
1948     *
1949     * <pre>
1950     * StringUtils.firstNonEmpty(null, null, null)   = null
1951     * StringUtils.firstNonEmpty(null, null, "")     = null
1952     * StringUtils.firstNonEmpty(null, "", " ")      = " "
1953     * StringUtils.firstNonEmpty("abc")              = "abc"
1954     * StringUtils.firstNonEmpty(null, "xyz")        = "xyz"
1955     * StringUtils.firstNonEmpty("", "xyz")          = "xyz"
1956     * StringUtils.firstNonEmpty(null, "xyz", "abc") = "xyz"
1957     * StringUtils.firstNonEmpty()                   = null
1958     * </pre>
1959     *
1960     * @param <T> the specific kind of CharSequence
1961     * @param values  the values to test, may be {@code null} or empty
1962     * @return the first value from {@code values} which is not empty,
1963     *  or {@code null} if there are no non-empty values
1964     * @since 3.8
1965     */
1966    @SafeVarargs
1967    public static <T extends CharSequence> T firstNonEmpty(final T... values) {
1968        if (values != null) {
1969            for (final T val : values) {
1970                if (isNotEmpty(val)) {
1971                    return val;
1972                }
1973            }
1974        }
1975        return null;
1976    }
1977
1978    /**
1979     * Calls {@link String#getBytes(Charset)} in a null-safe manner.
1980     *
1981     * @param string input string
1982     * @param charset The {@link Charset} to encode the {@link String}. If null, then use the default Charset.
1983     * @return The empty byte[] if {@code string} is null, the result of {@link String#getBytes(Charset)} otherwise.
1984     * @see String#getBytes(Charset)
1985     * @since 3.10
1986     */
1987    public static byte[] getBytes(final String string, final Charset charset) {
1988        return string == null ? ArrayUtils.EMPTY_BYTE_ARRAY : string.getBytes(Charsets.toCharset(charset));
1989    }
1990
1991    /**
1992     * Calls {@link String#getBytes(String)} in a null-safe manner.
1993     *
1994     * @param string input string
1995     * @param charset The {@link Charset} name to encode the {@link String}. If null, then use the default Charset.
1996     * @return The empty byte[] if {@code string} is null, the result of {@link String#getBytes(String)} otherwise.
1997     * @throws UnsupportedEncodingException Thrown when the named charset is not supported.
1998     * @see String#getBytes(String)
1999     * @since 3.10
2000     */
2001    public static byte[] getBytes(final String string, final String charset) throws UnsupportedEncodingException {
2002        return string == null ? ArrayUtils.EMPTY_BYTE_ARRAY : string.getBytes(Charsets.toCharsetName(charset));
2003    }
2004
2005    /**
2006     * Compares all Strings in an array and returns the initial sequence of
2007     * characters that is common to all of them.
2008     *
2009     * <p>For example,
2010     * {@code getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) -&gt; "i am a "}</p>
2011     *
2012     * <pre>
2013     * StringUtils.getCommonPrefix(null) = ""
2014     * StringUtils.getCommonPrefix(new String[] {}) = ""
2015     * StringUtils.getCommonPrefix(new String[] {"abc"}) = "abc"
2016     * StringUtils.getCommonPrefix(new String[] {null, null}) = ""
2017     * StringUtils.getCommonPrefix(new String[] {"", ""}) = ""
2018     * StringUtils.getCommonPrefix(new String[] {"", null}) = ""
2019     * StringUtils.getCommonPrefix(new String[] {"abc", null, null}) = ""
2020     * StringUtils.getCommonPrefix(new String[] {null, null, "abc"}) = ""
2021     * StringUtils.getCommonPrefix(new String[] {"", "abc"}) = ""
2022     * StringUtils.getCommonPrefix(new String[] {"abc", ""}) = ""
2023     * StringUtils.getCommonPrefix(new String[] {"abc", "abc"}) = "abc"
2024     * StringUtils.getCommonPrefix(new String[] {"abc", "a"}) = "a"
2025     * StringUtils.getCommonPrefix(new String[] {"ab", "abxyz"}) = "ab"
2026     * StringUtils.getCommonPrefix(new String[] {"abcde", "abxyz"}) = "ab"
2027     * StringUtils.getCommonPrefix(new String[] {"abcde", "xyz"}) = ""
2028     * StringUtils.getCommonPrefix(new String[] {"xyz", "abcde"}) = ""
2029     * StringUtils.getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) = "i am a "
2030     * </pre>
2031     *
2032     * @param strs  array of String objects, entries may be null
2033     * @return the initial sequence of characters that are common to all Strings
2034     * in the array; empty String if the array is null, the elements are all null
2035     * or if there is no common prefix.
2036     * @since 2.4
2037     */
2038    public static String getCommonPrefix(final String... strs) {
2039        if (ArrayUtils.isEmpty(strs)) {
2040            return EMPTY;
2041        }
2042        final int smallestIndexOfDiff = indexOfDifference(strs);
2043        if (smallestIndexOfDiff == INDEX_NOT_FOUND) {
2044            // all strings were identical
2045            if (strs[0] == null) {
2046                return EMPTY;
2047            }
2048            return strs[0];
2049        }
2050        if (smallestIndexOfDiff == 0) {
2051            // there were no common initial characters
2052            return EMPTY;
2053        }
2054        // we found a common initial character sequence
2055        return strs[0].substring(0, smallestIndexOfDiff);
2056    }
2057
2058    /**
2059     * Checks if a String {@code str} contains Unicode digits,
2060     * if yes then concatenate all the digits in {@code str} and return it as a String.
2061     *
2062     * <p>An empty ("") String will be returned if no digits found in {@code str}.</p>
2063     *
2064     * <pre>
2065     * StringUtils.getDigits(null)  = null
2066     * StringUtils.getDigits("")    = ""
2067     * StringUtils.getDigits("abc") = ""
2068     * StringUtils.getDigits("1000$") = "1000"
2069     * StringUtils.getDigits("1123~45") = "112345"
2070     * StringUtils.getDigits("(541) 754-3010") = "5417543010"
2071     * StringUtils.getDigits("\u0967\u0968\u0969") = "\u0967\u0968\u0969"
2072     * </pre>
2073     *
2074     * @param str the String to extract digits from, may be null
2075     * @return String with only digits,
2076     *           or an empty ("") String if no digits found,
2077     *           or {@code null} String if {@code str} is null
2078     * @since 3.6
2079     */
2080    public static String getDigits(final String str) {
2081        if (isEmpty(str)) {
2082            return str;
2083        }
2084        final int sz = str.length();
2085        final StringBuilder strDigits = new StringBuilder(sz);
2086        for (int i = 0; i < sz; i++) {
2087            final char tempChar = str.charAt(i);
2088            if (Character.isDigit(tempChar)) {
2089                strDigits.append(tempChar);
2090            }
2091        }
2092        return strDigits.toString();
2093    }
2094
2095    /**
2096     * Find the Fuzzy Distance which indicates the similarity score between two Strings.
2097     *
2098     * <p>This string matching algorithm is similar to the algorithms of editors such as Sublime Text,
2099     * TextMate, Atom and others. One point is given for every matched character. Subsequent
2100     * matches yield two bonus points. A higher score indicates a higher similarity.</p>
2101     *
2102     * <pre>
2103     * StringUtils.getFuzzyDistance(null, null, null)                                    = IllegalArgumentException
2104     * StringUtils.getFuzzyDistance("", "", Locale.ENGLISH)                              = 0
2105     * StringUtils.getFuzzyDistance("Workshop", "b", Locale.ENGLISH)                     = 0
2106     * StringUtils.getFuzzyDistance("Room", "o", Locale.ENGLISH)                         = 1
2107     * StringUtils.getFuzzyDistance("Workshop", "w", Locale.ENGLISH)                     = 1
2108     * StringUtils.getFuzzyDistance("Workshop", "ws", Locale.ENGLISH)                    = 2
2109     * StringUtils.getFuzzyDistance("Workshop", "wo", Locale.ENGLISH)                    = 4
2110     * StringUtils.getFuzzyDistance("Apache Software Foundation", "asf", Locale.ENGLISH) = 3
2111     * </pre>
2112     *
2113     * @param term a full term that should be matched against, must not be null
2114     * @param query the query that will be matched against a term, must not be null
2115     * @param locale This string matching logic is case-insensitive. A locale is necessary to normalize
2116     *  both Strings to lower case.
2117     * @return result score
2118     * @throws IllegalArgumentException if either String input {@code null} or Locale input {@code null}
2119     * @since 3.4
2120     * @deprecated As of 3.6, use Apache Commons Text
2121     * <a href="https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/similarity/FuzzyScore.html">
2122     * FuzzyScore</a> instead
2123     */
2124    @Deprecated
2125    public static int getFuzzyDistance(final CharSequence term, final CharSequence query, final Locale locale) {
2126        if (term == null || query == null) {
2127            throw new IllegalArgumentException("Strings must not be null");
2128        }
2129        if (locale == null) {
2130            throw new IllegalArgumentException("Locale must not be null");
2131        }
2132
2133        // fuzzy logic is case-insensitive. We normalize the Strings to lower
2134        // case right from the start. Turning characters to lower case
2135        // via Character.toLowerCase(char) is unfortunately insufficient
2136        // as it does not accept a locale.
2137        final String termLowerCase = term.toString().toLowerCase(locale);
2138        final String queryLowerCase = query.toString().toLowerCase(locale);
2139
2140        // the resulting score
2141        int score = 0;
2142
2143        // the position in the term which will be scanned next for potential
2144        // query character matches
2145        int termIndex = 0;
2146
2147        // index of the previously matched character in the term
2148        int previousMatchingCharacterIndex = Integer.MIN_VALUE;
2149
2150        for (int queryIndex = 0; queryIndex < queryLowerCase.length(); queryIndex++) {
2151            final char queryChar = queryLowerCase.charAt(queryIndex);
2152
2153            boolean termCharacterMatchFound = false;
2154            for (; termIndex < termLowerCase.length() && !termCharacterMatchFound; termIndex++) {
2155                final char termChar = termLowerCase.charAt(termIndex);
2156
2157                if (queryChar == termChar) {
2158                    // simple character matches result in one point
2159                    score++;
2160
2161                    // subsequent character matches further improve
2162                    // the score.
2163                    if (previousMatchingCharacterIndex + 1 == termIndex) {
2164                        score += 2;
2165                    }
2166
2167                    previousMatchingCharacterIndex = termIndex;
2168
2169                    // we can leave the nested loop. Every character in the
2170                    // query can match at most one character in the term.
2171                    termCharacterMatchFound = true;
2172                }
2173            }
2174        }
2175
2176        return score;
2177    }
2178
2179    /**
2180     * Returns either the passed in CharSequence, or if the CharSequence is
2181     * whitespace, empty ("") or {@code null}, the value supplied by {@code defaultStrSupplier}.
2182     *
2183     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
2184     *
2185     * <p>Caller responsible for thread-safety and exception handling of default value supplier</p>
2186     *
2187     * <pre>
2188     * {@code
2189     * StringUtils.getIfBlank(null, () -> "NULL")   = "NULL"
2190     * StringUtils.getIfBlank("", () -> "NULL")     = "NULL"
2191     * StringUtils.getIfBlank(" ", () -> "NULL")    = "NULL"
2192     * StringUtils.getIfBlank("bat", () -> "NULL")  = "bat"
2193     * StringUtils.getIfBlank("", () -> null)       = null
2194     * StringUtils.getIfBlank("", null)             = null
2195     * }</pre>
2196     * @param <T> the specific kind of CharSequence
2197     * @param str the CharSequence to check, may be null
2198     * @param defaultSupplier the supplier of default CharSequence to return
2199     *  if the input is whitespace, empty ("") or {@code null}, may be null
2200     * @return the passed in CharSequence, or the default
2201     * @see StringUtils#defaultString(String, String)
2202     * @since 3.10
2203     */
2204    public static <T extends CharSequence> T getIfBlank(final T str, final Supplier<T> defaultSupplier) {
2205        return isBlank(str) ? Suppliers.get(defaultSupplier) : str;
2206    }
2207
2208    /**
2209     * Returns either the passed in CharSequence, or if the CharSequence is
2210     * empty or {@code null}, the value supplied by {@code defaultStrSupplier}.
2211     *
2212     * <p>Caller responsible for thread-safety and exception handling of default value supplier</p>
2213     *
2214     * <pre>
2215     * {@code
2216     * StringUtils.getIfEmpty(null, () -> "NULL")    = "NULL"
2217     * StringUtils.getIfEmpty("", () -> "NULL")      = "NULL"
2218     * StringUtils.getIfEmpty(" ", () -> "NULL")     = " "
2219     * StringUtils.getIfEmpty("bat", () -> "NULL")   = "bat"
2220     * StringUtils.getIfEmpty("", () -> null)        = null
2221     * StringUtils.getIfEmpty("", null)              = null
2222     * }
2223     * </pre>
2224     * @param <T> the specific kind of CharSequence
2225     * @param str  the CharSequence to check, may be null
2226     * @param defaultSupplier  the supplier of default CharSequence to return
2227     *  if the input is empty ("") or {@code null}, may be null
2228     * @return the passed in CharSequence, or the default
2229     * @see StringUtils#defaultString(String, String)
2230     * @since 3.10
2231     */
2232    public static <T extends CharSequence> T getIfEmpty(final T str, final Supplier<T> defaultSupplier) {
2233        return isEmpty(str) ? Suppliers.get(defaultSupplier) : str;
2234    }
2235
2236    /**
2237     * Find the Jaro Winkler Distance which indicates the similarity score between two Strings.
2238     *
2239     * <p>The Jaro measure is the weighted sum of percentage of matched characters from each file and transposed characters.
2240     * Winkler increased this measure for matching initial characters.</p>
2241     *
2242     * <p>This implementation is based on the Jaro Winkler similarity algorithm
2243     * from <a href="https://en.wikipedia.org/wiki/Jaro%E2%80%93Winkler_distance">https://en.wikipedia.org/wiki/Jaro%E2%80%93Winkler_distance</a>.</p>
2244     *
2245     * <pre>
2246     * StringUtils.getJaroWinklerDistance(null, null)          = IllegalArgumentException
2247     * StringUtils.getJaroWinklerDistance("", "")              = 0.0
2248     * StringUtils.getJaroWinklerDistance("", "a")             = 0.0
2249     * StringUtils.getJaroWinklerDistance("aaapppp", "")       = 0.0
2250     * StringUtils.getJaroWinklerDistance("frog", "fog")       = 0.93
2251     * StringUtils.getJaroWinklerDistance("fly", "ant")        = 0.0
2252     * StringUtils.getJaroWinklerDistance("elephant", "hippo") = 0.44
2253     * StringUtils.getJaroWinklerDistance("hippo", "elephant") = 0.44
2254     * StringUtils.getJaroWinklerDistance("hippo", "zzzzzzzz") = 0.0
2255     * StringUtils.getJaroWinklerDistance("hello", "hallo")    = 0.88
2256     * StringUtils.getJaroWinklerDistance("ABC Corporation", "ABC Corp") = 0.93
2257     * StringUtils.getJaroWinklerDistance("D N H Enterprises Inc", "D &amp; H Enterprises, Inc.") = 0.95
2258     * StringUtils.getJaroWinklerDistance("My Gym Children's Fitness Center", "My Gym. Childrens Fitness") = 0.92
2259     * StringUtils.getJaroWinklerDistance("PENNSYLVANIA", "PENNCISYLVNIA") = 0.88
2260     * </pre>
2261     *
2262     * @param first the first String, must not be null
2263     * @param second the second String, must not be null
2264     * @return result distance
2265     * @throws IllegalArgumentException if either String input {@code null}
2266     * @since 3.3
2267     * @deprecated As of 3.6, use Apache Commons Text
2268     * <a href="https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/similarity/JaroWinklerDistance.html">
2269     * JaroWinklerDistance</a> instead
2270     */
2271    @Deprecated
2272    public static double getJaroWinklerDistance(final CharSequence first, final CharSequence second) {
2273        final double DEFAULT_SCALING_FACTOR = 0.1;
2274
2275        if (first == null || second == null) {
2276            throw new IllegalArgumentException("Strings must not be null");
2277        }
2278
2279        final int[] mtp = matches(first, second);
2280        final double m = mtp[0];
2281        if (m == 0) {
2282            return 0D;
2283        }
2284        final double j = (m / first.length() + m / second.length() + (m - mtp[1]) / m) / 3;
2285        final double jw = j < 0.7D ? j : j + Math.min(DEFAULT_SCALING_FACTOR, 1D / mtp[3]) * mtp[2] * (1D - j);
2286        return Math.round(jw * 100.0D) / 100.0D;
2287    }
2288
2289    /**
2290     * Find the Levenshtein distance between two Strings.
2291     *
2292     * <p>This is the number of changes needed to change one String into
2293     * another, where each change is a single character modification (deletion,
2294     * insertion or substitution).</p>
2295     *
2296     * <p>The implementation uses a single-dimensional array of length s.length() + 1. See
2297     * <a href="https://blog.softwx.net/2014/12/optimizing-levenshtein-algorithm-in-c.html">
2298     * https://blog.softwx.net/2014/12/optimizing-levenshtein-algorithm-in-c.html</a> for details.</p>
2299     *
2300     * <pre>
2301     * StringUtils.getLevenshteinDistance(null, *)             = IllegalArgumentException
2302     * StringUtils.getLevenshteinDistance(*, null)             = IllegalArgumentException
2303     * StringUtils.getLevenshteinDistance("", "")              = 0
2304     * StringUtils.getLevenshteinDistance("", "a")             = 1
2305     * StringUtils.getLevenshteinDistance("aaapppp", "")       = 7
2306     * StringUtils.getLevenshteinDistance("frog", "fog")       = 1
2307     * StringUtils.getLevenshteinDistance("fly", "ant")        = 3
2308     * StringUtils.getLevenshteinDistance("elephant", "hippo") = 7
2309     * StringUtils.getLevenshteinDistance("hippo", "elephant") = 7
2310     * StringUtils.getLevenshteinDistance("hippo", "zzzzzzzz") = 8
2311     * StringUtils.getLevenshteinDistance("hello", "hallo")    = 1
2312     * </pre>
2313     *
2314     * @param s  the first String, must not be null
2315     * @param t  the second String, must not be null
2316     * @return result distance
2317     * @throws IllegalArgumentException if either String input {@code null}
2318     * @since 3.0 Changed signature from getLevenshteinDistance(String, String) to
2319     * getLevenshteinDistance(CharSequence, CharSequence)
2320     * @deprecated As of 3.6, use Apache Commons Text
2321     * <a href="https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/similarity/LevenshteinDistance.html">
2322     * LevenshteinDistance</a> instead
2323     */
2324    @Deprecated
2325    public static int getLevenshteinDistance(CharSequence s, CharSequence t) {
2326        if (s == null || t == null) {
2327            throw new IllegalArgumentException("Strings must not be null");
2328        }
2329
2330        int n = s.length();
2331        int m = t.length();
2332
2333        if (n == 0) {
2334            return m;
2335        }
2336        if (m == 0) {
2337            return n;
2338        }
2339
2340        if (n > m) {
2341            // swap the input strings to consume less memory
2342            final CharSequence tmp = s;
2343            s = t;
2344            t = tmp;
2345            n = m;
2346            m = t.length();
2347        }
2348
2349        final int[] p = new int[n + 1];
2350        // indexes into strings s and t
2351        int i; // iterates through s
2352        int j; // iterates through t
2353        int upperleft;
2354        int upper;
2355
2356        char jOfT; // jth character of t
2357        int cost;
2358
2359        for (i = 0; i <= n; i++) {
2360            p[i] = i;
2361        }
2362
2363        for (j = 1; j <= m; j++) {
2364            upperleft = p[0];
2365            jOfT = t.charAt(j - 1);
2366            p[0] = j;
2367
2368            for (i = 1; i <= n; i++) {
2369                upper = p[i];
2370                cost = s.charAt(i - 1) == jOfT ? 0 : 1;
2371                // minimum of cell to the left+1, to the top+1, diagonally left and up +cost
2372                p[i] = Math.min(Math.min(p[i - 1] + 1, p[i] + 1), upperleft + cost);
2373                upperleft = upper;
2374            }
2375        }
2376
2377        return p[n];
2378    }
2379
2380    /**
2381     * Find the Levenshtein distance between two Strings if it's less than or equal to a given
2382     * threshold.
2383     *
2384     * <p>This is the number of changes needed to change one String into
2385     * another, where each change is a single character modification (deletion,
2386     * insertion or substitution).</p>
2387     *
2388     * <p>This implementation follows from Algorithms on Strings, Trees and Sequences by Dan Gusfield
2389     * and Chas Emerick's implementation of the Levenshtein distance algorithm from
2390     * <a href="https://web.archive.org/web/20120212021906/http%3A//www.merriampark.com/ld.htm">http://www.merriampark.com/ld.htm</a></p>
2391     *
2392     * <pre>
2393     * StringUtils.getLevenshteinDistance(null, *, *)             = IllegalArgumentException
2394     * StringUtils.getLevenshteinDistance(*, null, *)             = IllegalArgumentException
2395     * StringUtils.getLevenshteinDistance(*, *, -1)               = IllegalArgumentException
2396     * StringUtils.getLevenshteinDistance("", "", 0)              = 0
2397     * StringUtils.getLevenshteinDistance("aaapppp", "", 8)       = 7
2398     * StringUtils.getLevenshteinDistance("aaapppp", "", 7)       = 7
2399     * StringUtils.getLevenshteinDistance("aaapppp", "", 6))      = -1
2400     * StringUtils.getLevenshteinDistance("elephant", "hippo", 7) = 7
2401     * StringUtils.getLevenshteinDistance("elephant", "hippo", 6) = -1
2402     * StringUtils.getLevenshteinDistance("hippo", "elephant", 7) = 7
2403     * StringUtils.getLevenshteinDistance("hippo", "elephant", 6) = -1
2404     * </pre>
2405     *
2406     * @param s  the first String, must not be null
2407     * @param t  the second String, must not be null
2408     * @param threshold the target threshold, must not be negative
2409     * @return result distance, or {@code -1} if the distance would be greater than the threshold
2410     * @throws IllegalArgumentException if either String input {@code null} or negative threshold
2411     * @deprecated As of 3.6, use Apache Commons Text
2412     * <a href="https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/similarity/LevenshteinDistance.html">
2413     * LevenshteinDistance</a> instead
2414     */
2415    @Deprecated
2416    public static int getLevenshteinDistance(CharSequence s, CharSequence t, final int threshold) {
2417        if (s == null || t == null) {
2418            throw new IllegalArgumentException("Strings must not be null");
2419        }
2420        if (threshold < 0) {
2421            throw new IllegalArgumentException("Threshold must not be negative");
2422        }
2423
2424        /*
2425        This implementation only computes the distance if it's less than or equal to the
2426        threshold value, returning -1 if it's greater.  The advantage is performance: unbounded
2427        distance is O(nm), but a bound of k allows us to reduce it to O(km) time by only
2428        computing a diagonal stripe of width 2k + 1 of the cost table.
2429        It is also possible to use this to compute the unbounded Levenshtein distance by starting
2430        the threshold at 1 and doubling each time until the distance is found; this is O(dm), where
2431        d is the distance.
2432
2433        One subtlety comes from needing to ignore entries on the border of our stripe
2434        eg.
2435        p[] = |#|#|#|*
2436        d[] =  *|#|#|#|
2437        We must ignore the entry to the left of the leftmost member
2438        We must ignore the entry above the rightmost member
2439
2440        Another subtlety comes from our stripe running off the matrix if the strings aren't
2441        of the same size.  Since string s is always swapped to be the shorter of the two,
2442        the stripe will always run off to the upper right instead of the lower left of the matrix.
2443
2444        As a concrete example, suppose s is of length 5, t is of length 7, and our threshold is 1.
2445        In this case we're going to walk a stripe of length 3.  The matrix would look like so:
2446
2447           1 2 3 4 5
2448        1 |#|#| | | |
2449        2 |#|#|#| | |
2450        3 | |#|#|#| |
2451        4 | | |#|#|#|
2452        5 | | | |#|#|
2453        6 | | | | |#|
2454        7 | | | | | |
2455
2456        Note how the stripe leads off the table as there is no possible way to turn a string of length 5
2457        into one of length 7 in edit distance of 1.
2458
2459        Additionally, this implementation decreases memory usage by using two
2460        single-dimensional arrays and swapping them back and forth instead of allocating
2461        an entire n by m matrix.  This requires a few minor changes, such as immediately returning
2462        when it's detected that the stripe has run off the matrix and initially filling the arrays with
2463        large values so that entries we don't compute are ignored.
2464
2465        See Algorithms on Strings, Trees and Sequences by Dan Gusfield for some discussion.
2466         */
2467
2468        int n = s.length(); // length of s
2469        int m = t.length(); // length of t
2470
2471        // if one string is empty, the edit distance is necessarily the length of the other
2472        if (n == 0) {
2473            return m <= threshold ? m : -1;
2474        }
2475        if (m == 0) {
2476            return n <= threshold ? n : -1;
2477        }
2478        if (Math.abs(n - m) > threshold) {
2479            // no need to calculate the distance if the length difference is greater than the threshold
2480            return -1;
2481        }
2482
2483        if (n > m) {
2484            // swap the two strings to consume less memory
2485            final CharSequence tmp = s;
2486            s = t;
2487            t = tmp;
2488            n = m;
2489            m = t.length();
2490        }
2491
2492        int[] p = new int[n + 1]; // 'previous' cost array, horizontally
2493        int[] d = new int[n + 1]; // cost array, horizontally
2494        int[] tmp; // placeholder to assist in swapping p and d
2495
2496        // fill in starting table values
2497        final int boundary = Math.min(n, threshold) + 1;
2498        for (int i = 0; i < boundary; i++) {
2499            p[i] = i;
2500        }
2501        // these fills ensure that the value above the rightmost entry of our
2502        // stripe will be ignored in following loop iterations
2503        Arrays.fill(p, boundary, p.length, Integer.MAX_VALUE);
2504        Arrays.fill(d, Integer.MAX_VALUE);
2505
2506        // iterates through t
2507        for (int j = 1; j <= m; j++) {
2508            final char jOfT = t.charAt(j - 1); // jth character of t
2509            d[0] = j;
2510
2511            // compute stripe indices, constrain to array size
2512            final int min = Math.max(1, j - threshold);
2513            final int max = j > Integer.MAX_VALUE - threshold ? n : Math.min(n, j + threshold);
2514
2515            // the stripe may lead off of the table if s and t are of different sizes
2516            if (min > max) {
2517                return -1;
2518            }
2519
2520            // ignore entry left of leftmost
2521            if (min > 1) {
2522                d[min - 1] = Integer.MAX_VALUE;
2523            }
2524
2525            // iterates through [min, max] in s
2526            for (int i = min; i <= max; i++) {
2527                if (s.charAt(i - 1) == jOfT) {
2528                    // diagonally left and up
2529                    d[i] = p[i - 1];
2530                } else {
2531                    // 1 + minimum of cell to the left, to the top, diagonally left and up
2532                    d[i] = 1 + Math.min(Math.min(d[i - 1], p[i]), p[i - 1]);
2533                }
2534            }
2535
2536            // copy current distance counts to 'previous row' distance counts
2537            tmp = p;
2538            p = d;
2539            d = tmp;
2540        }
2541
2542        // if p[n] is greater than the threshold, there's no guarantee on it being the correct
2543        // distance
2544        if (p[n] <= threshold) {
2545            return p[n];
2546        }
2547        return -1;
2548    }
2549
2550    /**
2551     * Finds the first index within a CharSequence, handling {@code null}.
2552     * This method uses {@link String#indexOf(String, int)} if possible.
2553     *
2554     * <p>A {@code null} CharSequence will return {@code -1}.</p>
2555     *
2556     * <pre>
2557     * StringUtils.indexOf(null, *)          = -1
2558     * StringUtils.indexOf(*, null)          = -1
2559     * StringUtils.indexOf("", "")           = 0
2560     * StringUtils.indexOf("", *)            = -1 (except when * = "")
2561     * StringUtils.indexOf("aabaabaa", "a")  = 0
2562     * StringUtils.indexOf("aabaabaa", "b")  = 2
2563     * StringUtils.indexOf("aabaabaa", "ab") = 1
2564     * StringUtils.indexOf("aabaabaa", "")   = 0
2565     * </pre>
2566     *
2567     * @param seq  the CharSequence to check, may be null
2568     * @param searchSeq  the CharSequence to find, may be null
2569     * @return the first index of the search CharSequence,
2570     *  -1 if no match or {@code null} string input
2571     * @since 2.0
2572     * @since 3.0 Changed signature from indexOf(String, String) to indexOf(CharSequence, CharSequence)
2573     */
2574    public static int indexOf(final CharSequence seq, final CharSequence searchSeq) {
2575        if (seq == null || searchSeq == null) {
2576            return INDEX_NOT_FOUND;
2577        }
2578        return CharSequenceUtils.indexOf(seq, searchSeq, 0);
2579    }
2580
2581    /**
2582     * Finds the first index within a CharSequence, handling {@code null}.
2583     * This method uses {@link String#indexOf(String, int)} if possible.
2584     *
2585     * <p>A {@code null} CharSequence will return {@code -1}.
2586     * A negative start position is treated as zero.
2587     * An empty ("") search CharSequence always matches.
2588     * A start position greater than the string length only matches
2589     * an empty search CharSequence.</p>
2590     *
2591     * <pre>
2592     * StringUtils.indexOf(null, *, *)          = -1
2593     * StringUtils.indexOf(*, null, *)          = -1
2594     * StringUtils.indexOf("", "", 0)           = 0
2595     * StringUtils.indexOf("", *, 0)            = -1 (except when * = "")
2596     * StringUtils.indexOf("aabaabaa", "a", 0)  = 0
2597     * StringUtils.indexOf("aabaabaa", "b", 0)  = 2
2598     * StringUtils.indexOf("aabaabaa", "ab", 0) = 1
2599     * StringUtils.indexOf("aabaabaa", "b", 3)  = 5
2600     * StringUtils.indexOf("aabaabaa", "b", 9)  = -1
2601     * StringUtils.indexOf("aabaabaa", "b", -1) = 2
2602     * StringUtils.indexOf("aabaabaa", "", 2)   = 2
2603     * StringUtils.indexOf("abc", "", 9)        = 3
2604     * </pre>
2605     *
2606     * @param seq  the CharSequence to check, may be null
2607     * @param searchSeq  the CharSequence to find, may be null
2608     * @param startPos  the start position, negative treated as zero
2609     * @return the first index of the search CharSequence (always &ge; startPos),
2610     *  -1 if no match or {@code null} string input
2611     * @since 2.0
2612     * @since 3.0 Changed signature from indexOf(String, String, int) to indexOf(CharSequence, CharSequence, int)
2613     */
2614    public static int indexOf(final CharSequence seq, final CharSequence searchSeq, final int startPos) {
2615        if (seq == null || searchSeq == null) {
2616            return INDEX_NOT_FOUND;
2617        }
2618        return CharSequenceUtils.indexOf(seq, searchSeq, startPos);
2619    }
2620
2621    /**
2622     * Returns the index within {@code seq} of the first occurrence of
2623     * the specified character. If a character with value
2624     * {@code searchChar} occurs in the character sequence represented by
2625     * {@code seq} {@link CharSequence} object, then the index (in Unicode
2626     * code units) of the first such occurrence is returned. For
2627     * values of {@code searchChar} in the range from 0 to 0xFFFF
2628     * (inclusive), this is the smallest value <i>k</i> such that:
2629     * <blockquote><pre>
2630     * this.charAt(<i>k</i>) == searchChar
2631     * </pre></blockquote>
2632     * is true. For other values of {@code searchChar}, it is the
2633     * smallest value <i>k</i> such that:
2634     * <blockquote><pre>
2635     * this.codePointAt(<i>k</i>) == searchChar
2636     * </pre></blockquote>
2637     * is true. In either case, if no such character occurs in {@code seq},
2638     * then {@code INDEX_NOT_FOUND (-1)} is returned.
2639     *
2640     * <p>Furthermore, a {@code null} or empty ("") CharSequence will
2641     * return {@code INDEX_NOT_FOUND (-1)}.</p>
2642     *
2643     * <pre>
2644     * StringUtils.indexOf(null, *)         = -1
2645     * StringUtils.indexOf("", *)           = -1
2646     * StringUtils.indexOf("aabaabaa", 'a') = 0
2647     * StringUtils.indexOf("aabaabaa", 'b') = 2
2648     * </pre>
2649     *
2650     * @param seq  the CharSequence to check, may be null
2651     * @param searchChar  the character to find
2652     * @return the first index of the search character,
2653     *  -1 if no match or {@code null} string input
2654     * @since 2.0
2655     * @since 3.0 Changed signature from indexOf(String, int) to indexOf(CharSequence, int)
2656     * @since 3.6 Updated {@link CharSequenceUtils} call to behave more like {@link String}
2657     */
2658    public static int indexOf(final CharSequence seq, final int searchChar) {
2659        if (isEmpty(seq)) {
2660            return INDEX_NOT_FOUND;
2661        }
2662        return CharSequenceUtils.indexOf(seq, searchChar, 0);
2663    }
2664
2665    /**
2666     * Returns the index within {@code seq} of the first occurrence of the
2667     * specified character, starting the search at the specified index.
2668     * <p>
2669     * If a character with value {@code searchChar} occurs in the
2670     * character sequence represented by the {@code seq} {@link CharSequence}
2671     * object at an index no smaller than {@code startPos}, then
2672     * the index of the first such occurrence is returned. For values
2673     * of {@code searchChar} in the range from 0 to 0xFFFF (inclusive),
2674     * this is the smallest value <i>k</i> such that:
2675     * <blockquote><pre>
2676     * (this.charAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &gt;= startPos)
2677     * </pre></blockquote>
2678     * is true. For other values of {@code searchChar}, it is the
2679     * smallest value <i>k</i> such that:
2680     * <blockquote><pre>
2681     * (this.codePointAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &gt;= startPos)
2682     * </pre></blockquote>
2683     * is true. In either case, if no such character occurs in {@code seq}
2684     * at or after position {@code startPos}, then
2685     * {@code -1} is returned.
2686     *
2687     * <p>
2688     * There is no restriction on the value of {@code startPos}. If it
2689     * is negative, it has the same effect as if it were zero: this entire
2690     * string may be searched. If it is greater than the length of this
2691     * string, it has the same effect as if it were equal to the length of
2692     * this string: {@code (INDEX_NOT_FOUND) -1} is returned. Furthermore, a
2693     * {@code null} or empty ("") CharSequence will
2694     * return {@code (INDEX_NOT_FOUND) -1}.
2695     *
2696     * <p>All indices are specified in {@code char} values
2697     * (Unicode code units).
2698     *
2699     * <pre>
2700     * StringUtils.indexOf(null, *, *)          = -1
2701     * StringUtils.indexOf("", *, *)            = -1
2702     * StringUtils.indexOf("aabaabaa", 'b', 0)  = 2
2703     * StringUtils.indexOf("aabaabaa", 'b', 3)  = 5
2704     * StringUtils.indexOf("aabaabaa", 'b', 9)  = -1
2705     * StringUtils.indexOf("aabaabaa", 'b', -1) = 2
2706     * </pre>
2707     *
2708     * @param seq  the CharSequence to check, may be null
2709     * @param searchChar  the character to find
2710     * @param startPos  the start position, negative treated as zero
2711     * @return the first index of the search character (always &ge; startPos),
2712     *  -1 if no match or {@code null} string input
2713     * @since 2.0
2714     * @since 3.0 Changed signature from indexOf(String, int, int) to indexOf(CharSequence, int, int)
2715     * @since 3.6 Updated {@link CharSequenceUtils} call to behave more like {@link String}
2716     */
2717    public static int indexOf(final CharSequence seq, final int searchChar, final int startPos) {
2718        if (isEmpty(seq)) {
2719            return INDEX_NOT_FOUND;
2720        }
2721        return CharSequenceUtils.indexOf(seq, searchChar, startPos);
2722    }
2723
2724    /**
2725     * Search a CharSequence to find the first index of any
2726     * character in the given set of characters.
2727     *
2728     * <p>A {@code null} String will return {@code -1}.
2729     * A {@code null} or zero length search array will return {@code -1}.</p>
2730     *
2731     * <pre>
2732     * StringUtils.indexOfAny(null, *)                  = -1
2733     * StringUtils.indexOfAny("", *)                    = -1
2734     * StringUtils.indexOfAny(*, null)                  = -1
2735     * StringUtils.indexOfAny(*, [])                    = -1
2736     * StringUtils.indexOfAny("zzabyycdxx", ['z', 'a']) = 0
2737     * StringUtils.indexOfAny("zzabyycdxx", ['b', 'y']) = 3
2738     * StringUtils.indexOfAny("aba", ['z'])             = -1
2739     * </pre>
2740     *
2741     * @param cs  the CharSequence to check, may be null
2742     * @param searchChars  the chars to search for, may be null
2743     * @return the index of any of the chars, -1 if no match or null input
2744     * @since 2.0
2745     * @since 3.0 Changed signature from indexOfAny(String, char[]) to indexOfAny(CharSequence, char...)
2746     */
2747    public static int indexOfAny(final CharSequence cs, final char... searchChars) {
2748        if (isEmpty(cs) || ArrayUtils.isEmpty(searchChars)) {
2749            return INDEX_NOT_FOUND;
2750        }
2751        final int csLen = cs.length();
2752        final int csLast = csLen - 1;
2753        final int searchLen = searchChars.length;
2754        final int searchLast = searchLen - 1;
2755        for (int i = 0; i < csLen; i++) {
2756            final char ch = cs.charAt(i);
2757            for (int j = 0; j < searchLen; j++) {
2758                if (searchChars[j] == ch) {
2759                    if (i >= csLast || j >= searchLast || !Character.isHighSurrogate(ch)) {
2760                        return i;
2761                    }
2762                    // ch is a supplementary character
2763                    if (searchChars[j + 1] == cs.charAt(i + 1)) {
2764                        return i;
2765                    }
2766                }
2767            }
2768        }
2769        return INDEX_NOT_FOUND;
2770    }
2771
2772    /**
2773     * Find the first index of any of a set of potential substrings.
2774     *
2775     * <p>A {@code null} CharSequence will return {@code -1}.
2776     * A {@code null} or zero length search array will return {@code -1}.
2777     * A {@code null} search array entry will be ignored, but a search
2778     * array containing "" will return {@code 0} if {@code str} is not
2779     * null. This method uses {@link String#indexOf(String)} if possible.</p>
2780     *
2781     * <pre>
2782     * StringUtils.indexOfAny(null, *)                      = -1
2783     * StringUtils.indexOfAny(*, null)                      = -1
2784     * StringUtils.indexOfAny(*, [])                        = -1
2785     * StringUtils.indexOfAny("zzabyycdxx", ["ab", "cd"])   = 2
2786     * StringUtils.indexOfAny("zzabyycdxx", ["cd", "ab"])   = 2
2787     * StringUtils.indexOfAny("zzabyycdxx", ["mn", "op"])   = -1
2788     * StringUtils.indexOfAny("zzabyycdxx", ["zab", "aby"]) = 1
2789     * StringUtils.indexOfAny("zzabyycdxx", [""])           = 0
2790     * StringUtils.indexOfAny("", [""])                     = 0
2791     * StringUtils.indexOfAny("", ["a"])                    = -1
2792     * </pre>
2793     *
2794     * @param str  the CharSequence to check, may be null
2795     * @param searchStrs  the CharSequences to search for, may be null
2796     * @return the first index of any of the searchStrs in str, -1 if no match
2797     * @since 3.0 Changed signature from indexOfAny(String, String[]) to indexOfAny(CharSequence, CharSequence...)
2798     */
2799    public static int indexOfAny(final CharSequence str, final CharSequence... searchStrs) {
2800        if (str == null || searchStrs == null) {
2801            return INDEX_NOT_FOUND;
2802        }
2803
2804        // String's can't have a MAX_VALUEth index.
2805        int ret = Integer.MAX_VALUE;
2806
2807        int tmp;
2808        for (final CharSequence search : searchStrs) {
2809            if (search == null) {
2810                continue;
2811            }
2812            tmp = CharSequenceUtils.indexOf(str, search, 0);
2813            if (tmp == INDEX_NOT_FOUND) {
2814                continue;
2815            }
2816
2817            if (tmp < ret) {
2818                ret = tmp;
2819            }
2820        }
2821
2822        return ret == Integer.MAX_VALUE ? INDEX_NOT_FOUND : ret;
2823    }
2824
2825    /**
2826     * Search a CharSequence to find the first index of any
2827     * character in the given set of characters.
2828     *
2829     * <p>A {@code null} String will return {@code -1}.
2830     * A {@code null} search string will return {@code -1}.</p>
2831     *
2832     * <pre>
2833     * StringUtils.indexOfAny(null, *)            = -1
2834     * StringUtils.indexOfAny("", *)              = -1
2835     * StringUtils.indexOfAny(*, null)            = -1
2836     * StringUtils.indexOfAny(*, "")              = -1
2837     * StringUtils.indexOfAny("zzabyycdxx", "za") = 0
2838     * StringUtils.indexOfAny("zzabyycdxx", "by") = 3
2839     * StringUtils.indexOfAny("aba", "z")         = -1
2840     * </pre>
2841     *
2842     * @param cs  the CharSequence to check, may be null
2843     * @param searchChars  the chars to search for, may be null
2844     * @return the index of any of the chars, -1 if no match or null input
2845     * @since 2.0
2846     * @since 3.0 Changed signature from indexOfAny(String, String) to indexOfAny(CharSequence, String)
2847     */
2848    public static int indexOfAny(final CharSequence cs, final String searchChars) {
2849        if (isEmpty(cs) || isEmpty(searchChars)) {
2850            return INDEX_NOT_FOUND;
2851        }
2852        return indexOfAny(cs, searchChars.toCharArray());
2853    }
2854
2855    /**
2856     * Searches a CharSequence to find the first index of any
2857     * character not in the given set of characters.
2858     *
2859     * <p>A {@code null} CharSequence will return {@code -1}.
2860     * A {@code null} or zero length search array will return {@code -1}.</p>
2861     *
2862     * <pre>
2863     * StringUtils.indexOfAnyBut(null, *)                              = -1
2864     * StringUtils.indexOfAnyBut("", *)                                = -1
2865     * StringUtils.indexOfAnyBut(*, null)                              = -1
2866     * StringUtils.indexOfAnyBut(*, [])                                = -1
2867     * StringUtils.indexOfAnyBut("zzabyycdxx", new char[] {'z', 'a'} ) = 3
2868     * StringUtils.indexOfAnyBut("aba", new char[] {'z'} )             = 0
2869     * StringUtils.indexOfAnyBut("aba", new char[] {'a', 'b'} )        = -1
2870
2871     * </pre>
2872     *
2873     * @param cs  the CharSequence to check, may be null
2874     * @param searchChars  the chars to search for, may be null
2875     * @return the index of any of the chars, -1 if no match or null input
2876     * @since 2.0
2877     * @since 3.0 Changed signature from indexOfAnyBut(String, char[]) to indexOfAnyBut(CharSequence, char...)
2878     */
2879    public static int indexOfAnyBut(final CharSequence cs, final char... searchChars) {
2880        if (isEmpty(cs) || ArrayUtils.isEmpty(searchChars)) {
2881            return INDEX_NOT_FOUND;
2882        }
2883        final int csLen = cs.length();
2884        final int csLast = csLen - 1;
2885        final int searchLen = searchChars.length;
2886        final int searchLast = searchLen - 1;
2887        outer:
2888        for (int i = 0; i < csLen; i++) {
2889            final char ch = cs.charAt(i);
2890            for (int j = 0; j < searchLen; j++) {
2891                if (searchChars[j] == ch) {
2892                    if (i >= csLast || j >= searchLast || !Character.isHighSurrogate(ch)) {
2893                        continue outer;
2894                    }
2895                    if (searchChars[j + 1] == cs.charAt(i + 1)) {
2896                        continue outer;
2897                    }
2898                }
2899            }
2900            return i;
2901        }
2902        return INDEX_NOT_FOUND;
2903    }
2904
2905    /**
2906     * Search a CharSequence to find the first index of any
2907     * character not in the given set of characters.
2908     *
2909     * <p>A {@code null} CharSequence will return {@code -1}.
2910     * A {@code null} or empty search string will return {@code -1}.</p>
2911     *
2912     * <pre>
2913     * StringUtils.indexOfAnyBut(null, *)            = -1
2914     * StringUtils.indexOfAnyBut("", *)              = -1
2915     * StringUtils.indexOfAnyBut(*, null)            = -1
2916     * StringUtils.indexOfAnyBut(*, "")              = -1
2917     * StringUtils.indexOfAnyBut("zzabyycdxx", "za") = 3
2918     * StringUtils.indexOfAnyBut("zzabyycdxx", "")   = -1
2919     * StringUtils.indexOfAnyBut("aba", "ab")        = -1
2920     * </pre>
2921     *
2922     * @param seq  the CharSequence to check, may be null
2923     * @param searchChars  the chars to search for, may be null
2924     * @return the index of any of the chars, -1 if no match or null input
2925     * @since 2.0
2926     * @since 3.0 Changed signature from indexOfAnyBut(String, String) to indexOfAnyBut(CharSequence, CharSequence)
2927     */
2928    public static int indexOfAnyBut(final CharSequence seq, final CharSequence searchChars) {
2929        if (isEmpty(seq) || isEmpty(searchChars)) {
2930            return INDEX_NOT_FOUND;
2931        }
2932        final int strLen = seq.length();
2933        for (int i = 0; i < strLen; i++) {
2934            final char ch = seq.charAt(i);
2935            final boolean chFound = CharSequenceUtils.indexOf(searchChars, ch, 0) >= 0;
2936            if (i + 1 < strLen && Character.isHighSurrogate(ch)) {
2937                final char ch2 = seq.charAt(i + 1);
2938                if (chFound && CharSequenceUtils.indexOf(searchChars, ch2, 0) < 0) {
2939                    return i;
2940                }
2941            } else if (!chFound) {
2942                return i;
2943            }
2944        }
2945        return INDEX_NOT_FOUND;
2946    }
2947
2948    /**
2949     * Compares all CharSequences in an array and returns the index at which the
2950     * CharSequences begin to differ.
2951     *
2952     * <p>For example,
2953     * {@code indexOfDifference(new String[] {"i am a machine", "i am a robot"}) -> 7}</p>
2954     *
2955     * <pre>
2956     * StringUtils.indexOfDifference(null) = -1
2957     * StringUtils.indexOfDifference(new String[] {}) = -1
2958     * StringUtils.indexOfDifference(new String[] {"abc"}) = -1
2959     * StringUtils.indexOfDifference(new String[] {null, null}) = -1
2960     * StringUtils.indexOfDifference(new String[] {"", ""}) = -1
2961     * StringUtils.indexOfDifference(new String[] {"", null}) = 0
2962     * StringUtils.indexOfDifference(new String[] {"abc", null, null}) = 0
2963     * StringUtils.indexOfDifference(new String[] {null, null, "abc"}) = 0
2964     * StringUtils.indexOfDifference(new String[] {"", "abc"}) = 0
2965     * StringUtils.indexOfDifference(new String[] {"abc", ""}) = 0
2966     * StringUtils.indexOfDifference(new String[] {"abc", "abc"}) = -1
2967     * StringUtils.indexOfDifference(new String[] {"abc", "a"}) = 1
2968     * StringUtils.indexOfDifference(new String[] {"ab", "abxyz"}) = 2
2969     * StringUtils.indexOfDifference(new String[] {"abcde", "abxyz"}) = 2
2970     * StringUtils.indexOfDifference(new String[] {"abcde", "xyz"}) = 0
2971     * StringUtils.indexOfDifference(new String[] {"xyz", "abcde"}) = 0
2972     * StringUtils.indexOfDifference(new String[] {"i am a machine", "i am a robot"}) = 7
2973     * </pre>
2974     *
2975     * @param css  array of CharSequences, entries may be null
2976     * @return the index where the strings begin to differ; -1 if they are all equal
2977     * @since 2.4
2978     * @since 3.0 Changed signature from indexOfDifference(String...) to indexOfDifference(CharSequence...)
2979     */
2980    public static int indexOfDifference(final CharSequence... css) {
2981        if (ArrayUtils.getLength(css) <= 1) {
2982            return INDEX_NOT_FOUND;
2983        }
2984        boolean anyStringNull = false;
2985        boolean allStringsNull = true;
2986        final int arrayLen = css.length;
2987        int shortestStrLen = Integer.MAX_VALUE;
2988        int longestStrLen = 0;
2989
2990        // find the min and max string lengths; this avoids checking to make
2991        // sure we are not exceeding the length of the string each time through
2992        // the bottom loop.
2993        for (final CharSequence cs : css) {
2994            if (cs == null) {
2995                anyStringNull = true;
2996                shortestStrLen = 0;
2997            } else {
2998                allStringsNull = false;
2999                shortestStrLen = Math.min(cs.length(), shortestStrLen);
3000                longestStrLen = Math.max(cs.length(), longestStrLen);
3001            }
3002        }
3003
3004        // handle lists containing all nulls or all empty strings
3005        if (allStringsNull || longestStrLen == 0 && !anyStringNull) {
3006            return INDEX_NOT_FOUND;
3007        }
3008
3009        // handle lists containing some nulls or some empty strings
3010        if (shortestStrLen == 0) {
3011            return 0;
3012        }
3013
3014        // find the position with the first difference across all strings
3015        int firstDiff = -1;
3016        for (int stringPos = 0; stringPos < shortestStrLen; stringPos++) {
3017            final char comparisonChar = css[0].charAt(stringPos);
3018            for (int arrayPos = 1; arrayPos < arrayLen; arrayPos++) {
3019                if (css[arrayPos].charAt(stringPos) != comparisonChar) {
3020                    firstDiff = stringPos;
3021                    break;
3022                }
3023            }
3024            if (firstDiff != -1) {
3025                break;
3026            }
3027        }
3028
3029        if (firstDiff == -1 && shortestStrLen != longestStrLen) {
3030            // we compared all of the characters up to the length of the
3031            // shortest string and didn't find a match, but the string lengths
3032            // vary, so return the length of the shortest string.
3033            return shortestStrLen;
3034        }
3035        return firstDiff;
3036    }
3037
3038    /**
3039     * Compares two CharSequences, and returns the index at which the
3040     * CharSequences begin to differ.
3041     *
3042     * <p>For example,
3043     * {@code indexOfDifference("i am a machine", "i am a robot") -> 7}</p>
3044     *
3045     * <pre>
3046     * StringUtils.indexOfDifference(null, null) = -1
3047     * StringUtils.indexOfDifference("", "") = -1
3048     * StringUtils.indexOfDifference("", "abc") = 0
3049     * StringUtils.indexOfDifference("abc", "") = 0
3050     * StringUtils.indexOfDifference("abc", "abc") = -1
3051     * StringUtils.indexOfDifference("ab", "abxyz") = 2
3052     * StringUtils.indexOfDifference("abcde", "abxyz") = 2
3053     * StringUtils.indexOfDifference("abcde", "xyz") = 0
3054     * </pre>
3055     *
3056     * @param cs1  the first CharSequence, may be null
3057     * @param cs2  the second CharSequence, may be null
3058     * @return the index where cs1 and cs2 begin to differ; -1 if they are equal
3059     * @since 2.0
3060     * @since 3.0 Changed signature from indexOfDifference(String, String) to
3061     * indexOfDifference(CharSequence, CharSequence)
3062     */
3063    public static int indexOfDifference(final CharSequence cs1, final CharSequence cs2) {
3064        if (cs1 == cs2) {
3065            return INDEX_NOT_FOUND;
3066        }
3067        if (cs1 == null || cs2 == null) {
3068            return 0;
3069        }
3070        int i;
3071        for (i = 0; i < cs1.length() && i < cs2.length(); ++i) {
3072            if (cs1.charAt(i) != cs2.charAt(i)) {
3073                break;
3074            }
3075        }
3076        if (i < cs2.length() || i < cs1.length()) {
3077            return i;
3078        }
3079        return INDEX_NOT_FOUND;
3080    }
3081
3082    /**
3083     * Case in-sensitive find of the first index within a CharSequence.
3084     *
3085     * <p>A {@code null} CharSequence will return {@code -1}.
3086     * A negative start position is treated as zero.
3087     * An empty ("") search CharSequence always matches.
3088     * A start position greater than the string length only matches
3089     * an empty search CharSequence.</p>
3090     *
3091     * <pre>
3092     * StringUtils.indexOfIgnoreCase(null, *)          = -1
3093     * StringUtils.indexOfIgnoreCase(*, null)          = -1
3094     * StringUtils.indexOfIgnoreCase("", "")           = 0
3095     * StringUtils.indexOfIgnoreCase(" ", " ")         = 0
3096     * StringUtils.indexOfIgnoreCase("aabaabaa", "a")  = 0
3097     * StringUtils.indexOfIgnoreCase("aabaabaa", "b")  = 2
3098     * StringUtils.indexOfIgnoreCase("aabaabaa", "ab") = 1
3099     * </pre>
3100     *
3101     * @param str  the CharSequence to check, may be null
3102     * @param searchStr  the CharSequence to find, may be null
3103     * @return the first index of the search CharSequence,
3104     *  -1 if no match or {@code null} string input
3105     * @since 2.5
3106     * @since 3.0 Changed signature from indexOfIgnoreCase(String, String) to indexOfIgnoreCase(CharSequence, CharSequence)
3107     */
3108    public static int indexOfIgnoreCase(final CharSequence str, final CharSequence searchStr) {
3109        return indexOfIgnoreCase(str, searchStr, 0);
3110    }
3111
3112    /**
3113     * Case in-sensitive find of the first index within a CharSequence
3114     * from the specified position.
3115     *
3116     * <p>A {@code null} CharSequence will return {@code -1}.
3117     * A negative start position is treated as zero.
3118     * An empty ("") search CharSequence always matches.
3119     * A start position greater than the string length only matches
3120     * an empty search CharSequence.</p>
3121     *
3122     * <pre>
3123     * StringUtils.indexOfIgnoreCase(null, *, *)          = -1
3124     * StringUtils.indexOfIgnoreCase(*, null, *)          = -1
3125     * StringUtils.indexOfIgnoreCase("", "", 0)           = 0
3126     * StringUtils.indexOfIgnoreCase("aabaabaa", "A", 0)  = 0
3127     * StringUtils.indexOfIgnoreCase("aabaabaa", "B", 0)  = 2
3128     * StringUtils.indexOfIgnoreCase("aabaabaa", "AB", 0) = 1
3129     * StringUtils.indexOfIgnoreCase("aabaabaa", "B", 3)  = 5
3130     * StringUtils.indexOfIgnoreCase("aabaabaa", "B", 9)  = -1
3131     * StringUtils.indexOfIgnoreCase("aabaabaa", "B", -1) = 2
3132     * StringUtils.indexOfIgnoreCase("aabaabaa", "", 2)   = 2
3133     * StringUtils.indexOfIgnoreCase("abc", "", 9)        = -1
3134     * </pre>
3135     *
3136     * @param str  the CharSequence to check, may be null
3137     * @param searchStr  the CharSequence to find, may be null
3138     * @param startPos  the start position, negative treated as zero
3139     * @return the first index of the search CharSequence (always &ge; startPos),
3140     *  -1 if no match or {@code null} string input
3141     * @since 2.5
3142     * @since 3.0 Changed signature from indexOfIgnoreCase(String, String, int) to indexOfIgnoreCase(CharSequence, CharSequence, int)
3143     */
3144    public static int indexOfIgnoreCase(final CharSequence str, final CharSequence searchStr, int startPos) {
3145        if (str == null || searchStr == null) {
3146            return INDEX_NOT_FOUND;
3147        }
3148        if (startPos < 0) {
3149            startPos = 0;
3150        }
3151        final int endLimit = str.length() - searchStr.length() + 1;
3152        if (startPos > endLimit) {
3153            return INDEX_NOT_FOUND;
3154        }
3155        if (searchStr.length() == 0) {
3156            return startPos;
3157        }
3158        for (int i = startPos; i < endLimit; i++) {
3159            if (CharSequenceUtils.regionMatches(str, true, i, searchStr, 0, searchStr.length())) {
3160                return i;
3161            }
3162        }
3163        return INDEX_NOT_FOUND;
3164    }
3165
3166    /**
3167     * Checks if all of the CharSequences are empty (""), null or whitespace only.
3168     *
3169     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
3170     *
3171     * <pre>
3172     * StringUtils.isAllBlank(null)             = true
3173     * StringUtils.isAllBlank(null, "foo")      = false
3174     * StringUtils.isAllBlank(null, null)       = true
3175     * StringUtils.isAllBlank("", "bar")        = false
3176     * StringUtils.isAllBlank("bob", "")        = false
3177     * StringUtils.isAllBlank("  bob  ", null)  = false
3178     * StringUtils.isAllBlank(" ", "bar")       = false
3179     * StringUtils.isAllBlank("foo", "bar")     = false
3180     * StringUtils.isAllBlank(new String[] {})  = true
3181     * </pre>
3182     *
3183     * @param css  the CharSequences to check, may be null or empty
3184     * @return {@code true} if all of the CharSequences are empty or null or whitespace only
3185     * @since 3.6
3186     */
3187    public static boolean isAllBlank(final CharSequence... css) {
3188        if (ArrayUtils.isEmpty(css)) {
3189            return true;
3190        }
3191        for (final CharSequence cs : css) {
3192            if (isNotBlank(cs)) {
3193               return false;
3194            }
3195        }
3196        return true;
3197    }
3198
3199    /**
3200     * Checks if all of the CharSequences are empty ("") or null.
3201     *
3202     * <pre>
3203     * StringUtils.isAllEmpty(null)             = true
3204     * StringUtils.isAllEmpty(null, "")         = true
3205     * StringUtils.isAllEmpty(new String[] {})  = true
3206     * StringUtils.isAllEmpty(null, "foo")      = false
3207     * StringUtils.isAllEmpty("", "bar")        = false
3208     * StringUtils.isAllEmpty("bob", "")        = false
3209     * StringUtils.isAllEmpty("  bob  ", null)  = false
3210     * StringUtils.isAllEmpty(" ", "bar")       = false
3211     * StringUtils.isAllEmpty("foo", "bar")     = false
3212     * </pre>
3213     *
3214     * @param css  the CharSequences to check, may be null or empty
3215     * @return {@code true} if all of the CharSequences are empty or null
3216     * @since 3.6
3217     */
3218    public static boolean isAllEmpty(final CharSequence... css) {
3219        if (ArrayUtils.isEmpty(css)) {
3220            return true;
3221        }
3222        for (final CharSequence cs : css) {
3223            if (isNotEmpty(cs)) {
3224                return false;
3225            }
3226        }
3227        return true;
3228    }
3229
3230    /**
3231     * Checks if the CharSequence contains only lowercase characters.
3232     *
3233     * <p>{@code null} will return {@code false}.
3234     * An empty CharSequence (length()=0) will return {@code false}.</p>
3235     *
3236     * <pre>
3237     * StringUtils.isAllLowerCase(null)   = false
3238     * StringUtils.isAllLowerCase("")     = false
3239     * StringUtils.isAllLowerCase("  ")   = false
3240     * StringUtils.isAllLowerCase("abc")  = true
3241     * StringUtils.isAllLowerCase("abC")  = false
3242     * StringUtils.isAllLowerCase("ab c") = false
3243     * StringUtils.isAllLowerCase("ab1c") = false
3244     * StringUtils.isAllLowerCase("ab/c") = false
3245     * </pre>
3246     *
3247     * @param cs  the CharSequence to check, may be null
3248     * @return {@code true} if only contains lowercase characters, and is non-null
3249     * @since 2.5
3250     * @since 3.0 Changed signature from isAllLowerCase(String) to isAllLowerCase(CharSequence)
3251     */
3252    public static boolean isAllLowerCase(final CharSequence cs) {
3253        if (isEmpty(cs)) {
3254            return false;
3255        }
3256        final int sz = cs.length();
3257        for (int i = 0; i < sz; i++) {
3258            if (!Character.isLowerCase(cs.charAt(i))) {
3259                return false;
3260            }
3261        }
3262        return true;
3263    }
3264
3265    /**
3266     * Checks if the CharSequence contains only uppercase characters.
3267     *
3268     * <p>{@code null} will return {@code false}.
3269     * An empty String (length()=0) will return {@code false}.</p>
3270     *
3271     * <pre>
3272     * StringUtils.isAllUpperCase(null)   = false
3273     * StringUtils.isAllUpperCase("")     = false
3274     * StringUtils.isAllUpperCase("  ")   = false
3275     * StringUtils.isAllUpperCase("ABC")  = true
3276     * StringUtils.isAllUpperCase("aBC")  = false
3277     * StringUtils.isAllUpperCase("A C")  = false
3278     * StringUtils.isAllUpperCase("A1C")  = false
3279     * StringUtils.isAllUpperCase("A/C")  = false
3280     * </pre>
3281     *
3282     * @param cs the CharSequence to check, may be null
3283     * @return {@code true} if only contains uppercase characters, and is non-null
3284     * @since 2.5
3285     * @since 3.0 Changed signature from isAllUpperCase(String) to isAllUpperCase(CharSequence)
3286     */
3287    public static boolean isAllUpperCase(final CharSequence cs) {
3288        if (isEmpty(cs)) {
3289            return false;
3290        }
3291        final int sz = cs.length();
3292        for (int i = 0; i < sz; i++) {
3293            if (!Character.isUpperCase(cs.charAt(i))) {
3294                return false;
3295            }
3296        }
3297        return true;
3298    }
3299
3300    /**
3301     * Checks if the CharSequence contains only Unicode letters.
3302     *
3303     * <p>{@code null} will return {@code false}.
3304     * An empty CharSequence (length()=0) will return {@code false}.</p>
3305     *
3306     * <pre>
3307     * StringUtils.isAlpha(null)   = false
3308     * StringUtils.isAlpha("")     = false
3309     * StringUtils.isAlpha("  ")   = false
3310     * StringUtils.isAlpha("abc")  = true
3311     * StringUtils.isAlpha("ab2c") = false
3312     * StringUtils.isAlpha("ab-c") = false
3313     * </pre>
3314     *
3315     * @param cs  the CharSequence to check, may be null
3316     * @return {@code true} if only contains letters, and is non-null
3317     * @since 3.0 Changed signature from isAlpha(String) to isAlpha(CharSequence)
3318     * @since 3.0 Changed "" to return false and not true
3319     */
3320    public static boolean isAlpha(final CharSequence cs) {
3321        if (isEmpty(cs)) {
3322            return false;
3323        }
3324        final int sz = cs.length();
3325        for (int i = 0; i < sz; i++) {
3326            if (!Character.isLetter(cs.charAt(i))) {
3327                return false;
3328            }
3329        }
3330        return true;
3331    }
3332
3333    /**
3334     * Checks if the CharSequence contains only Unicode letters or digits.
3335     *
3336     * <p>{@code null} will return {@code false}.
3337     * An empty CharSequence (length()=0) will return {@code false}.</p>
3338     *
3339     * <pre>
3340     * StringUtils.isAlphanumeric(null)   = false
3341     * StringUtils.isAlphanumeric("")     = false
3342     * StringUtils.isAlphanumeric("  ")   = false
3343     * StringUtils.isAlphanumeric("abc")  = true
3344     * StringUtils.isAlphanumeric("ab c") = false
3345     * StringUtils.isAlphanumeric("ab2c") = true
3346     * StringUtils.isAlphanumeric("ab-c") = false
3347     * </pre>
3348     *
3349     * @param cs  the CharSequence to check, may be null
3350     * @return {@code true} if only contains letters or digits,
3351     *  and is non-null
3352     * @since 3.0 Changed signature from isAlphanumeric(String) to isAlphanumeric(CharSequence)
3353     * @since 3.0 Changed "" to return false and not true
3354     */
3355    public static boolean isAlphanumeric(final CharSequence cs) {
3356        if (isEmpty(cs)) {
3357            return false;
3358        }
3359        final int sz = cs.length();
3360        for (int i = 0; i < sz; i++) {
3361            if (!Character.isLetterOrDigit(cs.charAt(i))) {
3362                return false;
3363            }
3364        }
3365        return true;
3366    }
3367
3368    /**
3369     * Checks if the CharSequence contains only Unicode letters, digits
3370     * or space ({@code ' '}).
3371     *
3372     * <p>{@code null} will return {@code false}.
3373     * An empty CharSequence (length()=0) will return {@code true}.</p>
3374     *
3375     * <pre>
3376     * StringUtils.isAlphanumericSpace(null)   = false
3377     * StringUtils.isAlphanumericSpace("")     = true
3378     * StringUtils.isAlphanumericSpace("  ")   = true
3379     * StringUtils.isAlphanumericSpace("abc")  = true
3380     * StringUtils.isAlphanumericSpace("ab c") = true
3381     * StringUtils.isAlphanumericSpace("ab2c") = true
3382     * StringUtils.isAlphanumericSpace("ab-c") = false
3383     * </pre>
3384     *
3385     * @param cs  the CharSequence to check, may be null
3386     * @return {@code true} if only contains letters, digits or space,
3387     *  and is non-null
3388     * @since 3.0 Changed signature from isAlphanumericSpace(String) to isAlphanumericSpace(CharSequence)
3389     */
3390    public static boolean isAlphanumericSpace(final CharSequence cs) {
3391        if (cs == null) {
3392            return false;
3393        }
3394        final int sz = cs.length();
3395        for (int i = 0; i < sz; i++) {
3396            final char nowChar = cs.charAt(i);
3397            if (nowChar != ' ' && !Character.isLetterOrDigit(nowChar) ) {
3398                return false;
3399            }
3400        }
3401        return true;
3402    }
3403
3404    /**
3405     * Checks if the CharSequence contains only Unicode letters and
3406     * space (' ').
3407     *
3408     * <p>{@code null} will return {@code false}
3409     * An empty CharSequence (length()=0) will return {@code true}.</p>
3410     *
3411     * <pre>
3412     * StringUtils.isAlphaSpace(null)   = false
3413     * StringUtils.isAlphaSpace("")     = true
3414     * StringUtils.isAlphaSpace("  ")   = true
3415     * StringUtils.isAlphaSpace("abc")  = true
3416     * StringUtils.isAlphaSpace("ab c") = true
3417     * StringUtils.isAlphaSpace("ab2c") = false
3418     * StringUtils.isAlphaSpace("ab-c") = false
3419     * </pre>
3420     *
3421     * @param cs  the CharSequence to check, may be null
3422     * @return {@code true} if only contains letters and space,
3423     *  and is non-null
3424     * @since 3.0 Changed signature from isAlphaSpace(String) to isAlphaSpace(CharSequence)
3425     */
3426    public static boolean isAlphaSpace(final CharSequence cs) {
3427        if (cs == null) {
3428            return false;
3429        }
3430        final int sz = cs.length();
3431        for (int i = 0; i < sz; i++) {
3432            final char nowChar = cs.charAt(i);
3433            if (nowChar != ' ' && !Character.isLetter(nowChar)) {
3434                return false;
3435            }
3436        }
3437        return true;
3438    }
3439
3440    /**
3441     * Checks if any of the CharSequences are empty ("") or null or whitespace only.
3442     *
3443     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
3444     *
3445     * <pre>
3446     * StringUtils.isAnyBlank((String) null)    = true
3447     * StringUtils.isAnyBlank((String[]) null)  = false
3448     * StringUtils.isAnyBlank(null, "foo")      = true
3449     * StringUtils.isAnyBlank(null, null)       = true
3450     * StringUtils.isAnyBlank("", "bar")        = true
3451     * StringUtils.isAnyBlank("bob", "")        = true
3452     * StringUtils.isAnyBlank("  bob  ", null)  = true
3453     * StringUtils.isAnyBlank(" ", "bar")       = true
3454     * StringUtils.isAnyBlank(new String[] {})  = false
3455     * StringUtils.isAnyBlank(new String[]{""}) = true
3456     * StringUtils.isAnyBlank("foo", "bar")     = false
3457     * </pre>
3458     *
3459     * @param css  the CharSequences to check, may be null or empty
3460     * @return {@code true} if any of the CharSequences are empty or null or whitespace only
3461     * @since 3.2
3462     */
3463    public static boolean isAnyBlank(final CharSequence... css) {
3464        if (ArrayUtils.isEmpty(css)) {
3465            return false;
3466        }
3467        for (final CharSequence cs : css) {
3468            if (isBlank(cs)) {
3469                return true;
3470            }
3471        }
3472        return false;
3473    }
3474
3475    /**
3476     * Checks if any of the CharSequences are empty ("") or null.
3477     *
3478     * <pre>
3479     * StringUtils.isAnyEmpty((String) null)    = true
3480     * StringUtils.isAnyEmpty((String[]) null)  = false
3481     * StringUtils.isAnyEmpty(null, "foo")      = true
3482     * StringUtils.isAnyEmpty("", "bar")        = true
3483     * StringUtils.isAnyEmpty("bob", "")        = true
3484     * StringUtils.isAnyEmpty("  bob  ", null)  = true
3485     * StringUtils.isAnyEmpty(" ", "bar")       = false
3486     * StringUtils.isAnyEmpty("foo", "bar")     = false
3487     * StringUtils.isAnyEmpty(new String[]{})   = false
3488     * StringUtils.isAnyEmpty(new String[]{""}) = true
3489     * </pre>
3490     *
3491     * @param css  the CharSequences to check, may be null or empty
3492     * @return {@code true} if any of the CharSequences are empty or null
3493     * @since 3.2
3494     */
3495    public static boolean isAnyEmpty(final CharSequence... css) {
3496        if (ArrayUtils.isEmpty(css)) {
3497            return false;
3498        }
3499        for (final CharSequence cs : css) {
3500            if (isEmpty(cs)) {
3501                return true;
3502            }
3503        }
3504        return false;
3505    }
3506
3507    /**
3508     * Checks if the CharSequence contains only ASCII printable characters.
3509     *
3510     * <p>{@code null} will return {@code false}.
3511     * An empty CharSequence (length()=0) will return {@code true}.</p>
3512     *
3513     * <pre>
3514     * StringUtils.isAsciiPrintable(null)     = false
3515     * StringUtils.isAsciiPrintable("")       = true
3516     * StringUtils.isAsciiPrintable(" ")      = true
3517     * StringUtils.isAsciiPrintable("Ceki")   = true
3518     * StringUtils.isAsciiPrintable("ab2c")   = true
3519     * StringUtils.isAsciiPrintable("!ab-c~") = true
3520     * StringUtils.isAsciiPrintable("\u0020") = true
3521     * StringUtils.isAsciiPrintable("\u0021") = true
3522     * StringUtils.isAsciiPrintable("\u007e") = true
3523     * StringUtils.isAsciiPrintable("\u007f") = false
3524     * StringUtils.isAsciiPrintable("Ceki G\u00fclc\u00fc") = false
3525     * </pre>
3526     *
3527     * @param cs the CharSequence to check, may be null
3528     * @return {@code true} if every character is in the range
3529     *  32 through 126
3530     * @since 2.1
3531     * @since 3.0 Changed signature from isAsciiPrintable(String) to isAsciiPrintable(CharSequence)
3532     */
3533    public static boolean isAsciiPrintable(final CharSequence cs) {
3534        if (cs == null) {
3535            return false;
3536        }
3537        final int sz = cs.length();
3538        for (int i = 0; i < sz; i++) {
3539            if (!CharUtils.isAsciiPrintable(cs.charAt(i))) {
3540                return false;
3541            }
3542        }
3543        return true;
3544    }
3545
3546    /**
3547     * Checks if a CharSequence is empty (""), null or whitespace only.
3548     *
3549     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
3550     *
3551     * <pre>
3552     * StringUtils.isBlank(null)      = true
3553     * StringUtils.isBlank("")        = true
3554     * StringUtils.isBlank(" ")       = true
3555     * StringUtils.isBlank("bob")     = false
3556     * StringUtils.isBlank("  bob  ") = false
3557     * </pre>
3558     *
3559     * @param cs  the CharSequence to check, may be null
3560     * @return {@code true} if the CharSequence is null, empty or whitespace only
3561     * @since 2.0
3562     * @since 3.0 Changed signature from isBlank(String) to isBlank(CharSequence)
3563     */
3564    public static boolean isBlank(final CharSequence cs) {
3565        final int strLen = length(cs);
3566        if (strLen == 0) {
3567            return true;
3568        }
3569        for (int i = 0; i < strLen; i++) {
3570            if (!Character.isWhitespace(cs.charAt(i))) {
3571                return false;
3572            }
3573        }
3574        return true;
3575    }
3576
3577    /**
3578     * Checks if a CharSequence is empty ("") or null.
3579     *
3580     * <pre>
3581     * StringUtils.isEmpty(null)      = true
3582     * StringUtils.isEmpty("")        = true
3583     * StringUtils.isEmpty(" ")       = false
3584     * StringUtils.isEmpty("bob")     = false
3585     * StringUtils.isEmpty("  bob  ") = false
3586     * </pre>
3587     *
3588     * <p>NOTE: This method changed in Lang version 2.0.
3589     * It no longer trims the CharSequence.
3590     * That functionality is available in isBlank().</p>
3591     *
3592     * @param cs  the CharSequence to check, may be null
3593     * @return {@code true} if the CharSequence is empty or null
3594     * @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)
3595     */
3596    public static boolean isEmpty(final CharSequence cs) {
3597        return cs == null || cs.length() == 0;
3598    }
3599
3600    /**
3601     * Checks if the CharSequence contains mixed casing of both uppercase and lowercase characters.
3602     *
3603     * <p>{@code null} will return {@code false}. An empty CharSequence ({@code length()=0}) will return
3604     * {@code false}.</p>
3605     *
3606     * <pre>
3607     * StringUtils.isMixedCase(null)    = false
3608     * StringUtils.isMixedCase("")      = false
3609     * StringUtils.isMixedCase(" ")     = false
3610     * StringUtils.isMixedCase("ABC")   = false
3611     * StringUtils.isMixedCase("abc")   = false
3612     * StringUtils.isMixedCase("aBc")   = true
3613     * StringUtils.isMixedCase("A c")   = true
3614     * StringUtils.isMixedCase("A1c")   = true
3615     * StringUtils.isMixedCase("a/C")   = true
3616     * StringUtils.isMixedCase("aC\t")  = true
3617     * </pre>
3618     *
3619     * @param cs the CharSequence to check, may be null
3620     * @return {@code true} if the CharSequence contains both uppercase and lowercase characters
3621     * @since 3.5
3622     */
3623    public static boolean isMixedCase(final CharSequence cs) {
3624        if (isEmpty(cs) || cs.length() == 1) {
3625            return false;
3626        }
3627        boolean containsUppercase = false;
3628        boolean containsLowercase = false;
3629        final int sz = cs.length();
3630        for (int i = 0; i < sz; i++) {
3631            if (containsUppercase && containsLowercase) {
3632                return true;
3633            }
3634            if (Character.isUpperCase(cs.charAt(i))) {
3635                containsUppercase = true;
3636            } else if (Character.isLowerCase(cs.charAt(i))) {
3637                containsLowercase = true;
3638            }
3639        }
3640        return containsUppercase && containsLowercase;
3641    }
3642
3643    /**
3644     * Checks if none of the CharSequences are empty (""), null or whitespace only.
3645     *
3646     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
3647     *
3648     * <pre>
3649     * StringUtils.isNoneBlank((String) null)    = false
3650     * StringUtils.isNoneBlank((String[]) null)  = true
3651     * StringUtils.isNoneBlank(null, "foo")      = false
3652     * StringUtils.isNoneBlank(null, null)       = false
3653     * StringUtils.isNoneBlank("", "bar")        = false
3654     * StringUtils.isNoneBlank("bob", "")        = false
3655     * StringUtils.isNoneBlank("  bob  ", null)  = false
3656     * StringUtils.isNoneBlank(" ", "bar")       = false
3657     * StringUtils.isNoneBlank(new String[] {})  = true
3658     * StringUtils.isNoneBlank(new String[]{""}) = false
3659     * StringUtils.isNoneBlank("foo", "bar")     = true
3660     * </pre>
3661     *
3662     * @param css  the CharSequences to check, may be null or empty
3663     * @return {@code true} if none of the CharSequences are empty or null or whitespace only
3664     * @since 3.2
3665     */
3666    public static boolean isNoneBlank(final CharSequence... css) {
3667      return !isAnyBlank(css);
3668    }
3669
3670    /**
3671     * Checks if none of the CharSequences are empty ("") or null.
3672     *
3673     * <pre>
3674     * StringUtils.isNoneEmpty((String) null)    = false
3675     * StringUtils.isNoneEmpty((String[]) null)  = true
3676     * StringUtils.isNoneEmpty(null, "foo")      = false
3677     * StringUtils.isNoneEmpty("", "bar")        = false
3678     * StringUtils.isNoneEmpty("bob", "")        = false
3679     * StringUtils.isNoneEmpty("  bob  ", null)  = false
3680     * StringUtils.isNoneEmpty(new String[] {})  = true
3681     * StringUtils.isNoneEmpty(new String[]{""}) = false
3682     * StringUtils.isNoneEmpty(" ", "bar")       = true
3683     * StringUtils.isNoneEmpty("foo", "bar")     = true
3684     * </pre>
3685     *
3686     * @param css  the CharSequences to check, may be null or empty
3687     * @return {@code true} if none of the CharSequences are empty or null
3688     * @since 3.2
3689     */
3690    public static boolean isNoneEmpty(final CharSequence... css) {
3691      return !isAnyEmpty(css);
3692    }
3693
3694    /**
3695     * Checks if a CharSequence is not empty (""), not null and not whitespace only.
3696     *
3697     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
3698     *
3699     * <pre>
3700     * StringUtils.isNotBlank(null)      = false
3701     * StringUtils.isNotBlank("")        = false
3702     * StringUtils.isNotBlank(" ")       = false
3703     * StringUtils.isNotBlank("bob")     = true
3704     * StringUtils.isNotBlank("  bob  ") = true
3705     * </pre>
3706     *
3707     * @param cs  the CharSequence to check, may be null
3708     * @return {@code true} if the CharSequence is
3709     *  not empty and not null and not whitespace only
3710     * @since 2.0
3711     * @since 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence)
3712     */
3713    public static boolean isNotBlank(final CharSequence cs) {
3714        return !isBlank(cs);
3715    }
3716
3717    /**
3718     * Checks if a CharSequence is not empty ("") and not null.
3719     *
3720     * <pre>
3721     * StringUtils.isNotEmpty(null)      = false
3722     * StringUtils.isNotEmpty("")        = false
3723     * StringUtils.isNotEmpty(" ")       = true
3724     * StringUtils.isNotEmpty("bob")     = true
3725     * StringUtils.isNotEmpty("  bob  ") = true
3726     * </pre>
3727     *
3728     * @param cs  the CharSequence to check, may be null
3729     * @return {@code true} if the CharSequence is not empty and not null
3730     * @since 3.0 Changed signature from isNotEmpty(String) to isNotEmpty(CharSequence)
3731     */
3732    public static boolean isNotEmpty(final CharSequence cs) {
3733        return !isEmpty(cs);
3734    }
3735
3736    /**
3737     * Checks if the CharSequence contains only Unicode digits.
3738     * A decimal point is not a Unicode digit and returns false.
3739     *
3740     * <p>{@code null} will return {@code false}.
3741     * An empty CharSequence (length()=0) will return {@code false}.</p>
3742     *
3743     * <p>Note that the method does not allow for a leading sign, either positive or negative.
3744     * Also, if a String passes the numeric test, it may still generate a NumberFormatException
3745     * when parsed by Integer.parseInt or Long.parseLong, e.g. if the value is outside the range
3746     * for int or long respectively.</p>
3747     *
3748     * <pre>
3749     * StringUtils.isNumeric(null)   = false
3750     * StringUtils.isNumeric("")     = false
3751     * StringUtils.isNumeric("  ")   = false
3752     * StringUtils.isNumeric("123")  = true
3753     * StringUtils.isNumeric("\u0967\u0968\u0969")  = true
3754     * StringUtils.isNumeric("12 3") = false
3755     * StringUtils.isNumeric("ab2c") = false
3756     * StringUtils.isNumeric("12-3") = false
3757     * StringUtils.isNumeric("12.3") = false
3758     * StringUtils.isNumeric("-123") = false
3759     * StringUtils.isNumeric("+123") = false
3760     * </pre>
3761     *
3762     * @param cs  the CharSequence to check, may be null
3763     * @return {@code true} if only contains digits, and is non-null
3764     * @since 3.0 Changed signature from isNumeric(String) to isNumeric(CharSequence)
3765     * @since 3.0 Changed "" to return false and not true
3766     */
3767    public static boolean isNumeric(final CharSequence cs) {
3768        if (isEmpty(cs)) {
3769            return false;
3770        }
3771        final int sz = cs.length();
3772        for (int i = 0; i < sz; i++) {
3773            if (!Character.isDigit(cs.charAt(i))) {
3774                return false;
3775            }
3776        }
3777        return true;
3778    }
3779
3780    /**
3781     * Checks if the CharSequence contains only Unicode digits or space
3782     * ({@code ' '}).
3783     * A decimal point is not a Unicode digit and returns false.
3784     *
3785     * <p>{@code null} will return {@code false}.
3786     * An empty CharSequence (length()=0) will return {@code true}.</p>
3787     *
3788     * <pre>
3789     * StringUtils.isNumericSpace(null)   = false
3790     * StringUtils.isNumericSpace("")     = true
3791     * StringUtils.isNumericSpace("  ")   = true
3792     * StringUtils.isNumericSpace("123")  = true
3793     * StringUtils.isNumericSpace("12 3") = true
3794     * StringUtils.isNumericSpace("\u0967\u0968\u0969")  = true
3795     * StringUtils.isNumericSpace("\u0967\u0968 \u0969")  = true
3796     * StringUtils.isNumericSpace("ab2c") = false
3797     * StringUtils.isNumericSpace("12-3") = false
3798     * StringUtils.isNumericSpace("12.3") = false
3799     * </pre>
3800     *
3801     * @param cs  the CharSequence to check, may be null
3802     * @return {@code true} if only contains digits or space,
3803     *  and is non-null
3804     * @since 3.0 Changed signature from isNumericSpace(String) to isNumericSpace(CharSequence)
3805     */
3806    public static boolean isNumericSpace(final CharSequence cs) {
3807        if (cs == null) {
3808            return false;
3809        }
3810        final int sz = cs.length();
3811        for (int i = 0; i < sz; i++) {
3812            final char nowChar = cs.charAt(i);
3813            if (nowChar != ' ' && !Character.isDigit(nowChar)) {
3814                return false;
3815            }
3816        }
3817        return true;
3818    }
3819
3820    /**
3821     * Checks if the CharSequence contains only whitespace.
3822     *
3823     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
3824     *
3825     * <p>{@code null} will return {@code false}.
3826     * An empty CharSequence (length()=0) will return {@code true}.</p>
3827     *
3828     * <pre>
3829     * StringUtils.isWhitespace(null)   = false
3830     * StringUtils.isWhitespace("")     = true
3831     * StringUtils.isWhitespace("  ")   = true
3832     * StringUtils.isWhitespace("abc")  = false
3833     * StringUtils.isWhitespace("ab2c") = false
3834     * StringUtils.isWhitespace("ab-c") = false
3835     * </pre>
3836     *
3837     * @param cs  the CharSequence to check, may be null
3838     * @return {@code true} if only contains whitespace, and is non-null
3839     * @since 2.0
3840     * @since 3.0 Changed signature from isWhitespace(String) to isWhitespace(CharSequence)
3841     */
3842    public static boolean isWhitespace(final CharSequence cs) {
3843        if (cs == null) {
3844            return false;
3845        }
3846        final int sz = cs.length();
3847        for (int i = 0; i < sz; i++) {
3848            if (!Character.isWhitespace(cs.charAt(i))) {
3849                return false;
3850            }
3851        }
3852        return true;
3853    }
3854
3855    /**
3856     * Joins the elements of the provided array into a single String containing the provided list of elements.
3857     *
3858     * <p>
3859     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
3860     * by empty strings.
3861     * </p>
3862     *
3863     * <pre>
3864     * StringUtils.join(null, *)              = null
3865     * StringUtils.join([], *)                = ""
3866     * StringUtils.join([null], *)            = ""
3867     * StringUtils.join([false, false], ';')  = "false;false"
3868     * </pre>
3869     *
3870     * @param array
3871     *            the array of values to join together, may be null
3872     * @param delimiter
3873     *            the separator character to use
3874     * @return the joined String, {@code null} if null array input
3875     * @since 3.12.0
3876     */
3877    public static String join(final boolean[] array, final char delimiter) {
3878        if (array == null) {
3879            return null;
3880        }
3881        return join(array, delimiter, 0, array.length);
3882    }
3883
3884    /**
3885     * Joins the elements of the provided array into a single String containing the provided list of elements.
3886     *
3887     * <p>
3888     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
3889     * by empty strings.
3890     * </p>
3891     *
3892     * <pre>
3893     * StringUtils.join(null, *)                   = null
3894     * StringUtils.join([], *)                     = ""
3895     * StringUtils.join([null], *)                 = ""
3896     * StringUtils.join([true, false, true], ';')  = "true;false;true"
3897     * </pre>
3898     *
3899     * @param array
3900     *            the array of values to join together, may be null
3901     * @param delimiter
3902     *            the separator character to use
3903     * @param startIndex
3904     *            the first index to start joining from. It is an error to pass in a start index past the end of the
3905     *            array
3906     * @param endIndex
3907     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
3908     *            the array
3909     * @return the joined String, {@code null} if null array input
3910     * @since 3.12.0
3911     */
3912    public static String join(final boolean[] array, final char delimiter, final int startIndex, final int endIndex) {
3913        if (array == null) {
3914            return null;
3915        }
3916        if (endIndex - startIndex <= 0) {
3917            return EMPTY;
3918        }
3919        final StringBuilder stringBuilder = new StringBuilder(array.length * 5 + array.length - 1);
3920        for (int i = startIndex; i < endIndex; i++) {
3921            stringBuilder
3922                    .append(array[i])
3923                    .append(delimiter);
3924        }
3925        return stringBuilder.substring(0, stringBuilder.length() - 1);
3926    }
3927
3928    /**
3929     * Joins the elements of the provided array into a single String containing the provided list of elements.
3930     *
3931     * <p>
3932     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
3933     * by empty strings.
3934     * </p>
3935     *
3936     * <pre>
3937     * StringUtils.join(null, *)               = null
3938     * StringUtils.join([], *)                 = ""
3939     * StringUtils.join([null], *)             = ""
3940     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
3941     * StringUtils.join([1, 2, 3], null) = "123"
3942     * </pre>
3943     *
3944     * @param array
3945     *            the array of values to join together, may be null
3946     * @param delimiter
3947     *            the separator character to use
3948     * @return the joined String, {@code null} if null array input
3949     * @since 3.2
3950     */
3951    public static String join(final byte[] array, final char delimiter) {
3952        if (array == null) {
3953            return null;
3954        }
3955        return join(array, delimiter, 0, array.length);
3956    }
3957
3958    /**
3959     * Joins the elements of the provided array into a single String containing the provided list of elements.
3960     *
3961     * <p>
3962     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
3963     * by empty strings.
3964     * </p>
3965     *
3966     * <pre>
3967     * StringUtils.join(null, *)               = null
3968     * StringUtils.join([], *)                 = ""
3969     * StringUtils.join([null], *)             = ""
3970     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
3971     * StringUtils.join([1, 2, 3], null) = "123"
3972     * </pre>
3973     *
3974     * @param array
3975     *            the array of values to join together, may be null
3976     * @param delimiter
3977     *            the separator character to use
3978     * @param startIndex
3979     *            the first index to start joining from. It is an error to pass in a start index past the end of the
3980     *            array
3981     * @param endIndex
3982     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
3983     *            the array
3984     * @return the joined String, {@code null} if null array input
3985     * @since 3.2
3986     */
3987    public static String join(final byte[] array, final char delimiter, final int startIndex, final int endIndex) {
3988        if (array == null) {
3989            return null;
3990        }
3991        if (endIndex - startIndex <= 0) {
3992            return EMPTY;
3993        }
3994        final StringBuilder stringBuilder = new StringBuilder();
3995        for (int i = startIndex; i < endIndex; i++) {
3996            stringBuilder
3997                    .append(array[i])
3998                    .append(delimiter);
3999        }
4000        return stringBuilder.substring(0, stringBuilder.length() - 1);
4001    }
4002
4003    /**
4004     * Joins the elements of the provided array into a single String containing the provided list of elements.
4005     *
4006     * <p>
4007     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4008     * by empty strings.
4009     * </p>
4010     *
4011     * <pre>
4012     * StringUtils.join(null, *)               = null
4013     * StringUtils.join([], *)                 = ""
4014     * StringUtils.join([null], *)             = ""
4015     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4016     * StringUtils.join([1, 2, 3], null) = "123"
4017     * </pre>
4018     *
4019     * @param array
4020     *            the array of values to join together, may be null
4021     * @param delimiter
4022     *            the separator character to use
4023     * @return the joined String, {@code null} if null array input
4024     * @since 3.2
4025     */
4026    public static String join(final char[] array, final char delimiter) {
4027        if (array == null) {
4028            return null;
4029        }
4030        return join(array, delimiter, 0, array.length);
4031    }
4032
4033    /**
4034     * Joins the elements of the provided array into a single String containing the provided list of elements.
4035     *
4036     * <p>
4037     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4038     * by empty strings.
4039     * </p>
4040     *
4041     * <pre>
4042     * StringUtils.join(null, *)               = null
4043     * StringUtils.join([], *)                 = ""
4044     * StringUtils.join([null], *)             = ""
4045     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4046     * StringUtils.join([1, 2, 3], null) = "123"
4047     * </pre>
4048     *
4049     * @param array
4050     *            the array of values to join together, may be null
4051     * @param delimiter
4052     *            the separator character to use
4053     * @param startIndex
4054     *            the first index to start joining from. It is an error to pass in a start index past the end of the
4055     *            array
4056     * @param endIndex
4057     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
4058     *            the array
4059     * @return the joined String, {@code null} if null array input
4060     * @since 3.2
4061     */
4062    public static String join(final char[] array, final char delimiter, final int startIndex, final int endIndex) {
4063        if (array == null) {
4064            return null;
4065        }
4066        if (endIndex - startIndex <= 0) {
4067            return EMPTY;
4068        }
4069        final StringBuilder stringBuilder = new StringBuilder(array.length * 2 - 1);
4070        for (int i = startIndex; i < endIndex; i++) {
4071            stringBuilder
4072                    .append(array[i])
4073                    .append(delimiter);
4074        }
4075        return stringBuilder.substring(0, stringBuilder.length() - 1);
4076    }
4077
4078    /**
4079     * Joins the elements of the provided array into a single String containing the provided list of elements.
4080     *
4081     * <p>
4082     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4083     * by empty strings.
4084     * </p>
4085     *
4086     * <pre>
4087     * StringUtils.join(null, *)               = null
4088     * StringUtils.join([], *)                 = ""
4089     * StringUtils.join([null], *)             = ""
4090     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4091     * StringUtils.join([1, 2, 3], null) = "123"
4092     * </pre>
4093     *
4094     * @param array
4095     *            the array of values to join together, may be null
4096     * @param delimiter
4097     *            the separator character to use
4098     * @return the joined String, {@code null} if null array input
4099     * @since 3.2
4100     */
4101    public static String join(final double[] array, final char delimiter) {
4102        if (array == null) {
4103            return null;
4104        }
4105        return join(array, delimiter, 0, array.length);
4106    }
4107
4108    /**
4109     * Joins the elements of the provided array into a single String containing the provided list of elements.
4110     *
4111     * <p>
4112     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4113     * by empty strings.
4114     * </p>
4115     *
4116     * <pre>
4117     * StringUtils.join(null, *)               = null
4118     * StringUtils.join([], *)                 = ""
4119     * StringUtils.join([null], *)             = ""
4120     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4121     * StringUtils.join([1, 2, 3], null) = "123"
4122     * </pre>
4123     *
4124     * @param array
4125     *            the array of values to join together, may be null
4126     * @param delimiter
4127     *            the separator character to use
4128     * @param startIndex
4129     *            the first index to start joining from. It is an error to pass in a start index past the end of the
4130     *            array
4131     * @param endIndex
4132     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
4133     *            the array
4134     * @return the joined String, {@code null} if null array input
4135     * @since 3.2
4136     */
4137    public static String join(final double[] array, final char delimiter, final int startIndex, final int endIndex) {
4138        if (array == null) {
4139            return null;
4140        }
4141        if (endIndex - startIndex <= 0) {
4142            return EMPTY;
4143        }
4144        final StringBuilder stringBuilder = new StringBuilder();
4145        for (int i = startIndex; i < endIndex; i++) {
4146            stringBuilder
4147                    .append(array[i])
4148                    .append(delimiter);
4149        }
4150        return stringBuilder.substring(0, stringBuilder.length() - 1);
4151    }
4152
4153    /**
4154     * Joins the elements of the provided array into a single String containing the provided list of elements.
4155     *
4156     * <p>
4157     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4158     * by empty strings.
4159     * </p>
4160     *
4161     * <pre>
4162     * StringUtils.join(null, *)               = null
4163     * StringUtils.join([], *)                 = ""
4164     * StringUtils.join([null], *)             = ""
4165     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4166     * StringUtils.join([1, 2, 3], null) = "123"
4167     * </pre>
4168     *
4169     * @param array
4170     *            the array of values to join together, may be null
4171     * @param delimiter
4172     *            the separator character to use
4173     * @return the joined String, {@code null} if null array input
4174     * @since 3.2
4175     */
4176    public static String join(final float[] array, final char delimiter) {
4177        if (array == null) {
4178            return null;
4179        }
4180        return join(array, delimiter, 0, array.length);
4181    }
4182
4183    /**
4184     * Joins the elements of the provided array into a single String containing the provided list of elements.
4185     *
4186     * <p>
4187     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4188     * by empty strings.
4189     * </p>
4190     *
4191     * <pre>
4192     * StringUtils.join(null, *)               = null
4193     * StringUtils.join([], *)                 = ""
4194     * StringUtils.join([null], *)             = ""
4195     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4196     * StringUtils.join([1, 2, 3], null) = "123"
4197     * </pre>
4198     *
4199     * @param array
4200     *            the array of values to join together, may be null
4201     * @param delimiter
4202     *            the separator character to use
4203     * @param startIndex
4204     *            the first index to start joining from. It is an error to pass in a start index past the end of the
4205     *            array
4206     * @param endIndex
4207     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
4208     *            the array
4209     * @return the joined String, {@code null} if null array input
4210     * @since 3.2
4211     */
4212    public static String join(final float[] array, final char delimiter, final int startIndex, final int endIndex) {
4213        if (array == null) {
4214            return null;
4215        }
4216        if (endIndex - startIndex <= 0) {
4217            return EMPTY;
4218        }
4219        final StringBuilder stringBuilder = new StringBuilder();
4220        for (int i = startIndex; i < endIndex; i++) {
4221            stringBuilder
4222                    .append(array[i])
4223                    .append(delimiter);
4224        }
4225        return stringBuilder.substring(0, stringBuilder.length() - 1);
4226    }
4227
4228    /**
4229     * Joins the elements of the provided array into a single String containing the provided list of elements.
4230     *
4231     * <p>
4232     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4233     * by empty strings.
4234     * </p>
4235     *
4236     * <pre>
4237     * StringUtils.join(null, *)               = null
4238     * StringUtils.join([], *)                 = ""
4239     * StringUtils.join([null], *)             = ""
4240     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4241     * StringUtils.join([1, 2, 3], null) = "123"
4242     * </pre>
4243     *
4244     * @param array
4245     *            the array of values to join together, may be null
4246     * @param separator
4247     *            the separator character to use
4248     * @return the joined String, {@code null} if null array input
4249     * @since 3.2
4250     */
4251    public static String join(final int[] array, final char separator) {
4252        if (array == null) {
4253            return null;
4254        }
4255        return join(array, separator, 0, array.length);
4256    }
4257
4258    /**
4259     * Joins the elements of the provided array into a single String containing the provided list of elements.
4260     *
4261     * <p>
4262     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4263     * by empty strings.
4264     * </p>
4265     *
4266     * <pre>
4267     * StringUtils.join(null, *)               = null
4268     * StringUtils.join([], *)                 = ""
4269     * StringUtils.join([null], *)             = ""
4270     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4271     * StringUtils.join([1, 2, 3], null) = "123"
4272     * </pre>
4273     *
4274     * @param array
4275     *            the array of values to join together, may be null
4276     * @param delimiter
4277     *            the separator character to use
4278     * @param startIndex
4279     *            the first index to start joining from. It is an error to pass in a start index past the end of the
4280     *            array
4281     * @param endIndex
4282     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
4283     *            the array
4284     * @return the joined String, {@code null} if null array input
4285     * @since 3.2
4286     */
4287    public static String join(final int[] array, final char delimiter, final int startIndex, final int endIndex) {
4288        if (array == null) {
4289            return null;
4290        }
4291        if (endIndex - startIndex <= 0) {
4292            return EMPTY;
4293        }
4294        final StringBuilder stringBuilder = new StringBuilder();
4295        for (int i = startIndex; i < endIndex; i++) {
4296            stringBuilder
4297                    .append(array[i])
4298                    .append(delimiter);
4299        }
4300        return stringBuilder.substring(0, stringBuilder.length() - 1);
4301    }
4302
4303    /**
4304     * Joins the elements of the provided {@link Iterable} into
4305     * a single String containing the provided elements.
4306     *
4307     * <p>No delimiter is added before or after the list. Null objects or empty
4308     * strings within the iteration are represented by empty strings.</p>
4309     *
4310     * <p>See the examples here: {@link #join(Object[],char)}.</p>
4311     *
4312     * @param iterable  the {@link Iterable} providing the values to join together, may be null
4313     * @param separator  the separator character to use
4314     * @return the joined String, {@code null} if null iterator input
4315     * @since 2.3
4316     */
4317    public static String join(final Iterable<?> iterable, final char separator) {
4318        return iterable != null ? join(iterable.iterator(), separator) : null;
4319    }
4320
4321    /**
4322     * Joins the elements of the provided {@link Iterable} into
4323     * a single String containing the provided elements.
4324     *
4325     * <p>No delimiter is added before or after the list.
4326     * A {@code null} separator is the same as an empty String ("").</p>
4327     *
4328     * <p>See the examples here: {@link #join(Object[],String)}.</p>
4329     *
4330     * @param iterable  the {@link Iterable} providing the values to join together, may be null
4331     * @param separator  the separator character to use, null treated as ""
4332     * @return the joined String, {@code null} if null iterator input
4333     * @since 2.3
4334     */
4335    public static String join(final Iterable<?> iterable, final String separator) {
4336        return iterable != null ? join(iterable.iterator(), separator) : null;
4337    }
4338
4339    /**
4340     * Joins the elements of the provided {@link Iterator} into
4341     * a single String containing the provided elements.
4342     *
4343     * <p>No delimiter is added before or after the list. Null objects or empty
4344     * strings within the iteration are represented by empty strings.</p>
4345     *
4346     * <p>See the examples here: {@link #join(Object[],char)}.</p>
4347     *
4348     * @param iterator  the {@link Iterator} of values to join together, may be null
4349     * @param separator  the separator character to use
4350     * @return the joined String, {@code null} if null iterator input
4351     * @since 2.0
4352     */
4353    public static String join(final Iterator<?> iterator, final char separator) {
4354        // handle null, zero and one elements before building a buffer
4355        if (iterator == null) {
4356            return null;
4357        }
4358        if (!iterator.hasNext()) {
4359            return EMPTY;
4360        }
4361        return Streams.of(iterator).collect(LangCollectors.joining(toStringOrEmpty(String.valueOf(separator)), EMPTY, EMPTY, StringUtils::toStringOrEmpty));
4362    }
4363
4364    /**
4365     * Joins the elements of the provided {@link Iterator} into
4366     * a single String containing the provided elements.
4367     *
4368     * <p>No delimiter is added before or after the list.
4369     * A {@code null} separator is the same as an empty String ("").</p>
4370     *
4371     * <p>See the examples here: {@link #join(Object[],String)}.</p>
4372     *
4373     * @param iterator  the {@link Iterator} of values to join together, may be null
4374     * @param separator  the separator character to use, null treated as ""
4375     * @return the joined String, {@code null} if null iterator input
4376     */
4377    public static String join(final Iterator<?> iterator, final String separator) {
4378        // handle null, zero and one elements before building a buffer
4379        if (iterator == null) {
4380            return null;
4381        }
4382        if (!iterator.hasNext()) {
4383            return EMPTY;
4384        }
4385        return Streams.of(iterator).collect(LangCollectors.joining(toStringOrEmpty(separator), EMPTY, EMPTY, StringUtils::toStringOrEmpty));
4386    }
4387
4388    /**
4389     * Joins the elements of the provided {@link List} into a single String
4390     * containing the provided list of elements.
4391     *
4392     * <p>No delimiter is added before or after the list.
4393     * Null objects or empty strings within the array are represented by
4394     * empty strings.</p>
4395     *
4396     * <pre>
4397     * StringUtils.join(null, *)               = null
4398     * StringUtils.join([], *)                 = ""
4399     * StringUtils.join([null], *)             = ""
4400     * StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
4401     * StringUtils.join(["a", "b", "c"], null) = "abc"
4402     * StringUtils.join([null, "", "a"], ';')  = ";;a"
4403     * </pre>
4404     *
4405     * @param list  the {@link List} of values to join together, may be null
4406     * @param separator  the separator character to use
4407     * @param startIndex the first index to start joining from.  It is
4408     * an error to pass in a start index past the end of the list
4409     * @param endIndex the index to stop joining from (exclusive). It is
4410     * an error to pass in an end index past the end of the list
4411     * @return the joined String, {@code null} if null list input
4412     * @since 3.8
4413     */
4414    public static String join(final List<?> list, final char separator, final int startIndex, final int endIndex) {
4415        if (list == null) {
4416            return null;
4417        }
4418        final int noOfItems = endIndex - startIndex;
4419        if (noOfItems <= 0) {
4420            return EMPTY;
4421        }
4422        final List<?> subList = list.subList(startIndex, endIndex);
4423        return join(subList.iterator(), separator);
4424    }
4425
4426    /**
4427     * Joins the elements of the provided {@link List} into a single String
4428     * containing the provided list of elements.
4429     *
4430     * <p>No delimiter is added before or after the list.
4431     * Null objects or empty strings within the array are represented by
4432     * empty strings.</p>
4433     *
4434     * <pre>
4435     * StringUtils.join(null, *)               = null
4436     * StringUtils.join([], *)                 = ""
4437     * StringUtils.join([null], *)             = ""
4438     * StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
4439     * StringUtils.join(["a", "b", "c"], null) = "abc"
4440     * StringUtils.join([null, "", "a"], ';')  = ";;a"
4441     * </pre>
4442     *
4443     * @param list  the {@link List} of values to join together, may be null
4444     * @param separator  the separator character to use
4445     * @param startIndex the first index to start joining from.  It is
4446     * an error to pass in a start index past the end of the list
4447     * @param endIndex the index to stop joining from (exclusive). It is
4448     * an error to pass in an end index past the end of the list
4449     * @return the joined String, {@code null} if null list input
4450     * @since 3.8
4451     */
4452    public static String join(final List<?> list, final String separator, final int startIndex, final int endIndex) {
4453        if (list == null) {
4454            return null;
4455        }
4456        final int noOfItems = endIndex - startIndex;
4457        if (noOfItems <= 0) {
4458            return EMPTY;
4459        }
4460        final List<?> subList = list.subList(startIndex, endIndex);
4461        return join(subList.iterator(), separator);
4462    }
4463
4464
4465    /**
4466     * Joins the elements of the provided array into a single String containing the provided list of elements.
4467     *
4468     * <p>
4469     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4470     * by empty strings.
4471     * </p>
4472     *
4473     * <pre>
4474     * StringUtils.join(null, *)               = null
4475     * StringUtils.join([], *)                 = ""
4476     * StringUtils.join([null], *)             = ""
4477     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4478     * StringUtils.join([1, 2, 3], null) = "123"
4479     * </pre>
4480     *
4481     * @param array
4482     *            the array of values to join together, may be null
4483     * @param separator
4484     *            the separator character to use
4485     * @return the joined String, {@code null} if null array input
4486     * @since 3.2
4487     */
4488    public static String join(final long[] array, final char separator) {
4489        if (array == null) {
4490            return null;
4491        }
4492        return join(array, separator, 0, array.length);
4493    }
4494
4495    /**
4496     * Joins the elements of the provided array into a single String containing the provided list of elements.
4497     *
4498     * <p>
4499     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4500     * by empty strings.
4501     * </p>
4502     *
4503     * <pre>
4504     * StringUtils.join(null, *)               = null
4505     * StringUtils.join([], *)                 = ""
4506     * StringUtils.join([null], *)             = ""
4507     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4508     * StringUtils.join([1, 2, 3], null) = "123"
4509     * </pre>
4510     *
4511     * @param array
4512     *            the array of values to join together, may be null
4513     * @param delimiter
4514     *            the separator character to use
4515     * @param startIndex
4516     *            the first index to start joining from. It is an error to pass in a start index past the end of the
4517     *            array
4518     * @param endIndex
4519     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
4520     *            the array
4521     * @return the joined String, {@code null} if null array input
4522     * @since 3.2
4523     */
4524    public static String join(final long[] array, final char delimiter, final int startIndex, final int endIndex) {
4525        if (array == null) {
4526            return null;
4527        }
4528        if (endIndex - startIndex <= 0) {
4529            return EMPTY;
4530        }
4531        final StringBuilder stringBuilder = new StringBuilder();
4532        for (int i = startIndex; i < endIndex; i++) {
4533            stringBuilder
4534                    .append(array[i])
4535                    .append(delimiter);
4536        }
4537        return stringBuilder.substring(0, stringBuilder.length() - 1);
4538    }
4539
4540    /**
4541     * Joins the elements of the provided array into a single String
4542     * containing the provided list of elements.
4543     *
4544     * <p>No delimiter is added before or after the list.
4545     * Null objects or empty strings within the array are represented by
4546     * empty strings.</p>
4547     *
4548     * <pre>
4549     * StringUtils.join(null, *)               = null
4550     * StringUtils.join([], *)                 = ""
4551     * StringUtils.join([null], *)             = ""
4552     * StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
4553     * StringUtils.join(["a", "b", "c"], null) = "abc"
4554     * StringUtils.join([null, "", "a"], ';')  = ";;a"
4555     * </pre>
4556     *
4557     * @param array  the array of values to join together, may be null
4558     * @param delimiter  the separator character to use
4559     * @return the joined String, {@code null} if null array input
4560     * @since 2.0
4561     */
4562    public static String join(final Object[] array, final char delimiter) {
4563        if (array == null) {
4564            return null;
4565        }
4566        return join(array, delimiter, 0, array.length);
4567    }
4568
4569    /**
4570     * Joins the elements of the provided array into a single String
4571     * containing the provided list of elements.
4572     *
4573     * <p>No delimiter is added before or after the list.
4574     * Null objects or empty strings within the array are represented by
4575     * empty strings.</p>
4576     *
4577     * <pre>
4578     * StringUtils.join(null, *)               = null
4579     * StringUtils.join([], *)                 = ""
4580     * StringUtils.join([null], *)             = ""
4581     * StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
4582     * StringUtils.join(["a", "b", "c"], null) = "abc"
4583     * StringUtils.join([null, "", "a"], ';')  = ";;a"
4584     * </pre>
4585     *
4586     * @param array  the array of values to join together, may be null
4587     * @param delimiter  the separator character to use
4588     * @param startIndex the first index to start joining from.  It is
4589     * an error to pass in a start index past the end of the array
4590     * @param endIndex the index to stop joining from (exclusive). It is
4591     * an error to pass in an end index past the end of the array
4592     * @return the joined String, {@code null} if null array input
4593     * @since 2.0
4594     */
4595    public static String join(final Object[] array, final char delimiter, final int startIndex, final int endIndex) {
4596        return join(array, String.valueOf(delimiter), startIndex, endIndex);
4597    }
4598
4599    /**
4600     * Joins the elements of the provided array into a single String
4601     * containing the provided list of elements.
4602     *
4603     * <p>No delimiter is added before or after the list.
4604     * A {@code null} separator is the same as an empty String ("").
4605     * Null objects or empty strings within the array are represented by
4606     * empty strings.</p>
4607     *
4608     * <pre>
4609     * StringUtils.join(null, *)                = null
4610     * StringUtils.join([], *)                  = ""
4611     * StringUtils.join([null], *)              = ""
4612     * StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
4613     * StringUtils.join(["a", "b", "c"], null)  = "abc"
4614     * StringUtils.join(["a", "b", "c"], "")    = "abc"
4615     * StringUtils.join([null, "", "a"], ',')   = ",,a"
4616     * </pre>
4617     *
4618     * @param array  the array of values to join together, may be null
4619     * @param delimiter  the separator character to use, null treated as ""
4620     * @return the joined String, {@code null} if null array input
4621     */
4622    public static String join(final Object[] array, final String delimiter) {
4623        return array != null ? join(array, toStringOrEmpty(delimiter), 0, array.length) : null;
4624    }
4625
4626    /**
4627     * Joins the elements of the provided array into a single String
4628     * containing the provided list of elements.
4629     *
4630     * <p>No delimiter is added before or after the list.
4631     * A {@code null} separator is the same as an empty String ("").
4632     * Null objects or empty strings within the array are represented by
4633     * empty strings.</p>
4634     *
4635     * <pre>
4636     * StringUtils.join(null, *, *, *)                = null
4637     * StringUtils.join([], *, *, *)                  = ""
4638     * StringUtils.join([null], *, *, *)              = ""
4639     * StringUtils.join(["a", "b", "c"], "--", 0, 3)  = "a--b--c"
4640     * StringUtils.join(["a", "b", "c"], "--", 1, 3)  = "b--c"
4641     * StringUtils.join(["a", "b", "c"], "--", 2, 3)  = "c"
4642     * StringUtils.join(["a", "b", "c"], "--", 2, 2)  = ""
4643     * StringUtils.join(["a", "b", "c"], null, 0, 3)  = "abc"
4644     * StringUtils.join(["a", "b", "c"], "", 0, 3)    = "abc"
4645     * StringUtils.join([null, "", "a"], ',', 0, 3)   = ",,a"
4646     * </pre>
4647     *
4648     * @param array  the array of values to join together, may be null
4649     * @param delimiter  the separator character to use, null treated as ""
4650     * @param startIndex the first index to start joining from.
4651     * @param endIndex the index to stop joining from (exclusive).
4652     * @return the joined String, {@code null} if null array input; or the empty string
4653     * if {@code endIndex - startIndex <= 0}. The number of joined entries is given by
4654     * {@code endIndex - startIndex}
4655     * @throws ArrayIndexOutOfBoundsException ife<br>
4656     * {@code startIndex < 0} or <br>
4657     * {@code startIndex >= array.length()} or <br>
4658     * {@code endIndex < 0} or <br>
4659     * {@code endIndex > array.length()}
4660     */
4661    public static String join(final Object[] array, final String delimiter, final int startIndex, final int endIndex) {
4662        return array != null ? Streams.of(array).skip(startIndex).limit(Math.max(0, endIndex - startIndex))
4663            .collect(LangCollectors.joining(delimiter, EMPTY, EMPTY, StringUtils::toStringOrEmpty)) : null;
4664    }
4665
4666    /**
4667     * Joins the elements of the provided array into a single String containing the provided list of elements.
4668     *
4669     * <p>
4670     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4671     * by empty strings.
4672     * </p>
4673     *
4674     * <pre>
4675     * StringUtils.join(null, *)               = null
4676     * StringUtils.join([], *)                 = ""
4677     * StringUtils.join([null], *)             = ""
4678     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4679     * StringUtils.join([1, 2, 3], null) = "123"
4680     * </pre>
4681     *
4682     * @param array
4683     *            the array of values to join together, may be null
4684     * @param delimiter
4685     *            the separator character to use
4686     * @return the joined String, {@code null} if null array input
4687     * @since 3.2
4688     */
4689    public static String join(final short[] array, final char delimiter) {
4690        if (array == null) {
4691            return null;
4692        }
4693        return join(array, delimiter, 0, array.length);
4694    }
4695
4696    /**
4697     * Joins the elements of the provided array into a single String containing the provided list of elements.
4698     *
4699     * <p>
4700     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
4701     * by empty strings.
4702     * </p>
4703     *
4704     * <pre>
4705     * StringUtils.join(null, *)               = null
4706     * StringUtils.join([], *)                 = ""
4707     * StringUtils.join([null], *)             = ""
4708     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
4709     * StringUtils.join([1, 2, 3], null) = "123"
4710     * </pre>
4711     *
4712     * @param array
4713     *            the array of values to join together, may be null
4714     * @param delimiter
4715     *            the separator character to use
4716     * @param startIndex
4717     *            the first index to start joining from. It is an error to pass in a start index past the end of the
4718     *            array
4719     * @param endIndex
4720     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
4721     *            the array
4722     * @return the joined String, {@code null} if null array input
4723     * @since 3.2
4724     */
4725    public static String join(final short[] array, final char delimiter, final int startIndex, final int endIndex) {
4726        if (array == null) {
4727            return null;
4728        }
4729        if (endIndex - startIndex <= 0) {
4730            return EMPTY;
4731        }
4732        final StringBuilder stringBuilder = new StringBuilder();
4733        for (int i = startIndex; i < endIndex; i++) {
4734            stringBuilder
4735                    .append(array[i])
4736                    .append(delimiter);
4737        }
4738        return stringBuilder.substring(0, stringBuilder.length() - 1);
4739    }
4740
4741    /**
4742     * Joins the elements of the provided array into a single String
4743     * containing the provided list of elements.
4744     *
4745     * <p>No separator is added to the joined String.
4746     * Null objects or empty strings within the array are represented by
4747     * empty strings.</p>
4748     *
4749     * <pre>
4750     * StringUtils.join(null)            = null
4751     * StringUtils.join([])              = ""
4752     * StringUtils.join([null])          = ""
4753     * StringUtils.join(["a", "b", "c"]) = "abc"
4754     * StringUtils.join([null, "", "a"]) = "a"
4755     * </pre>
4756     *
4757     * @param <T> the specific type of values to join together
4758     * @param elements  the values to join together, may be null
4759     * @return the joined String, {@code null} if null array input
4760     * @since 2.0
4761     * @since 3.0 Changed signature to use varargs
4762     */
4763    @SafeVarargs
4764    public static <T> String join(final T... elements) {
4765        return join(elements, null);
4766    }
4767
4768    /**
4769     * Joins the elements of the provided varargs into a
4770     * single String containing the provided elements.
4771     *
4772     * <p>No delimiter is added before or after the list.
4773     * {@code null} elements and separator are treated as empty Strings ("").</p>
4774     *
4775     * <pre>
4776     * StringUtils.joinWith(",", {"a", "b"})        = "a,b"
4777     * StringUtils.joinWith(",", {"a", "b",""})     = "a,b,"
4778     * StringUtils.joinWith(",", {"a", null, "b"})  = "a,,b"
4779     * StringUtils.joinWith(null, {"a", "b"})       = "ab"
4780     * </pre>
4781     *
4782     * @param delimiter the separator character to use, null treated as ""
4783     * @param array the varargs providing the values to join together. {@code null} elements are treated as ""
4784     * @return the joined String.
4785     * @throws IllegalArgumentException if a null varargs is provided
4786     * @since 3.5
4787     */
4788    public static String joinWith(final String delimiter, final Object... array) {
4789        if (array == null) {
4790            throw new IllegalArgumentException("Object varargs must not be null");
4791        }
4792        return join(array, delimiter);
4793    }
4794
4795    /**
4796     * Finds the last index within a CharSequence, handling {@code null}.
4797     * This method uses {@link String#lastIndexOf(String)} if possible.
4798     *
4799     * <p>A {@code null} CharSequence will return {@code -1}.</p>
4800     *
4801     * <pre>
4802     * StringUtils.lastIndexOf(null, *)          = -1
4803     * StringUtils.lastIndexOf(*, null)          = -1
4804     * StringUtils.lastIndexOf("", "")           = 0
4805     * StringUtils.lastIndexOf("aabaabaa", "a")  = 7
4806     * StringUtils.lastIndexOf("aabaabaa", "b")  = 5
4807     * StringUtils.lastIndexOf("aabaabaa", "ab") = 4
4808     * StringUtils.lastIndexOf("aabaabaa", "")   = 8
4809     * </pre>
4810     *
4811     * @param seq  the CharSequence to check, may be null
4812     * @param searchSeq  the CharSequence to find, may be null
4813     * @return the last index of the search String,
4814     *  -1 if no match or {@code null} string input
4815     * @since 2.0
4816     * @since 3.0 Changed signature from lastIndexOf(String, String) to lastIndexOf(CharSequence, CharSequence)
4817     */
4818    public static int lastIndexOf(final CharSequence seq, final CharSequence searchSeq) {
4819        if (seq == null) {
4820            return INDEX_NOT_FOUND;
4821        }
4822        return CharSequenceUtils.lastIndexOf(seq, searchSeq, seq.length());
4823    }
4824
4825    /**
4826     * Finds the last index within a CharSequence, handling {@code null}.
4827     * This method uses {@link String#lastIndexOf(String, int)} if possible.
4828     *
4829     * <p>A {@code null} CharSequence will return {@code -1}.
4830     * A negative start position returns {@code -1}.
4831     * An empty ("") search CharSequence always matches unless the start position is negative.
4832     * A start position greater than the string length searches the whole string.
4833     * The search starts at the startPos and works backwards; matches starting after the start
4834     * position are ignored.
4835     * </p>
4836     *
4837     * <pre>
4838     * StringUtils.lastIndexOf(null, *, *)          = -1
4839     * StringUtils.lastIndexOf(*, null, *)          = -1
4840     * StringUtils.lastIndexOf("aabaabaa", "a", 8)  = 7
4841     * StringUtils.lastIndexOf("aabaabaa", "b", 8)  = 5
4842     * StringUtils.lastIndexOf("aabaabaa", "ab", 8) = 4
4843     * StringUtils.lastIndexOf("aabaabaa", "b", 9)  = 5
4844     * StringUtils.lastIndexOf("aabaabaa", "b", -1) = -1
4845     * StringUtils.lastIndexOf("aabaabaa", "a", 0)  = 0
4846     * StringUtils.lastIndexOf("aabaabaa", "b", 0)  = -1
4847     * StringUtils.lastIndexOf("aabaabaa", "b", 1)  = -1
4848     * StringUtils.lastIndexOf("aabaabaa", "b", 2)  = 2
4849     * StringUtils.lastIndexOf("aabaabaa", "ba", 2)  = 2
4850     * </pre>
4851     *
4852     * @param seq  the CharSequence to check, may be null
4853     * @param searchSeq  the CharSequence to find, may be null
4854     * @param startPos  the start position, negative treated as zero
4855     * @return the last index of the search CharSequence (always &le; startPos),
4856     *  -1 if no match or {@code null} string input
4857     * @since 2.0
4858     * @since 3.0 Changed signature from lastIndexOf(String, String, int) to lastIndexOf(CharSequence, CharSequence, int)
4859     */
4860    public static int lastIndexOf(final CharSequence seq, final CharSequence searchSeq, final int startPos) {
4861        return CharSequenceUtils.lastIndexOf(seq, searchSeq, startPos);
4862    }
4863
4864    /**
4865     * Returns the index within {@code seq} of the last occurrence of
4866     * the specified character. For values of {@code searchChar} in the
4867     * range from 0 to 0xFFFF (inclusive), the index (in Unicode code
4868     * units) returned is the largest value <i>k</i> such that:
4869     * <blockquote><pre>
4870     * this.charAt(<i>k</i>) == searchChar
4871     * </pre></blockquote>
4872     * is true. For other values of {@code searchChar}, it is the
4873     * largest value <i>k</i> such that:
4874     * <blockquote><pre>
4875     * this.codePointAt(<i>k</i>) == searchChar
4876     * </pre></blockquote>
4877     * is true.  In either case, if no such character occurs in this
4878     * string, then {@code -1} is returned. Furthermore, a {@code null} or empty ("")
4879     * {@link CharSequence} will return {@code -1}. The
4880     * {@code seq} {@link CharSequence} object is searched backwards
4881     * starting at the last character.
4882     *
4883     * <pre>
4884     * StringUtils.lastIndexOf(null, *)         = -1
4885     * StringUtils.lastIndexOf("", *)           = -1
4886     * StringUtils.lastIndexOf("aabaabaa", 'a') = 7
4887     * StringUtils.lastIndexOf("aabaabaa", 'b') = 5
4888     * </pre>
4889     *
4890     * @param seq  the {@link CharSequence} to check, may be null
4891     * @param searchChar  the character to find
4892     * @return the last index of the search character,
4893     *  -1 if no match or {@code null} string input
4894     * @since 2.0
4895     * @since 3.0 Changed signature from lastIndexOf(String, int) to lastIndexOf(CharSequence, int)
4896     * @since 3.6 Updated {@link CharSequenceUtils} call to behave more like {@link String}
4897     */
4898    public static int lastIndexOf(final CharSequence seq, final int searchChar) {
4899        if (isEmpty(seq)) {
4900            return INDEX_NOT_FOUND;
4901        }
4902        return CharSequenceUtils.lastIndexOf(seq, searchChar, seq.length());
4903    }
4904
4905    /**
4906     * Returns the index within {@code seq} of the last occurrence of
4907     * the specified character, searching backward starting at the
4908     * specified index. For values of {@code searchChar} in the range
4909     * from 0 to 0xFFFF (inclusive), the index returned is the largest
4910     * value <i>k</i> such that:
4911     * <blockquote><pre>
4912     * (this.charAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &lt;= startPos)
4913     * </pre></blockquote>
4914     * is true. For other values of {@code searchChar}, it is the
4915     * largest value <i>k</i> such that:
4916     * <blockquote><pre>
4917     * (this.codePointAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &lt;= startPos)
4918     * </pre></blockquote>
4919     * is true. In either case, if no such character occurs in {@code seq}
4920     * at or before position {@code startPos}, then
4921     * {@code -1} is returned. Furthermore, a {@code null} or empty ("")
4922     * {@link CharSequence} will return {@code -1}. A start position greater
4923     * than the string length searches the whole string.
4924     * The search starts at the {@code startPos} and works backwards;
4925     * matches starting after the start position are ignored.
4926     *
4927     * <p>All indices are specified in {@code char} values
4928     * (Unicode code units).
4929     *
4930     * <pre>
4931     * StringUtils.lastIndexOf(null, *, *)          = -1
4932     * StringUtils.lastIndexOf("", *,  *)           = -1
4933     * StringUtils.lastIndexOf("aabaabaa", 'b', 8)  = 5
4934     * StringUtils.lastIndexOf("aabaabaa", 'b', 4)  = 2
4935     * StringUtils.lastIndexOf("aabaabaa", 'b', 0)  = -1
4936     * StringUtils.lastIndexOf("aabaabaa", 'b', 9)  = 5
4937     * StringUtils.lastIndexOf("aabaabaa", 'b', -1) = -1
4938     * StringUtils.lastIndexOf("aabaabaa", 'a', 0)  = 0
4939     * </pre>
4940     *
4941     * @param seq  the CharSequence to check, may be null
4942     * @param searchChar  the character to find
4943     * @param startPos  the start position
4944     * @return the last index of the search character (always &le; startPos),
4945     *  -1 if no match or {@code null} string input
4946     * @since 2.0
4947     * @since 3.0 Changed signature from lastIndexOf(String, int, int) to lastIndexOf(CharSequence, int, int)
4948     */
4949    public static int lastIndexOf(final CharSequence seq, final int searchChar, final int startPos) {
4950        if (isEmpty(seq)) {
4951            return INDEX_NOT_FOUND;
4952        }
4953        return CharSequenceUtils.lastIndexOf(seq, searchChar, startPos);
4954    }
4955
4956    /**
4957     * Find the latest index of any substring in a set of potential substrings.
4958     *
4959     * <p>A {@code null} CharSequence will return {@code -1}.
4960     * A {@code null} search array will return {@code -1}.
4961     * A {@code null} or zero length search array entry will be ignored,
4962     * but a search array containing "" will return the length of {@code str}
4963     * if {@code str} is not null. This method uses {@link String#indexOf(String)} if possible</p>
4964     *
4965     * <pre>
4966     * StringUtils.lastIndexOfAny(null, *)                    = -1
4967     * StringUtils.lastIndexOfAny(*, null)                    = -1
4968     * StringUtils.lastIndexOfAny(*, [])                      = -1
4969     * StringUtils.lastIndexOfAny(*, [null])                  = -1
4970     * StringUtils.lastIndexOfAny("zzabyycdxx", ["ab", "cd"]) = 6
4971     * StringUtils.lastIndexOfAny("zzabyycdxx", ["cd", "ab"]) = 6
4972     * StringUtils.lastIndexOfAny("zzabyycdxx", ["mn", "op"]) = -1
4973     * StringUtils.lastIndexOfAny("zzabyycdxx", ["mn", "op"]) = -1
4974     * StringUtils.lastIndexOfAny("zzabyycdxx", ["mn", ""])   = 10
4975     * </pre>
4976     *
4977     * @param str  the CharSequence to check, may be null
4978     * @param searchStrs  the CharSequences to search for, may be null
4979     * @return the last index of any of the CharSequences, -1 if no match
4980     * @since 3.0 Changed signature from lastIndexOfAny(String, String[]) to lastIndexOfAny(CharSequence, CharSequence)
4981     */
4982    public static int lastIndexOfAny(final CharSequence str, final CharSequence... searchStrs) {
4983        if (str == null || searchStrs == null) {
4984            return INDEX_NOT_FOUND;
4985        }
4986        int ret = INDEX_NOT_FOUND;
4987        int tmp;
4988        for (final CharSequence search : searchStrs) {
4989            if (search == null) {
4990                continue;
4991            }
4992            tmp = CharSequenceUtils.lastIndexOf(str, search, str.length());
4993            if (tmp > ret) {
4994                ret = tmp;
4995            }
4996        }
4997        return ret;
4998    }
4999
5000    /**
5001     * Case in-sensitive find of the last index within a CharSequence.
5002     *
5003     * <p>A {@code null} CharSequence will return {@code -1}.
5004     * A negative start position returns {@code -1}.
5005     * An empty ("") search CharSequence always matches unless the start position is negative.
5006     * A start position greater than the string length searches the whole string.</p>
5007     *
5008     * <pre>
5009     * StringUtils.lastIndexOfIgnoreCase(null, *)          = -1
5010     * StringUtils.lastIndexOfIgnoreCase(*, null)          = -1
5011     * StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A")  = 7
5012     * StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B")  = 5
5013     * StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB") = 4
5014     * </pre>
5015     *
5016     * @param str  the CharSequence to check, may be null
5017     * @param searchStr  the CharSequence to find, may be null
5018     * @return the first index of the search CharSequence,
5019     *  -1 if no match or {@code null} string input
5020     * @since 2.5
5021     * @since 3.0 Changed signature from lastIndexOfIgnoreCase(String, String) to lastIndexOfIgnoreCase(CharSequence, CharSequence)
5022     */
5023    public static int lastIndexOfIgnoreCase(final CharSequence str, final CharSequence searchStr) {
5024        if (str == null || searchStr == null) {
5025            return INDEX_NOT_FOUND;
5026        }
5027        return lastIndexOfIgnoreCase(str, searchStr, str.length());
5028    }
5029
5030    /**
5031     * Case in-sensitive find of the last index within a CharSequence
5032     * from the specified position.
5033     *
5034     * <p>A {@code null} CharSequence will return {@code -1}.
5035     * A negative start position returns {@code -1}.
5036     * An empty ("") search CharSequence always matches unless the start position is negative.
5037     * A start position greater than the string length searches the whole string.
5038     * The search starts at the startPos and works backwards; matches starting after the start
5039     * position are ignored.
5040     * </p>
5041     *
5042     * <pre>
5043     * StringUtils.lastIndexOfIgnoreCase(null, *, *)          = -1
5044     * StringUtils.lastIndexOfIgnoreCase(*, null, *)          = -1
5045     * StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 8)  = 7
5046     * StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 8)  = 5
5047     * StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB", 8) = 4
5048     * StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 9)  = 5
5049     * StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", -1) = -1
5050     * StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 0)  = 0
5051     * StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 0)  = -1
5052     * </pre>
5053     *
5054     * @param str  the CharSequence to check, may be null
5055     * @param searchStr  the CharSequence to find, may be null
5056     * @param startPos  the start position
5057     * @return the last index of the search CharSequence (always &le; startPos),
5058     *  -1 if no match or {@code null} input
5059     * @since 2.5
5060     * @since 3.0 Changed signature from lastIndexOfIgnoreCase(String, String, int) to lastIndexOfIgnoreCase(CharSequence, CharSequence, int)
5061     */
5062    public static int lastIndexOfIgnoreCase(final CharSequence str, final CharSequence searchStr, int startPos) {
5063        if (str == null || searchStr == null) {
5064            return INDEX_NOT_FOUND;
5065        }
5066        final int searchStrLength = searchStr.length();
5067        final int strLength = str.length();
5068        if (startPos > strLength - searchStrLength) {
5069            startPos = strLength - searchStrLength;
5070        }
5071        if (startPos < 0) {
5072            return INDEX_NOT_FOUND;
5073        }
5074        if (searchStrLength == 0) {
5075            return startPos;
5076        }
5077
5078        for (int i = startPos; i >= 0; i--) {
5079            if (CharSequenceUtils.regionMatches(str, true, i, searchStr, 0, searchStrLength)) {
5080                return i;
5081            }
5082        }
5083        return INDEX_NOT_FOUND;
5084    }
5085
5086    /**
5087     * Finds the n-th last index within a String, handling {@code null}.
5088     * This method uses {@link String#lastIndexOf(String)}.
5089     *
5090     * <p>A {@code null} String will return {@code -1}.</p>
5091     *
5092     * <pre>
5093     * StringUtils.lastOrdinalIndexOf(null, *, *)          = -1
5094     * StringUtils.lastOrdinalIndexOf(*, null, *)          = -1
5095     * StringUtils.lastOrdinalIndexOf("", "", *)           = 0
5096     * StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 1)  = 7
5097     * StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 2)  = 6
5098     * StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 1)  = 5
5099     * StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 2)  = 2
5100     * StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 1) = 4
5101     * StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 2) = 1
5102     * StringUtils.lastOrdinalIndexOf("aabaabaa", "", 1)   = 8
5103     * StringUtils.lastOrdinalIndexOf("aabaabaa", "", 2)   = 8
5104     * </pre>
5105     *
5106     * <p>Note that 'tail(CharSequence str, int n)' may be implemented as: </p>
5107     *
5108     * <pre>
5109     *   str.substring(lastOrdinalIndexOf(str, "\n", n) + 1)
5110     * </pre>
5111     *
5112     * @param str  the CharSequence to check, may be null
5113     * @param searchStr  the CharSequence to find, may be null
5114     * @param ordinal  the n-th last {@code searchStr} to find
5115     * @return the n-th last index of the search CharSequence,
5116     *  {@code -1} ({@code INDEX_NOT_FOUND}) if no match or {@code null} string input
5117     * @since 2.5
5118     * @since 3.0 Changed signature from lastOrdinalIndexOf(String, String, int) to lastOrdinalIndexOf(CharSequence, CharSequence, int)
5119     */
5120    public static int lastOrdinalIndexOf(final CharSequence str, final CharSequence searchStr, final int ordinal) {
5121        return ordinalIndexOf(str, searchStr, ordinal, true);
5122    }
5123
5124    /**
5125     * Gets the leftmost {@code len} characters of a String.
5126     *
5127     * <p>If {@code len} characters are not available, or the
5128     * String is {@code null}, the String will be returned without
5129     * an exception. An empty String is returned if len is negative.</p>
5130     *
5131     * <pre>
5132     * StringUtils.left(null, *)    = null
5133     * StringUtils.left(*, -ve)     = ""
5134     * StringUtils.left("", *)      = ""
5135     * StringUtils.left("abc", 0)   = ""
5136     * StringUtils.left("abc", 2)   = "ab"
5137     * StringUtils.left("abc", 4)   = "abc"
5138     * </pre>
5139     *
5140     * @param str  the String to get the leftmost characters from, may be null
5141     * @param len  the length of the required String
5142     * @return the leftmost characters, {@code null} if null String input
5143     */
5144    public static String left(final String str, final int len) {
5145        if (str == null) {
5146            return null;
5147        }
5148        if (len < 0) {
5149            return EMPTY;
5150        }
5151        if (str.length() <= len) {
5152            return str;
5153        }
5154        return str.substring(0, len);
5155    }
5156
5157    /**
5158     * Left pad a String with spaces (' ').
5159     *
5160     * <p>The String is padded to the size of {@code size}.</p>
5161     *
5162     * <pre>
5163     * StringUtils.leftPad(null, *)   = null
5164     * StringUtils.leftPad("", 3)     = "   "
5165     * StringUtils.leftPad("bat", 3)  = "bat"
5166     * StringUtils.leftPad("bat", 5)  = "  bat"
5167     * StringUtils.leftPad("bat", 1)  = "bat"
5168     * StringUtils.leftPad("bat", -1) = "bat"
5169     * </pre>
5170     *
5171     * @param str  the String to pad out, may be null
5172     * @param size  the size to pad to
5173     * @return left padded String or original String if no padding is necessary,
5174     *  {@code null} if null String input
5175     */
5176    public static String leftPad(final String str, final int size) {
5177        return leftPad(str, size, ' ');
5178    }
5179
5180    /**
5181     * Left pad a String with a specified character.
5182     *
5183     * <p>Pad to a size of {@code size}.</p>
5184     *
5185     * <pre>
5186     * StringUtils.leftPad(null, *, *)     = null
5187     * StringUtils.leftPad("", 3, 'z')     = "zzz"
5188     * StringUtils.leftPad("bat", 3, 'z')  = "bat"
5189     * StringUtils.leftPad("bat", 5, 'z')  = "zzbat"
5190     * StringUtils.leftPad("bat", 1, 'z')  = "bat"
5191     * StringUtils.leftPad("bat", -1, 'z') = "bat"
5192     * </pre>
5193     *
5194     * @param str  the String to pad out, may be null
5195     * @param size  the size to pad to
5196     * @param padChar  the character to pad with
5197     * @return left padded String or original String if no padding is necessary,
5198     *  {@code null} if null String input
5199     * @since 2.0
5200     */
5201    public static String leftPad(final String str, final int size, final char padChar) {
5202        if (str == null) {
5203            return null;
5204        }
5205        final int pads = size - str.length();
5206        if (pads <= 0) {
5207            return str; // returns original String when possible
5208        }
5209        if (pads > PAD_LIMIT) {
5210            return leftPad(str, size, String.valueOf(padChar));
5211        }
5212        return repeat(padChar, pads).concat(str);
5213    }
5214
5215    /**
5216     * Left pad a String with a specified String.
5217     *
5218     * <p>Pad to a size of {@code size}.</p>
5219     *
5220     * <pre>
5221     * StringUtils.leftPad(null, *, *)      = null
5222     * StringUtils.leftPad("", 3, "z")      = "zzz"
5223     * StringUtils.leftPad("bat", 3, "yz")  = "bat"
5224     * StringUtils.leftPad("bat", 5, "yz")  = "yzbat"
5225     * StringUtils.leftPad("bat", 8, "yz")  = "yzyzybat"
5226     * StringUtils.leftPad("bat", 1, "yz")  = "bat"
5227     * StringUtils.leftPad("bat", -1, "yz") = "bat"
5228     * StringUtils.leftPad("bat", 5, null)  = "  bat"
5229     * StringUtils.leftPad("bat", 5, "")    = "  bat"
5230     * </pre>
5231     *
5232     * @param str  the String to pad out, may be null
5233     * @param size  the size to pad to
5234     * @param padStr  the String to pad with, null or empty treated as single space
5235     * @return left padded String or original String if no padding is necessary,
5236     *  {@code null} if null String input
5237     */
5238    public static String leftPad(final String str, final int size, String padStr) {
5239        if (str == null) {
5240            return null;
5241        }
5242        if (isEmpty(padStr)) {
5243            padStr = SPACE;
5244        }
5245        final int padLen = padStr.length();
5246        final int strLen = str.length();
5247        final int pads = size - strLen;
5248        if (pads <= 0) {
5249            return str; // returns original String when possible
5250        }
5251        if (padLen == 1 && pads <= PAD_LIMIT) {
5252            return leftPad(str, size, padStr.charAt(0));
5253        }
5254
5255        if (pads == padLen) {
5256            return padStr.concat(str);
5257        }
5258        if (pads < padLen) {
5259            return padStr.substring(0, pads).concat(str);
5260        }
5261        final char[] padding = new char[pads];
5262        final char[] padChars = padStr.toCharArray();
5263        for (int i = 0; i < pads; i++) {
5264            padding[i] = padChars[i % padLen];
5265        }
5266        return new String(padding).concat(str);
5267    }
5268
5269    /**
5270     * Gets a CharSequence length or {@code 0} if the CharSequence is
5271     * {@code null}.
5272     *
5273     * @param cs
5274     *            a CharSequence or {@code null}
5275     * @return CharSequence length or {@code 0} if the CharSequence is
5276     *         {@code null}.
5277     * @since 2.4
5278     * @since 3.0 Changed signature from length(String) to length(CharSequence)
5279     */
5280    public static int length(final CharSequence cs) {
5281        return cs == null ? 0 : cs.length();
5282    }
5283
5284    /**
5285     * Converts a String to lower case as per {@link String#toLowerCase()}.
5286     *
5287     * <p>A {@code null} input String returns {@code null}.</p>
5288     *
5289     * <pre>
5290     * StringUtils.lowerCase(null)  = null
5291     * StringUtils.lowerCase("")    = ""
5292     * StringUtils.lowerCase("aBc") = "abc"
5293     * </pre>
5294     *
5295     * <p><strong>Note:</strong> As described in the documentation for {@link String#toLowerCase()},
5296     * the result of this method is affected by the current locale.
5297     * For platform-independent case transformations, the method {@link #lowerCase(String, Locale)}
5298     * should be used with a specific locale (e.g. {@link Locale#ENGLISH}).</p>
5299     *
5300     * @param str  the String to lower case, may be null
5301     * @return the lower cased String, {@code null} if null String input
5302     */
5303    public static String lowerCase(final String str) {
5304        if (str == null) {
5305            return null;
5306        }
5307        return str.toLowerCase();
5308    }
5309
5310    /**
5311     * Converts a String to lower case as per {@link String#toLowerCase(Locale)}.
5312     *
5313     * <p>A {@code null} input String returns {@code null}.</p>
5314     *
5315     * <pre>
5316     * StringUtils.lowerCase(null, Locale.ENGLISH)  = null
5317     * StringUtils.lowerCase("", Locale.ENGLISH)    = ""
5318     * StringUtils.lowerCase("aBc", Locale.ENGLISH) = "abc"
5319     * </pre>
5320     *
5321     * @param str  the String to lower case, may be null
5322     * @param locale  the locale that defines the case transformation rules, must not be null
5323     * @return the lower cased String, {@code null} if null String input
5324     * @since 2.5
5325     */
5326    public static String lowerCase(final String str, final Locale locale) {
5327        if (str == null) {
5328            return null;
5329        }
5330        return str.toLowerCase(LocaleUtils.toLocale(locale));
5331    }
5332
5333    private static int[] matches(final CharSequence first, final CharSequence second) {
5334        final CharSequence max;
5335        final CharSequence min;
5336        if (first.length() > second.length()) {
5337            max = first;
5338            min = second;
5339        } else {
5340            max = second;
5341            min = first;
5342        }
5343        final int range = Math.max(max.length() / 2 - 1, 0);
5344        final int[] matchIndexes = new int[min.length()];
5345        Arrays.fill(matchIndexes, -1);
5346        final boolean[] matchFlags = new boolean[max.length()];
5347        int matches = 0;
5348        for (int mi = 0; mi < min.length(); mi++) {
5349            final char c1 = min.charAt(mi);
5350            for (int xi = Math.max(mi - range, 0), xn = Math.min(mi + range + 1, max.length()); xi < xn; xi++) {
5351                if (!matchFlags[xi] && c1 == max.charAt(xi)) {
5352                    matchIndexes[mi] = xi;
5353                    matchFlags[xi] = true;
5354                    matches++;
5355                    break;
5356                }
5357            }
5358        }
5359        final char[] ms1 = new char[matches];
5360        final char[] ms2 = new char[matches];
5361        for (int i = 0, si = 0; i < min.length(); i++) {
5362            if (matchIndexes[i] != -1) {
5363                ms1[si] = min.charAt(i);
5364                si++;
5365            }
5366        }
5367        for (int i = 0, si = 0; i < max.length(); i++) {
5368            if (matchFlags[i]) {
5369                ms2[si] = max.charAt(i);
5370                si++;
5371            }
5372        }
5373        int transpositions = 0;
5374        for (int mi = 0; mi < ms1.length; mi++) {
5375            if (ms1[mi] != ms2[mi]) {
5376                transpositions++;
5377            }
5378        }
5379        int prefix = 0;
5380        for (int mi = 0; mi < min.length(); mi++) {
5381            if (first.charAt(mi) != second.charAt(mi)) {
5382                break;
5383            }
5384            prefix++;
5385        }
5386        return new int[] { matches, transpositions / 2, prefix, max.length() };
5387    }
5388
5389    /**
5390     * Gets {@code len} characters from the middle of a String.
5391     *
5392     * <p>If {@code len} characters are not available, the remainder
5393     * of the String will be returned without an exception. If the
5394     * String is {@code null}, {@code null} will be returned.
5395     * An empty String is returned if len is negative or exceeds the
5396     * length of {@code str}.</p>
5397     *
5398     * <pre>
5399     * StringUtils.mid(null, *, *)    = null
5400     * StringUtils.mid(*, *, -ve)     = ""
5401     * StringUtils.mid("", 0, *)      = ""
5402     * StringUtils.mid("abc", 0, 2)   = "ab"
5403     * StringUtils.mid("abc", 0, 4)   = "abc"
5404     * StringUtils.mid("abc", 2, 4)   = "c"
5405     * StringUtils.mid("abc", 4, 2)   = ""
5406     * StringUtils.mid("abc", -2, 2)  = "ab"
5407     * </pre>
5408     *
5409     * @param str  the String to get the characters from, may be null
5410     * @param pos  the position to start from, negative treated as zero
5411     * @param len  the length of the required String
5412     * @return the middle characters, {@code null} if null String input
5413     */
5414    public static String mid(final String str, int pos, final int len) {
5415        if (str == null) {
5416            return null;
5417        }
5418        if (len < 0 || pos > str.length()) {
5419            return EMPTY;
5420        }
5421        if (pos < 0) {
5422            pos = 0;
5423        }
5424        if (str.length() <= pos + len) {
5425            return str.substring(pos);
5426        }
5427        return str.substring(pos, pos + len);
5428    }
5429
5430    /**
5431     * Similar to <a
5432     * href="https://www.w3.org/TR/xpath/#function-normalize-space">https://www.w3.org/TR/xpath/#function-normalize
5433     * -space</a>
5434     *
5435     * <p>
5436     * The function returns the argument string with whitespace normalized by using
5437     * {@code {@link #trim(String)}} to remove leading and trailing whitespace
5438     * and then replacing sequences of whitespace characters by a single space.
5439     * </p>
5440     * In XML Whitespace characters are the same as those allowed by the <a
5441     * href="https://www.w3.org/TR/REC-xml/#NT-S">S</a> production, which is S ::= (#x20 | #x9 | #xD | #xA)+
5442     * <p>
5443     * Java's regexp pattern \s defines whitespace as [ \t\n\x0B\f\r]
5444     *
5445     * <p>For reference:</p>
5446     * <ul>
5447     * <li>\x0B = vertical tab</li>
5448     * <li>\f = #xC = form feed</li>
5449     * <li>#x20 = space</li>
5450     * <li>#x9 = \t</li>
5451     * <li>#xA = \n</li>
5452     * <li>#xD = \r</li>
5453     * </ul>
5454     *
5455     * <p>
5456     * The difference is that Java's whitespace includes vertical tab and form feed, which this functional will also
5457     * normalize. Additionally {@code {@link #trim(String)}} removes control characters (char &lt;= 32) from both
5458     * ends of this String.
5459     * </p>
5460     *
5461     * @see Pattern
5462     * @see #trim(String)
5463     * @see <a
5464     *      href="https://www.w3.org/TR/xpath/#function-normalize-space">https://www.w3.org/TR/xpath/#function-normalize-space</a>
5465     * @param str the source String to normalize whitespaces from, may be null
5466     * @return the modified string with whitespace normalized, {@code null} if null String input
5467     *
5468     * @since 3.0
5469     */
5470    public static String normalizeSpace(final String str) {
5471        // LANG-1020: Improved performance significantly by normalizing manually instead of using regex
5472        // See https://github.com/librucha/commons-lang-normalizespaces-benchmark for performance test
5473        if (isEmpty(str)) {
5474            return str;
5475        }
5476        final int size = str.length();
5477        final char[] newChars = new char[size];
5478        int count = 0;
5479        int whitespacesCount = 0;
5480        boolean startWhitespaces = true;
5481        for (int i = 0; i < size; i++) {
5482            final char actualChar = str.charAt(i);
5483            final boolean isWhitespace = Character.isWhitespace(actualChar);
5484            if (isWhitespace) {
5485                if (whitespacesCount == 0 && !startWhitespaces) {
5486                    newChars[count++] = SPACE.charAt(0);
5487                }
5488                whitespacesCount++;
5489            } else {
5490                startWhitespaces = false;
5491                newChars[count++] = actualChar == 160 ? 32 : actualChar;
5492                whitespacesCount = 0;
5493            }
5494        }
5495        if (startWhitespaces) {
5496            return EMPTY;
5497        }
5498        return new String(newChars, 0, count - (whitespacesCount > 0 ? 1 : 0)).trim();
5499    }
5500
5501    /**
5502     * Finds the n-th index within a CharSequence, handling {@code null}.
5503     * This method uses {@link String#indexOf(String)} if possible.
5504     * <p><b>Note:</b> The code starts looking for a match at the start of the target,
5505     * incrementing the starting index by one after each successful match
5506     * (unless {@code searchStr} is an empty string in which case the position
5507     * is never incremented and {@code 0} is returned immediately).
5508     * This means that matches may overlap.</p>
5509     * <p>A {@code null} CharSequence will return {@code -1}.</p>
5510     *
5511     * <pre>
5512     * StringUtils.ordinalIndexOf(null, *, *)          = -1
5513     * StringUtils.ordinalIndexOf(*, null, *)          = -1
5514     * StringUtils.ordinalIndexOf("", "", *)           = 0
5515     * StringUtils.ordinalIndexOf("aabaabaa", "a", 1)  = 0
5516     * StringUtils.ordinalIndexOf("aabaabaa", "a", 2)  = 1
5517     * StringUtils.ordinalIndexOf("aabaabaa", "b", 1)  = 2
5518     * StringUtils.ordinalIndexOf("aabaabaa", "b", 2)  = 5
5519     * StringUtils.ordinalIndexOf("aabaabaa", "ab", 1) = 1
5520     * StringUtils.ordinalIndexOf("aabaabaa", "ab", 2) = 4
5521     * StringUtils.ordinalIndexOf("aabaabaa", "", 1)   = 0
5522     * StringUtils.ordinalIndexOf("aabaabaa", "", 2)   = 0
5523     * </pre>
5524     *
5525     * <p>Matches may overlap:</p>
5526     * <pre>
5527     * StringUtils.ordinalIndexOf("ababab", "aba", 1)   = 0
5528     * StringUtils.ordinalIndexOf("ababab", "aba", 2)   = 2
5529     * StringUtils.ordinalIndexOf("ababab", "aba", 3)   = -1
5530     *
5531     * StringUtils.ordinalIndexOf("abababab", "abab", 1) = 0
5532     * StringUtils.ordinalIndexOf("abababab", "abab", 2) = 2
5533     * StringUtils.ordinalIndexOf("abababab", "abab", 3) = 4
5534     * StringUtils.ordinalIndexOf("abababab", "abab", 4) = -1
5535     * </pre>
5536     *
5537     * <p>Note that 'head(CharSequence str, int n)' may be implemented as: </p>
5538     *
5539     * <pre>
5540     *   str.substring(0, lastOrdinalIndexOf(str, "\n", n))
5541     * </pre>
5542     *
5543     * @param str  the CharSequence to check, may be null
5544     * @param searchStr  the CharSequence to find, may be null
5545     * @param ordinal  the n-th {@code searchStr} to find
5546     * @return the n-th index of the search CharSequence,
5547     *  {@code -1} ({@code INDEX_NOT_FOUND}) if no match or {@code null} string input
5548     * @since 2.1
5549     * @since 3.0 Changed signature from ordinalIndexOf(String, String, int) to ordinalIndexOf(CharSequence, CharSequence, int)
5550     */
5551    public static int ordinalIndexOf(final CharSequence str, final CharSequence searchStr, final int ordinal) {
5552        return ordinalIndexOf(str, searchStr, ordinal, false);
5553    }
5554
5555    /**
5556     * Finds the n-th index within a String, handling {@code null}.
5557     * This method uses {@link String#indexOf(String)} if possible.
5558     * <p>Note that matches may overlap<p>
5559     *
5560     * <p>A {@code null} CharSequence will return {@code -1}.</p>
5561     *
5562     * @param str  the CharSequence to check, may be null
5563     * @param searchStr  the CharSequence to find, may be null
5564     * @param ordinal  the n-th {@code searchStr} to find, overlapping matches are allowed.
5565     * @param lastIndex true if lastOrdinalIndexOf() otherwise false if ordinalIndexOf()
5566     * @return the n-th index of the search CharSequence,
5567     *  {@code -1} ({@code INDEX_NOT_FOUND}) if no match or {@code null} string input
5568     */
5569    // Shared code between ordinalIndexOf(String, String, int) and lastOrdinalIndexOf(String, String, int)
5570    private static int ordinalIndexOf(final CharSequence str, final CharSequence searchStr, final int ordinal, final boolean lastIndex) {
5571        if (str == null || searchStr == null || ordinal <= 0) {
5572            return INDEX_NOT_FOUND;
5573        }
5574        if (searchStr.length() == 0) {
5575            return lastIndex ? str.length() : 0;
5576        }
5577        int found = 0;
5578        // set the initial index beyond the end of the string
5579        // this is to allow for the initial index decrement/increment
5580        int index = lastIndex ? str.length() : INDEX_NOT_FOUND;
5581        do {
5582            if (lastIndex) {
5583                index = CharSequenceUtils.lastIndexOf(str, searchStr, index - 1); // step backwards through string
5584            } else {
5585                index = CharSequenceUtils.indexOf(str, searchStr, index + 1); // step forwards through string
5586            }
5587            if (index < 0) {
5588                return index;
5589            }
5590            found++;
5591        } while (found < ordinal);
5592        return index;
5593    }
5594
5595    /**
5596     * Overlays part of a String with another String.
5597     *
5598     * <p>A {@code null} string input returns {@code null}.
5599     * A negative index is treated as zero.
5600     * An index greater than the string length is treated as the string length.
5601     * The start index is always the smaller of the two indices.</p>
5602     *
5603     * <pre>
5604     * StringUtils.overlay(null, *, *, *)            = null
5605     * StringUtils.overlay("", "abc", 0, 0)          = "abc"
5606     * StringUtils.overlay("abcdef", null, 2, 4)     = "abef"
5607     * StringUtils.overlay("abcdef", "", 2, 4)       = "abef"
5608     * StringUtils.overlay("abcdef", "", 4, 2)       = "abef"
5609     * StringUtils.overlay("abcdef", "zzzz", 2, 4)   = "abzzzzef"
5610     * StringUtils.overlay("abcdef", "zzzz", 4, 2)   = "abzzzzef"
5611     * StringUtils.overlay("abcdef", "zzzz", -1, 4)  = "zzzzef"
5612     * StringUtils.overlay("abcdef", "zzzz", 2, 8)   = "abzzzz"
5613     * StringUtils.overlay("abcdef", "zzzz", -2, -3) = "zzzzabcdef"
5614     * StringUtils.overlay("abcdef", "zzzz", 8, 10)  = "abcdefzzzz"
5615     * </pre>
5616     *
5617     * @param str  the String to do overlaying in, may be null
5618     * @param overlay  the String to overlay, may be null
5619     * @param start  the position to start overlaying at
5620     * @param end  the position to stop overlaying before
5621     * @return overlayed String, {@code null} if null String input
5622     * @since 2.0
5623     */
5624    public static String overlay(final String str, String overlay, int start, int end) {
5625        if (str == null) {
5626            return null;
5627        }
5628        if (overlay == null) {
5629            overlay = EMPTY;
5630        }
5631        final int len = str.length();
5632        if (start < 0) {
5633            start = 0;
5634        }
5635        if (start > len) {
5636            start = len;
5637        }
5638        if (end < 0) {
5639            end = 0;
5640        }
5641        if (end > len) {
5642            end = len;
5643        }
5644        if (start > end) {
5645            final int temp = start;
5646            start = end;
5647            end = temp;
5648        }
5649        return str.substring(0, start) +
5650            overlay +
5651            str.substring(end);
5652    }
5653
5654    /**
5655     * Prepends the prefix to the start of the string if the string does not
5656     * already start with any of the prefixes.
5657     *
5658     * @param str The string.
5659     * @param prefix The prefix to prepend to the start of the string.
5660     * @param ignoreCase Indicates whether the compare should ignore case.
5661     * @param prefixes Additional prefixes that are valid (optional).
5662     *
5663     * @return A new String if prefix was prepended, the same string otherwise.
5664     */
5665    private static String prependIfMissing(final String str, final CharSequence prefix, final boolean ignoreCase, final CharSequence... prefixes) {
5666        if (str == null || isEmpty(prefix) || startsWith(str, prefix, ignoreCase)) {
5667            return str;
5668        }
5669        if (ArrayUtils.isNotEmpty(prefixes)) {
5670            for (final CharSequence p : prefixes) {
5671                if (startsWith(str, p, ignoreCase)) {
5672                    return str;
5673                }
5674            }
5675        }
5676        return prefix.toString() + str;
5677    }
5678
5679    /**
5680     * Prepends the prefix to the start of the string if the string does not
5681     * already start with any of the prefixes.
5682     *
5683     * <pre>
5684     * StringUtils.prependIfMissing(null, null) = null
5685     * StringUtils.prependIfMissing("abc", null) = "abc"
5686     * StringUtils.prependIfMissing("", "xyz") = "xyz"
5687     * StringUtils.prependIfMissing("abc", "xyz") = "xyzabc"
5688     * StringUtils.prependIfMissing("xyzabc", "xyz") = "xyzabc"
5689     * StringUtils.prependIfMissing("XYZabc", "xyz") = "xyzXYZabc"
5690     * </pre>
5691     * <p>With additional prefixes,</p>
5692     * <pre>
5693     * StringUtils.prependIfMissing(null, null, null) = null
5694     * StringUtils.prependIfMissing("abc", null, null) = "abc"
5695     * StringUtils.prependIfMissing("", "xyz", null) = "xyz"
5696     * StringUtils.prependIfMissing("abc", "xyz", new CharSequence[]{null}) = "xyzabc"
5697     * StringUtils.prependIfMissing("abc", "xyz", "") = "abc"
5698     * StringUtils.prependIfMissing("abc", "xyz", "mno") = "xyzabc"
5699     * StringUtils.prependIfMissing("xyzabc", "xyz", "mno") = "xyzabc"
5700     * StringUtils.prependIfMissing("mnoabc", "xyz", "mno") = "mnoabc"
5701     * StringUtils.prependIfMissing("XYZabc", "xyz", "mno") = "xyzXYZabc"
5702     * StringUtils.prependIfMissing("MNOabc", "xyz", "mno") = "xyzMNOabc"
5703     * </pre>
5704     *
5705     * @param str The string.
5706     * @param prefix The prefix to prepend to the start of the string.
5707     * @param prefixes Additional prefixes that are valid.
5708     *
5709     * @return A new String if prefix was prepended, the same string otherwise.
5710     *
5711     * @since 3.2
5712     */
5713    public static String prependIfMissing(final String str, final CharSequence prefix, final CharSequence... prefixes) {
5714        return prependIfMissing(str, prefix, false, prefixes);
5715    }
5716
5717    /**
5718     * Prepends the prefix to the start of the string if the string does not
5719     * already start, case-insensitive, with any of the prefixes.
5720     *
5721     * <pre>
5722     * StringUtils.prependIfMissingIgnoreCase(null, null) = null
5723     * StringUtils.prependIfMissingIgnoreCase("abc", null) = "abc"
5724     * StringUtils.prependIfMissingIgnoreCase("", "xyz") = "xyz"
5725     * StringUtils.prependIfMissingIgnoreCase("abc", "xyz") = "xyzabc"
5726     * StringUtils.prependIfMissingIgnoreCase("xyzabc", "xyz") = "xyzabc"
5727     * StringUtils.prependIfMissingIgnoreCase("XYZabc", "xyz") = "XYZabc"
5728     * </pre>
5729     * <p>With additional prefixes,</p>
5730     * <pre>
5731     * StringUtils.prependIfMissingIgnoreCase(null, null, null) = null
5732     * StringUtils.prependIfMissingIgnoreCase("abc", null, null) = "abc"
5733     * StringUtils.prependIfMissingIgnoreCase("", "xyz", null) = "xyz"
5734     * StringUtils.prependIfMissingIgnoreCase("abc", "xyz", new CharSequence[]{null}) = "xyzabc"
5735     * StringUtils.prependIfMissingIgnoreCase("abc", "xyz", "") = "abc"
5736     * StringUtils.prependIfMissingIgnoreCase("abc", "xyz", "mno") = "xyzabc"
5737     * StringUtils.prependIfMissingIgnoreCase("xyzabc", "xyz", "mno") = "xyzabc"
5738     * StringUtils.prependIfMissingIgnoreCase("mnoabc", "xyz", "mno") = "mnoabc"
5739     * StringUtils.prependIfMissingIgnoreCase("XYZabc", "xyz", "mno") = "XYZabc"
5740     * StringUtils.prependIfMissingIgnoreCase("MNOabc", "xyz", "mno") = "MNOabc"
5741     * </pre>
5742     *
5743     * @param str The string.
5744     * @param prefix The prefix to prepend to the start of the string.
5745     * @param prefixes Additional prefixes that are valid (optional).
5746     *
5747     * @return A new String if prefix was prepended, the same string otherwise.
5748     *
5749     * @since 3.2
5750     */
5751    public static String prependIfMissingIgnoreCase(final String str, final CharSequence prefix, final CharSequence... prefixes) {
5752        return prependIfMissing(str, prefix, true, prefixes);
5753    }
5754
5755    /**
5756     * Removes all occurrences of a character from within the source string.
5757     *
5758     * <p>A {@code null} source string will return {@code null}.
5759     * An empty ("") source string will return the empty string.</p>
5760     *
5761     * <pre>
5762     * StringUtils.remove(null, *)       = null
5763     * StringUtils.remove("", *)         = ""
5764     * StringUtils.remove("queued", 'u') = "qeed"
5765     * StringUtils.remove("queued", 'z') = "queued"
5766     * </pre>
5767     *
5768     * @param str  the source String to search, may be null
5769     * @param remove  the char to search for and remove, may be null
5770     * @return the substring with the char removed if found,
5771     *  {@code null} if null String input
5772     * @since 2.1
5773     */
5774    public static String remove(final String str, final char remove) {
5775        if (isEmpty(str) || str.indexOf(remove) == INDEX_NOT_FOUND) {
5776            return str;
5777        }
5778        final char[] chars = str.toCharArray();
5779        int pos = 0;
5780        for (int i = 0; i < chars.length; i++) {
5781            if (chars[i] != remove) {
5782                chars[pos++] = chars[i];
5783            }
5784        }
5785        return new String(chars, 0, pos);
5786    }
5787
5788    /**
5789     * Removes all occurrences of a substring from within the source string.
5790     *
5791     * <p>A {@code null} source string will return {@code null}.
5792     * An empty ("") source string will return the empty string.
5793     * A {@code null} remove string will return the source string.
5794     * An empty ("") remove string will return the source string.</p>
5795     *
5796     * <pre>
5797     * StringUtils.remove(null, *)        = null
5798     * StringUtils.remove("", *)          = ""
5799     * StringUtils.remove(*, null)        = *
5800     * StringUtils.remove(*, "")          = *
5801     * StringUtils.remove("queued", "ue") = "qd"
5802     * StringUtils.remove("queued", "zz") = "queued"
5803     * </pre>
5804     *
5805     * @param str  the source String to search, may be null
5806     * @param remove  the String to search for and remove, may be null
5807     * @return the substring with the string removed if found,
5808     *  {@code null} if null String input
5809     * @since 2.1
5810     */
5811    public static String remove(final String str, final String remove) {
5812        if (isEmpty(str) || isEmpty(remove)) {
5813            return str;
5814        }
5815        return replace(str, remove, EMPTY, -1);
5816    }
5817
5818    /**
5819     * Removes each substring of the text String that matches the given regular expression.
5820     *
5821     * This method is a {@code null} safe equivalent to:
5822     * <ul>
5823     *  <li>{@code text.replaceAll(regex, StringUtils.EMPTY)}</li>
5824     *  <li>{@code Pattern.compile(regex).matcher(text).replaceAll(StringUtils.EMPTY)}</li>
5825     * </ul>
5826     *
5827     * <p>A {@code null} reference passed to this method is a no-op.</p>
5828     *
5829     * <p>Unlike in the {@link #removePattern(String, String)} method, the {@link Pattern#DOTALL} option
5830     * is NOT automatically added.
5831     * To use the DOTALL option prepend {@code "(?s)"} to the regex.
5832     * DOTALL is also known as single-line mode in Perl.</p>
5833     *
5834     * <pre>
5835     * StringUtils.removeAll(null, *)      = null
5836     * StringUtils.removeAll("any", (String) null)  = "any"
5837     * StringUtils.removeAll("any", "")    = "any"
5838     * StringUtils.removeAll("any", ".*")  = ""
5839     * StringUtils.removeAll("any", ".+")  = ""
5840     * StringUtils.removeAll("abc", ".?")  = ""
5841     * StringUtils.removeAll("A&lt;__&gt;\n&lt;__&gt;B", "&lt;.*&gt;")      = "A\nB"
5842     * StringUtils.removeAll("A&lt;__&gt;\n&lt;__&gt;B", "(?s)&lt;.*&gt;")  = "AB"
5843     * StringUtils.removeAll("ABCabc123abc", "[a-z]")     = "ABC123"
5844     * </pre>
5845     *
5846     * @param text  text to remove from, may be null
5847     * @param regex  the regular expression to which this string is to be matched
5848     * @return  the text with any removes processed,
5849     *              {@code null} if null String input
5850     *
5851     * @throws  java.util.regex.PatternSyntaxException
5852     *              if the regular expression's syntax is invalid
5853     *
5854     * @see #replaceAll(String, String, String)
5855     * @see #removePattern(String, String)
5856     * @see String#replaceAll(String, String)
5857     * @see java.util.regex.Pattern
5858     * @see java.util.regex.Pattern#DOTALL
5859     * @since 3.5
5860     *
5861     * @deprecated Moved to RegExUtils.
5862     */
5863    @Deprecated
5864    public static String removeAll(final String text, final String regex) {
5865        return RegExUtils.removeAll(text, regex);
5866    }
5867
5868    /**
5869     * Removes a substring only if it is at the end of a source string,
5870     * otherwise returns the source string.
5871     *
5872     * <p>A {@code null} source string will return {@code null}.
5873     * An empty ("") source string will return the empty string.
5874     * A {@code null} search string will return the source string.</p>
5875     *
5876     * <pre>
5877     * StringUtils.removeEnd(null, *)      = null
5878     * StringUtils.removeEnd("", *)        = ""
5879     * StringUtils.removeEnd(*, null)      = *
5880     * StringUtils.removeEnd("www.domain.com", ".com.")  = "www.domain.com"
5881     * StringUtils.removeEnd("www.domain.com", ".com")   = "www.domain"
5882     * StringUtils.removeEnd("www.domain.com", "domain") = "www.domain.com"
5883     * StringUtils.removeEnd("abc", "")    = "abc"
5884     * </pre>
5885     *
5886     * @param str  the source String to search, may be null
5887     * @param remove  the String to search for and remove, may be null
5888     * @return the substring with the string removed if found,
5889     *  {@code null} if null String input
5890     * @since 2.1
5891     */
5892    public static String removeEnd(final String str, final String remove) {
5893        if (isEmpty(str) || isEmpty(remove)) {
5894            return str;
5895        }
5896        if (str.endsWith(remove)) {
5897            return str.substring(0, str.length() - remove.length());
5898        }
5899        return str;
5900    }
5901
5902    /**
5903     * Case insensitive removal of a substring if it is at the end of a source string,
5904     * otherwise returns the source string.
5905     *
5906     * <p>A {@code null} source string will return {@code null}.
5907     * An empty ("") source string will return the empty string.
5908     * A {@code null} search string will return the source string.</p>
5909     *
5910     * <pre>
5911     * StringUtils.removeEndIgnoreCase(null, *)      = null
5912     * StringUtils.removeEndIgnoreCase("", *)        = ""
5913     * StringUtils.removeEndIgnoreCase(*, null)      = *
5914     * StringUtils.removeEndIgnoreCase("www.domain.com", ".com.")  = "www.domain.com"
5915     * StringUtils.removeEndIgnoreCase("www.domain.com", ".com")   = "www.domain"
5916     * StringUtils.removeEndIgnoreCase("www.domain.com", "domain") = "www.domain.com"
5917     * StringUtils.removeEndIgnoreCase("abc", "")    = "abc"
5918     * StringUtils.removeEndIgnoreCase("www.domain.com", ".COM") = "www.domain")
5919     * StringUtils.removeEndIgnoreCase("www.domain.COM", ".com") = "www.domain")
5920     * </pre>
5921     *
5922     * @param str  the source String to search, may be null
5923     * @param remove  the String to search for (case-insensitive) and remove, may be null
5924     * @return the substring with the string removed if found,
5925     *  {@code null} if null String input
5926     * @since 2.4
5927     */
5928    public static String removeEndIgnoreCase(final String str, final String remove) {
5929        if (isEmpty(str) || isEmpty(remove)) {
5930            return str;
5931        }
5932        if (endsWithIgnoreCase(str, remove)) {
5933            return str.substring(0, str.length() - remove.length());
5934        }
5935        return str;
5936    }
5937
5938    /**
5939     * Removes the first substring of the text string that matches the given regular expression.
5940     *
5941     * This method is a {@code null} safe equivalent to:
5942     * <ul>
5943     *  <li>{@code text.replaceFirst(regex, StringUtils.EMPTY)}</li>
5944     *  <li>{@code Pattern.compile(regex).matcher(text).replaceFirst(StringUtils.EMPTY)}</li>
5945     * </ul>
5946     *
5947     * <p>A {@code null} reference passed to this method is a no-op.</p>
5948     *
5949     * <p>The {@link Pattern#DOTALL} option is NOT automatically added.
5950     * To use the DOTALL option prepend {@code "(?s)"} to the regex.
5951     * DOTALL is also known as single-line mode in Perl.</p>
5952     *
5953     * <pre>
5954     * StringUtils.removeFirst(null, *)      = null
5955     * StringUtils.removeFirst("any", (String) null)  = "any"
5956     * StringUtils.removeFirst("any", "")    = "any"
5957     * StringUtils.removeFirst("any", ".*")  = ""
5958     * StringUtils.removeFirst("any", ".+")  = ""
5959     * StringUtils.removeFirst("abc", ".?")  = "bc"
5960     * StringUtils.removeFirst("A&lt;__&gt;\n&lt;__&gt;B", "&lt;.*&gt;")      = "A\n&lt;__&gt;B"
5961     * StringUtils.removeFirst("A&lt;__&gt;\n&lt;__&gt;B", "(?s)&lt;.*&gt;")  = "AB"
5962     * StringUtils.removeFirst("ABCabc123", "[a-z]")          = "ABCbc123"
5963     * StringUtils.removeFirst("ABCabc123abc", "[a-z]+")      = "ABC123abc"
5964     * </pre>
5965     *
5966     * @param text  text to remove from, may be null
5967     * @param regex  the regular expression to which this string is to be matched
5968     * @return  the text with the first replacement processed,
5969     *              {@code null} if null String input
5970     *
5971     * @throws  java.util.regex.PatternSyntaxException
5972     *              if the regular expression's syntax is invalid
5973     *
5974     * @see #replaceFirst(String, String, String)
5975     * @see String#replaceFirst(String, String)
5976     * @see java.util.regex.Pattern
5977     * @see java.util.regex.Pattern#DOTALL
5978     * @since 3.5
5979     *
5980     * @deprecated Moved to RegExUtils.
5981     */
5982    @Deprecated
5983    public static String removeFirst(final String text, final String regex) {
5984        return replaceFirst(text, regex, EMPTY);
5985    }
5986
5987    /**
5988     * Case insensitive removal of all occurrences of a substring from within
5989     * the source string.
5990     *
5991     * <p>
5992     * A {@code null} source string will return {@code null}. An empty ("")
5993     * source string will return the empty string. A {@code null} remove string
5994     * will return the source string. An empty ("") remove string will return
5995     * the source string.
5996     * </p>
5997     *
5998     * <pre>
5999     * StringUtils.removeIgnoreCase(null, *)        = null
6000     * StringUtils.removeIgnoreCase("", *)          = ""
6001     * StringUtils.removeIgnoreCase(*, null)        = *
6002     * StringUtils.removeIgnoreCase(*, "")          = *
6003     * StringUtils.removeIgnoreCase("queued", "ue") = "qd"
6004     * StringUtils.removeIgnoreCase("queued", "zz") = "queued"
6005     * StringUtils.removeIgnoreCase("quEUed", "UE") = "qd"
6006     * StringUtils.removeIgnoreCase("queued", "zZ") = "queued"
6007     * </pre>
6008     *
6009     * @param str
6010     *            the source String to search, may be null
6011     * @param remove
6012     *            the String to search for (case-insensitive) and remove, may be
6013     *            null
6014     * @return the substring with the string removed if found, {@code null} if
6015     *         null String input
6016     * @since 3.5
6017     */
6018    public static String removeIgnoreCase(final String str, final String remove) {
6019        return replaceIgnoreCase(str, remove, EMPTY, -1);
6020    }
6021
6022    /**
6023     * Removes each substring of the source String that matches the given regular expression using the DOTALL option.
6024     *
6025     * This call is a {@code null} safe equivalent to:
6026     * <ul>
6027     * <li>{@code source.replaceAll(&quot;(?s)&quot; + regex, StringUtils.EMPTY)}</li>
6028     * <li>{@code Pattern.compile(regex, Pattern.DOTALL).matcher(source).replaceAll(StringUtils.EMPTY)}</li>
6029     * </ul>
6030     *
6031     * <p>A {@code null} reference passed to this method is a no-op.</p>
6032     *
6033     * <pre>
6034     * StringUtils.removePattern(null, *)       = null
6035     * StringUtils.removePattern("any", (String) null)   = "any"
6036     * StringUtils.removePattern("A&lt;__&gt;\n&lt;__&gt;B", "&lt;.*&gt;")  = "AB"
6037     * StringUtils.removePattern("ABCabc123", "[a-z]")    = "ABC123"
6038     * </pre>
6039     *
6040     * @param source
6041     *            the source string
6042     * @param regex
6043     *            the regular expression to which this string is to be matched
6044     * @return The resulting {@link String}
6045     * @see #replacePattern(String, String, String)
6046     * @see String#replaceAll(String, String)
6047     * @see Pattern#DOTALL
6048     * @since 3.2
6049     * @since 3.5 Changed {@code null} reference passed to this method is a no-op.
6050     *
6051     * @deprecated Moved to RegExUtils.
6052     */
6053    @Deprecated
6054    public static String removePattern(final String source, final String regex) {
6055        return RegExUtils.removePattern(source, regex);
6056    }
6057
6058    /**
6059     * Removes a char only if it is at the beginning of a source string,
6060     * otherwise returns the source string.
6061     *
6062     * <p>A {@code null} source string will return {@code null}.
6063     * An empty ("") source string will return the empty string.
6064     * A {@code null} search char will return the source string.</p>
6065     *
6066     * <pre>
6067     * StringUtils.removeStart(null, *)      = null
6068     * StringUtils.removeStart("", *)        = ""
6069     * StringUtils.removeStart(*, null)      = *
6070     * StringUtils.removeStart("/path", '/') = "path"
6071     * StringUtils.removeStart("path", '/')  = "path"
6072     * StringUtils.removeStart("path", 0)    = "path"
6073     * </pre>
6074     *
6075     * @param str  the source String to search, may be null.
6076     * @param remove  the char to search for and remove.
6077     * @return the substring with the char removed if found,
6078     *  {@code null} if null String input.
6079     * @since 3.13.0
6080     */
6081    public static String removeStart(final String str, final char remove) {
6082        if (isEmpty(str)) {
6083            return str;
6084        }
6085        return str.charAt(0) == remove ? str.substring(1) : str;
6086    }
6087
6088    /**
6089     * Removes a substring only if it is at the beginning of a source string,
6090     * otherwise returns the source string.
6091     *
6092     * <p>A {@code null} source string will return {@code null}.
6093     * An empty ("") source string will return the empty string.
6094     * A {@code null} search string will return the source string.</p>
6095     *
6096     * <pre>
6097     * StringUtils.removeStart(null, *)      = null
6098     * StringUtils.removeStart("", *)        = ""
6099     * StringUtils.removeStart(*, null)      = *
6100     * StringUtils.removeStart("www.domain.com", "www.")   = "domain.com"
6101     * StringUtils.removeStart("domain.com", "www.")       = "domain.com"
6102     * StringUtils.removeStart("www.domain.com", "domain") = "www.domain.com"
6103     * StringUtils.removeStart("abc", "")    = "abc"
6104     * </pre>
6105     *
6106     * @param str  the source String to search, may be null
6107     * @param remove  the String to search for and remove, may be null
6108     * @return the substring with the string removed if found,
6109     *  {@code null} if null String input
6110     * @since 2.1
6111     */
6112    public static String removeStart(final String str, final String remove) {
6113        if (isEmpty(str) || isEmpty(remove)) {
6114            return str;
6115        }
6116        if (str.startsWith(remove)) {
6117            return str.substring(remove.length());
6118        }
6119        return str;
6120    }
6121
6122    /**
6123     * Case insensitive removal of a substring if it is at the beginning of a source string,
6124     * otherwise returns the source string.
6125     *
6126     * <p>A {@code null} source string will return {@code null}.
6127     * An empty ("") source string will return the empty string.
6128     * A {@code null} search string will return the source string.</p>
6129     *
6130     * <pre>
6131     * StringUtils.removeStartIgnoreCase(null, *)      = null
6132     * StringUtils.removeStartIgnoreCase("", *)        = ""
6133     * StringUtils.removeStartIgnoreCase(*, null)      = *
6134     * StringUtils.removeStartIgnoreCase("www.domain.com", "www.")   = "domain.com"
6135     * StringUtils.removeStartIgnoreCase("www.domain.com", "WWW.")   = "domain.com"
6136     * StringUtils.removeStartIgnoreCase("domain.com", "www.")       = "domain.com"
6137     * StringUtils.removeStartIgnoreCase("www.domain.com", "domain") = "www.domain.com"
6138     * StringUtils.removeStartIgnoreCase("abc", "")    = "abc"
6139     * </pre>
6140     *
6141     * @param str  the source String to search, may be null
6142     * @param remove  the String to search for (case-insensitive) and remove, may be null
6143     * @return the substring with the string removed if found,
6144     *  {@code null} if null String input
6145     * @since 2.4
6146     */
6147    public static String removeStartIgnoreCase(final String str, final String remove) {
6148        if (str != null && startsWithIgnoreCase(str, remove)) {
6149            return str.substring(length(remove));
6150        }
6151        return str;
6152    }
6153
6154    /**
6155     * Returns padding using the specified delimiter repeated
6156     * to a given length.
6157     *
6158     * <pre>
6159     * StringUtils.repeat('e', 0)  = ""
6160     * StringUtils.repeat('e', 3)  = "eee"
6161     * StringUtils.repeat('e', -2) = ""
6162     * </pre>
6163     *
6164     * <p>Note: this method does not support padding with
6165     * <a href="https://www.unicode.org/glossary/#supplementary_character">Unicode Supplementary Characters</a>
6166     * as they require a pair of {@code char}s to be represented.
6167     * If you are needing to support full I18N of your applications
6168     * consider using {@link #repeat(String, int)} instead.
6169     * </p>
6170     *
6171     * @param ch  character to repeat
6172     * @param repeat  number of times to repeat char, negative treated as zero
6173     * @return String with repeated character
6174     * @see #repeat(String, int)
6175     */
6176    public static String repeat(final char ch, final int repeat) {
6177        if (repeat <= 0) {
6178            return EMPTY;
6179        }
6180        final char[] buf = new char[repeat];
6181        Arrays.fill(buf, ch);
6182        return new String(buf);
6183    }
6184
6185    /**
6186     * Repeat a String {@code repeat} times to form a
6187     * new String.
6188     *
6189     * <pre>
6190     * StringUtils.repeat(null, 2) = null
6191     * StringUtils.repeat("", 0)   = ""
6192     * StringUtils.repeat("", 2)   = ""
6193     * StringUtils.repeat("a", 3)  = "aaa"
6194     * StringUtils.repeat("ab", 2) = "abab"
6195     * StringUtils.repeat("a", -2) = ""
6196     * </pre>
6197     *
6198     * @param str  the String to repeat, may be null
6199     * @param repeat  number of times to repeat str, negative treated as zero
6200     * @return a new String consisting of the original String repeated,
6201     *  {@code null} if null String input
6202     */
6203    public static String repeat(final String str, final int repeat) {
6204        // Performance tuned for 2.0 (JDK1.4)
6205        if (str == null) {
6206            return null;
6207        }
6208        if (repeat <= 0) {
6209            return EMPTY;
6210        }
6211        final int inputLength = str.length();
6212        if (repeat == 1 || inputLength == 0) {
6213            return str;
6214        }
6215        if (inputLength == 1 && repeat <= PAD_LIMIT) {
6216            return repeat(str.charAt(0), repeat);
6217        }
6218
6219        final int outputLength = inputLength * repeat;
6220        switch (inputLength) {
6221            case 1 :
6222                return repeat(str.charAt(0), repeat);
6223            case 2 :
6224                final char ch0 = str.charAt(0);
6225                final char ch1 = str.charAt(1);
6226                final char[] output2 = new char[outputLength];
6227                for (int i = repeat * 2 - 2; i >= 0; i--, i--) {
6228                    output2[i] = ch0;
6229                    output2[i + 1] = ch1;
6230                }
6231                return new String(output2);
6232            default :
6233                final StringBuilder buf = new StringBuilder(outputLength);
6234                for (int i = 0; i < repeat; i++) {
6235                    buf.append(str);
6236                }
6237                return buf.toString();
6238        }
6239    }
6240
6241    /**
6242     * Repeat a String {@code repeat} times to form a
6243     * new String, with a String separator injected each time.
6244     *
6245     * <pre>
6246     * StringUtils.repeat(null, null, 2) = null
6247     * StringUtils.repeat(null, "x", 2)  = null
6248     * StringUtils.repeat("", null, 0)   = ""
6249     * StringUtils.repeat("", "", 2)     = ""
6250     * StringUtils.repeat("", "x", 3)    = "xx"
6251     * StringUtils.repeat("?", ", ", 3)  = "?, ?, ?"
6252     * </pre>
6253     *
6254     * @param str        the String to repeat, may be null
6255     * @param separator  the String to inject, may be null
6256     * @param repeat     number of times to repeat str, negative treated as zero
6257     * @return a new String consisting of the original String repeated,
6258     *  {@code null} if null String input
6259     * @since 2.5
6260     */
6261    public static String repeat(final String str, final String separator, final int repeat) {
6262        if (str == null || separator == null) {
6263            return repeat(str, repeat);
6264        }
6265        // given that repeat(String, int) is quite optimized, better to rely on it than try and splice this into it
6266        final String result = repeat(str + separator, repeat);
6267        return removeEnd(result, separator);
6268    }
6269
6270    /**
6271     * Replaces all occurrences of a String within another String.
6272     *
6273     * <p>A {@code null} reference passed to this method is a no-op.</p>
6274     *
6275     * <pre>
6276     * StringUtils.replace(null, *, *)        = null
6277     * StringUtils.replace("", *, *)          = ""
6278     * StringUtils.replace("any", null, *)    = "any"
6279     * StringUtils.replace("any", *, null)    = "any"
6280     * StringUtils.replace("any", "", *)      = "any"
6281     * StringUtils.replace("aba", "a", null)  = "aba"
6282     * StringUtils.replace("aba", "a", "")    = "b"
6283     * StringUtils.replace("aba", "a", "z")   = "zbz"
6284     * </pre>
6285     *
6286     * @see #replace(String text, String searchString, String replacement, int max)
6287     * @param text  text to search and replace in, may be null
6288     * @param searchString  the String to search for, may be null
6289     * @param replacement  the String to replace it with, may be null
6290     * @return the text with any replacements processed,
6291     *  {@code null} if null String input
6292     */
6293    public static String replace(final String text, final String searchString, final String replacement) {
6294        return replace(text, searchString, replacement, -1);
6295    }
6296
6297    /**
6298     * Replaces a String with another String inside a larger String,
6299     * for the first {@code max} values of the search String.
6300     *
6301     * <p>A {@code null} reference passed to this method is a no-op.</p>
6302     *
6303     * <pre>
6304     * StringUtils.replace(null, *, *, *)         = null
6305     * StringUtils.replace("", *, *, *)           = ""
6306     * StringUtils.replace("any", null, *, *)     = "any"
6307     * StringUtils.replace("any", *, null, *)     = "any"
6308     * StringUtils.replace("any", "", *, *)       = "any"
6309     * StringUtils.replace("any", *, *, 0)        = "any"
6310     * StringUtils.replace("abaa", "a", null, -1) = "abaa"
6311     * StringUtils.replace("abaa", "a", "", -1)   = "b"
6312     * StringUtils.replace("abaa", "a", "z", 0)   = "abaa"
6313     * StringUtils.replace("abaa", "a", "z", 1)   = "zbaa"
6314     * StringUtils.replace("abaa", "a", "z", 2)   = "zbza"
6315     * StringUtils.replace("abaa", "a", "z", -1)  = "zbzz"
6316     * </pre>
6317     *
6318     * @param text  text to search and replace in, may be null
6319     * @param searchString  the String to search for, may be null
6320     * @param replacement  the String to replace it with, may be null
6321     * @param max  maximum number of values to replace, or {@code -1} if no maximum
6322     * @return the text with any replacements processed,
6323     *  {@code null} if null String input
6324     */
6325    public static String replace(final String text, final String searchString, final String replacement, final int max) {
6326        return replace(text, searchString, replacement, max, false);
6327    }
6328
6329    /**
6330     * Replaces a String with another String inside a larger String,
6331     * for the first {@code max} values of the search String,
6332     * case-sensitively/insensitively based on {@code ignoreCase} value.
6333     *
6334     * <p>A {@code null} reference passed to this method is a no-op.</p>
6335     *
6336     * <pre>
6337     * StringUtils.replace(null, *, *, *, false)         = null
6338     * StringUtils.replace("", *, *, *, false)           = ""
6339     * StringUtils.replace("any", null, *, *, false)     = "any"
6340     * StringUtils.replace("any", *, null, *, false)     = "any"
6341     * StringUtils.replace("any", "", *, *, false)       = "any"
6342     * StringUtils.replace("any", *, *, 0, false)        = "any"
6343     * StringUtils.replace("abaa", "a", null, -1, false) = "abaa"
6344     * StringUtils.replace("abaa", "a", "", -1, false)   = "b"
6345     * StringUtils.replace("abaa", "a", "z", 0, false)   = "abaa"
6346     * StringUtils.replace("abaa", "A", "z", 1, false)   = "abaa"
6347     * StringUtils.replace("abaa", "A", "z", 1, true)   = "zbaa"
6348     * StringUtils.replace("abAa", "a", "z", 2, true)   = "zbza"
6349     * StringUtils.replace("abAa", "a", "z", -1, true)  = "zbzz"
6350     * </pre>
6351     *
6352     * @param text  text to search and replace in, may be null
6353     * @param searchString  the String to search for (case-insensitive), may be null
6354     * @param replacement  the String to replace it with, may be null
6355     * @param max  maximum number of values to replace, or {@code -1} if no maximum
6356     * @param ignoreCase if true replace is case-insensitive, otherwise case-sensitive
6357     * @return the text with any replacements processed,
6358     *  {@code null} if null String input
6359     */
6360     private static String replace(final String text, String searchString, final String replacement, int max, final boolean ignoreCase) {
6361         if (isEmpty(text) || isEmpty(searchString) || replacement == null || max == 0) {
6362             return text;
6363         }
6364         if (ignoreCase) {
6365             searchString = searchString.toLowerCase();
6366         }
6367         int start = 0;
6368         int end = ignoreCase ? indexOfIgnoreCase(text, searchString, start) : indexOf(text, searchString, start);
6369         if (end == INDEX_NOT_FOUND) {
6370             return text;
6371         }
6372         final int replLength = searchString.length();
6373         int increase = Math.max(replacement.length() - replLength, 0);
6374         increase *= max < 0 ? 16 : Math.min(max, 64);
6375         final StringBuilder buf = new StringBuilder(text.length() + increase);
6376         while (end != INDEX_NOT_FOUND) {
6377             buf.append(text, start, end).append(replacement);
6378             start = end + replLength;
6379             if (--max == 0) {
6380                 break;
6381             }
6382             end = ignoreCase ? indexOfIgnoreCase(text, searchString, start) : indexOf(text, searchString, start);
6383         }
6384         buf.append(text, start, text.length());
6385         return buf.toString();
6386     }
6387
6388    /**
6389     * Replaces each substring of the text String that matches the given regular expression
6390     * with the given replacement.
6391     *
6392     * This method is a {@code null} safe equivalent to:
6393     * <ul>
6394     *  <li>{@code text.replaceAll(regex, replacement)}</li>
6395     *  <li>{@code Pattern.compile(regex).matcher(text).replaceAll(replacement)}</li>
6396     * </ul>
6397     *
6398     * <p>A {@code null} reference passed to this method is a no-op.</p>
6399     *
6400     * <p>Unlike in the {@link #replacePattern(String, String, String)} method, the {@link Pattern#DOTALL} option
6401     * is NOT automatically added.
6402     * To use the DOTALL option prepend {@code "(?s)"} to the regex.
6403     * DOTALL is also known as single-line mode in Perl.</p>
6404     *
6405     * <pre>
6406     * StringUtils.replaceAll(null, *, *)       = null
6407     * StringUtils.replaceAll("any", (String) null, *)   = "any"
6408     * StringUtils.replaceAll("any", *, null)   = "any"
6409     * StringUtils.replaceAll("", "", "zzz")    = "zzz"
6410     * StringUtils.replaceAll("", ".*", "zzz")  = "zzz"
6411     * StringUtils.replaceAll("", ".+", "zzz")  = ""
6412     * StringUtils.replaceAll("abc", "", "ZZ")  = "ZZaZZbZZcZZ"
6413     * StringUtils.replaceAll("&lt;__&gt;\n&lt;__&gt;", "&lt;.*&gt;", "z")      = "z\nz"
6414     * StringUtils.replaceAll("&lt;__&gt;\n&lt;__&gt;", "(?s)&lt;.*&gt;", "z")  = "z"
6415     * StringUtils.replaceAll("ABCabc123", "[a-z]", "_")       = "ABC___123"
6416     * StringUtils.replaceAll("ABCabc123", "[^A-Z0-9]+", "_")  = "ABC_123"
6417     * StringUtils.replaceAll("ABCabc123", "[^A-Z0-9]+", "")   = "ABC123"
6418     * StringUtils.replaceAll("Lorem ipsum  dolor   sit", "( +)([a-z]+)", "_$2")  = "Lorem_ipsum_dolor_sit"
6419     * </pre>
6420     *
6421     * @param text  text to search and replace in, may be null
6422     * @param regex  the regular expression to which this string is to be matched
6423     * @param replacement  the string to be substituted for each match
6424     * @return  the text with any replacements processed,
6425     *              {@code null} if null String input
6426     *
6427     * @throws  java.util.regex.PatternSyntaxException
6428     *              if the regular expression's syntax is invalid
6429     *
6430     * @see #replacePattern(String, String, String)
6431     * @see String#replaceAll(String, String)
6432     * @see java.util.regex.Pattern
6433     * @see java.util.regex.Pattern#DOTALL
6434     * @since 3.5
6435     *
6436     * @deprecated Moved to RegExUtils.
6437     */
6438    @Deprecated
6439    public static String replaceAll(final String text, final String regex, final String replacement) {
6440        return RegExUtils.replaceAll(text, regex, replacement);
6441    }
6442
6443    /**
6444     * Replaces all occurrences of a character in a String with another.
6445     * This is a null-safe version of {@link String#replace(char, char)}.
6446     *
6447     * <p>A {@code null} string input returns {@code null}.
6448     * An empty ("") string input returns an empty string.</p>
6449     *
6450     * <pre>
6451     * StringUtils.replaceChars(null, *, *)        = null
6452     * StringUtils.replaceChars("", *, *)          = ""
6453     * StringUtils.replaceChars("abcba", 'b', 'y') = "aycya"
6454     * StringUtils.replaceChars("abcba", 'z', 'y') = "abcba"
6455     * </pre>
6456     *
6457     * @param str  String to replace characters in, may be null
6458     * @param searchChar  the character to search for, may be null
6459     * @param replaceChar  the character to replace, may be null
6460     * @return modified String, {@code null} if null string input
6461     * @since 2.0
6462     */
6463    public static String replaceChars(final String str, final char searchChar, final char replaceChar) {
6464        if (str == null) {
6465            return null;
6466        }
6467        return str.replace(searchChar, replaceChar);
6468    }
6469
6470    /**
6471     * Replaces multiple characters in a String in one go.
6472     * This method can also be used to delete characters.
6473     *
6474     * <p>For example:<br>
6475     * {@code replaceChars(&quot;hello&quot;, &quot;ho&quot;, &quot;jy&quot;) = jelly}.</p>
6476     *
6477     * <p>A {@code null} string input returns {@code null}.
6478     * An empty ("") string input returns an empty string.
6479     * A null or empty set of search characters returns the input string.</p>
6480     *
6481     * <p>The length of the search characters should normally equal the length
6482     * of the replace characters.
6483     * If the search characters is longer, then the extra search characters
6484     * are deleted.
6485     * If the search characters is shorter, then the extra replace characters
6486     * are ignored.</p>
6487     *
6488     * <pre>
6489     * StringUtils.replaceChars(null, *, *)           = null
6490     * StringUtils.replaceChars("", *, *)             = ""
6491     * StringUtils.replaceChars("abc", null, *)       = "abc"
6492     * StringUtils.replaceChars("abc", "", *)         = "abc"
6493     * StringUtils.replaceChars("abc", "b", null)     = "ac"
6494     * StringUtils.replaceChars("abc", "b", "")       = "ac"
6495     * StringUtils.replaceChars("abcba", "bc", "yz")  = "ayzya"
6496     * StringUtils.replaceChars("abcba", "bc", "y")   = "ayya"
6497     * StringUtils.replaceChars("abcba", "bc", "yzx") = "ayzya"
6498     * </pre>
6499     *
6500     * @param str  String to replace characters in, may be null
6501     * @param searchChars  a set of characters to search for, may be null
6502     * @param replaceChars  a set of characters to replace, may be null
6503     * @return modified String, {@code null} if null string input
6504     * @since 2.0
6505     */
6506    public static String replaceChars(final String str, final String searchChars, String replaceChars) {
6507        if (isEmpty(str) || isEmpty(searchChars)) {
6508            return str;
6509        }
6510        if (replaceChars == null) {
6511            replaceChars = EMPTY;
6512        }
6513        boolean modified = false;
6514        final int replaceCharsLength = replaceChars.length();
6515        final int strLength = str.length();
6516        final StringBuilder buf = new StringBuilder(strLength);
6517        for (int i = 0; i < strLength; i++) {
6518            final char ch = str.charAt(i);
6519            final int index = searchChars.indexOf(ch);
6520            if (index >= 0) {
6521                modified = true;
6522                if (index < replaceCharsLength) {
6523                    buf.append(replaceChars.charAt(index));
6524                }
6525            } else {
6526                buf.append(ch);
6527            }
6528        }
6529        if (modified) {
6530            return buf.toString();
6531        }
6532        return str;
6533    }
6534
6535    /**
6536     * Replaces all occurrences of Strings within another String.
6537     *
6538     * <p>
6539     * A {@code null} reference passed to this method is a no-op, or if
6540     * any "search string" or "string to replace" is null, that replace will be
6541     * ignored. This will not repeat. For repeating replaces, call the
6542     * overloaded method.
6543     * </p>
6544     *
6545     * <pre>
6546     *  StringUtils.replaceEach(null, *, *)        = null
6547     *  StringUtils.replaceEach("", *, *)          = ""
6548     *  StringUtils.replaceEach("aba", null, null) = "aba"
6549     *  StringUtils.replaceEach("aba", new String[0], null) = "aba"
6550     *  StringUtils.replaceEach("aba", null, new String[0]) = "aba"
6551     *  StringUtils.replaceEach("aba", new String[]{"a"}, null)  = "aba"
6552     *  StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""})  = "b"
6553     *  StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"})  = "aba"
6554     *  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"})  = "wcte"
6555     *  (example of how it does not repeat)
6556     *  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"})  = "dcte"
6557     * </pre>
6558     *
6559     * @param text
6560     *            text to search and replace in, no-op if null
6561     * @param searchList
6562     *            the Strings to search for, no-op if null
6563     * @param replacementList
6564     *            the Strings to replace them with, no-op if null
6565     * @return the text with any replacements processed, {@code null} if
6566     *         null String input
6567     * @throws IllegalArgumentException
6568     *             if the lengths of the arrays are not the same (null is ok,
6569     *             and/or size 0)
6570     * @since 2.4
6571     */
6572    public static String replaceEach(final String text, final String[] searchList, final String[] replacementList) {
6573        return replaceEach(text, searchList, replacementList, false, 0);
6574    }
6575
6576    /**
6577     * Replace all occurrences of Strings within another String.
6578     * This is a private recursive helper method for {@link #replaceEachRepeatedly(String, String[], String[])} and
6579     * {@link #replaceEach(String, String[], String[])}
6580     *
6581     * <p>
6582     * A {@code null} reference passed to this method is a no-op, or if
6583     * any "search string" or "string to replace" is null, that replace will be
6584     * ignored.
6585     * </p>
6586     *
6587     * <pre>
6588     *  StringUtils.replaceEach(null, *, *, *, *) = null
6589     *  StringUtils.replaceEach("", *, *, *, *) = ""
6590     *  StringUtils.replaceEach("aba", null, null, *, *) = "aba"
6591     *  StringUtils.replaceEach("aba", new String[0], null, *, *) = "aba"
6592     *  StringUtils.replaceEach("aba", null, new String[0], *, *) = "aba"
6593     *  StringUtils.replaceEach("aba", new String[]{"a"}, null, *, *) = "aba"
6594     *  StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""}, *, >=0) = "b"
6595     *  StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"}, *, >=0) = "aba"
6596     *  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"}, *, >=0) = "wcte"
6597     *  (example of how it repeats)
6598     *  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, false, >=0) = "dcte"
6599     *  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, true, >=2) = "tcte"
6600     *  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, *, *) = IllegalStateException
6601     * </pre>
6602     *
6603     * @param text
6604     *            text to search and replace in, no-op if null
6605     * @param searchList
6606     *            the Strings to search for, no-op if null
6607     * @param replacementList
6608     *            the Strings to replace them with, no-op if null
6609     * @param repeat if true, then replace repeatedly
6610     *       until there are no more possible replacements or timeToLive < 0
6611     * @param timeToLive
6612     *            if less than 0 then there is a circular reference and endless
6613     *            loop
6614     * @return the text with any replacements processed, {@code null} if
6615     *         null String input
6616     * @throws IllegalStateException
6617     *             if the search is repeating and there is an endless loop due
6618     *             to outputs of one being inputs to another
6619     * @throws IllegalArgumentException
6620     *             if the lengths of the arrays are not the same (null is ok,
6621     *             and/or size 0)
6622     * @since 2.4
6623     */
6624    private static String replaceEach(
6625            final String text, final String[] searchList, final String[] replacementList, final boolean repeat, final int timeToLive) {
6626
6627        // mchyzer Performance note: This creates very few new objects (one major goal)
6628        // let me know if there are performance requests, we can create a harness to measure
6629
6630        // if recursing, this shouldn't be less than 0
6631        if (timeToLive < 0) {
6632            final Set<String> searchSet = new HashSet<>(Arrays.asList(searchList));
6633            final Set<String> replacementSet = new HashSet<>(Arrays.asList(replacementList));
6634            searchSet.retainAll(replacementSet);
6635            if (!searchSet.isEmpty()) {
6636                throw new IllegalStateException("Aborting to protect against StackOverflowError - " +
6637                        "output of one loop is the input of another");
6638            }
6639        }
6640
6641        if (isEmpty(text) || ArrayUtils.isEmpty(searchList) || ArrayUtils.isEmpty(replacementList) || ArrayUtils.isNotEmpty(searchList) && timeToLive == -1) {
6642            return text;
6643        }
6644
6645        final int searchLength = searchList.length;
6646        final int replacementLength = replacementList.length;
6647
6648        // make sure lengths are ok, these need to be equal
6649        if (searchLength != replacementLength) {
6650            throw new IllegalArgumentException("Search and Replace array lengths don't match: "
6651                + searchLength
6652                + " vs "
6653                + replacementLength);
6654        }
6655
6656        // keep track of which still have matches
6657        final boolean[] noMoreMatchesForReplIndex = new boolean[searchLength];
6658
6659        // index on index that the match was found
6660        int textIndex = -1;
6661        int replaceIndex = -1;
6662        int tempIndex;
6663
6664        // index of replace array that will replace the search string found
6665        // NOTE: logic duplicated below START
6666        for (int i = 0; i < searchLength; i++) {
6667            if (noMoreMatchesForReplIndex[i] || isEmpty(searchList[i]) || replacementList[i] == null) {
6668                continue;
6669            }
6670            tempIndex = text.indexOf(searchList[i]);
6671
6672            // see if we need to keep searching for this
6673            if (tempIndex == -1) {
6674                noMoreMatchesForReplIndex[i] = true;
6675            } else if (textIndex == -1 || tempIndex < textIndex) {
6676                textIndex = tempIndex;
6677                replaceIndex = i;
6678            }
6679        }
6680        // NOTE: logic mostly below END
6681
6682        // no search strings found, we are done
6683        if (textIndex == -1) {
6684            return text;
6685        }
6686
6687        int start = 0;
6688
6689        // get a good guess on the size of the result buffer so it doesn't have to double if it goes over a bit
6690        int increase = 0;
6691
6692        // count the replacement text elements that are larger than their corresponding text being replaced
6693        for (int i = 0; i < searchList.length; i++) {
6694            if (searchList[i] == null || replacementList[i] == null) {
6695                continue;
6696            }
6697            final int greater = replacementList[i].length() - searchList[i].length();
6698            if (greater > 0) {
6699                increase += 3 * greater; // assume 3 matches
6700            }
6701        }
6702        // have upper-bound at 20% increase, then let Java take over
6703        increase = Math.min(increase, text.length() / 5);
6704
6705        final StringBuilder buf = new StringBuilder(text.length() + increase);
6706
6707        while (textIndex != -1) {
6708
6709            for (int i = start; i < textIndex; i++) {
6710                buf.append(text.charAt(i));
6711            }
6712            buf.append(replacementList[replaceIndex]);
6713
6714            start = textIndex + searchList[replaceIndex].length();
6715
6716            textIndex = -1;
6717            replaceIndex = -1;
6718            // find the next earliest match
6719            // NOTE: logic mostly duplicated above START
6720            for (int i = 0; i < searchLength; i++) {
6721                if (noMoreMatchesForReplIndex[i] || isEmpty(searchList[i]) || replacementList[i] == null) {
6722                    continue;
6723                }
6724                tempIndex = text.indexOf(searchList[i], start);
6725
6726                // see if we need to keep searching for this
6727                if (tempIndex == -1) {
6728                    noMoreMatchesForReplIndex[i] = true;
6729                } else if (textIndex == -1 || tempIndex < textIndex) {
6730                    textIndex = tempIndex;
6731                    replaceIndex = i;
6732                }
6733            }
6734            // NOTE: logic duplicated above END
6735
6736        }
6737        final int textLength = text.length();
6738        for (int i = start; i < textLength; i++) {
6739            buf.append(text.charAt(i));
6740        }
6741        final String result = buf.toString();
6742        if (!repeat) {
6743            return result;
6744        }
6745
6746        return replaceEach(result, searchList, replacementList, repeat, timeToLive - 1);
6747    }
6748
6749    /**
6750     * Replaces all occurrences of Strings within another String.
6751     *
6752     * <p>
6753     * A {@code null} reference passed to this method is a no-op, or if
6754     * any "search string" or "string to replace" is null, that replace will be
6755     * ignored.
6756     * </p>
6757     *
6758     * <pre>
6759     *  StringUtils.replaceEachRepeatedly(null, *, *) = null
6760     *  StringUtils.replaceEachRepeatedly("", *, *) = ""
6761     *  StringUtils.replaceEachRepeatedly("aba", null, null) = "aba"
6762     *  StringUtils.replaceEachRepeatedly("aba", new String[0], null) = "aba"
6763     *  StringUtils.replaceEachRepeatedly("aba", null, new String[0]) = "aba"
6764     *  StringUtils.replaceEachRepeatedly("aba", new String[]{"a"}, null) = "aba"
6765     *  StringUtils.replaceEachRepeatedly("aba", new String[]{"a"}, new String[]{""}) = "b"
6766     *  StringUtils.replaceEachRepeatedly("aba", new String[]{null}, new String[]{"a"}) = "aba"
6767     *  StringUtils.replaceEachRepeatedly("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"}) = "wcte"
6768     *  (example of how it repeats)
6769     *  StringUtils.replaceEachRepeatedly("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}) = "tcte"
6770     *  StringUtils.replaceEachRepeatedly("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}) = IllegalStateException
6771     * </pre>
6772     *
6773     * @param text
6774     *            text to search and replace in, no-op if null
6775     * @param searchList
6776     *            the Strings to search for, no-op if null
6777     * @param replacementList
6778     *            the Strings to replace them with, no-op if null
6779     * @return the text with any replacements processed, {@code null} if
6780     *         null String input
6781     * @throws IllegalStateException
6782     *             if the search is repeating and there is an endless loop due
6783     *             to outputs of one being inputs to another
6784     * @throws IllegalArgumentException
6785     *             if the lengths of the arrays are not the same (null is ok,
6786     *             and/or size 0)
6787     * @since 2.4
6788     */
6789    public static String replaceEachRepeatedly(final String text, final String[] searchList, final String[] replacementList) {
6790        return replaceEach(text, searchList, replacementList, true, ArrayUtils.getLength(searchList));
6791    }
6792
6793    /**
6794     * Replaces the first substring of the text string that matches the given regular expression
6795     * with the given replacement.
6796     *
6797     * This method is a {@code null} safe equivalent to:
6798     * <ul>
6799     *  <li>{@code text.replaceFirst(regex, replacement)}</li>
6800     *  <li>{@code Pattern.compile(regex).matcher(text).replaceFirst(replacement)}</li>
6801     * </ul>
6802     *
6803     * <p>A {@code null} reference passed to this method is a no-op.</p>
6804     *
6805     * <p>The {@link Pattern#DOTALL} option is NOT automatically added.
6806     * To use the DOTALL option prepend {@code "(?s)"} to the regex.
6807     * DOTALL is also known as single-line mode in Perl.</p>
6808     *
6809     * <pre>
6810     * StringUtils.replaceFirst(null, *, *)       = null
6811     * StringUtils.replaceFirst("any", (String) null, *)   = "any"
6812     * StringUtils.replaceFirst("any", *, null)   = "any"
6813     * StringUtils.replaceFirst("", "", "zzz")    = "zzz"
6814     * StringUtils.replaceFirst("", ".*", "zzz")  = "zzz"
6815     * StringUtils.replaceFirst("", ".+", "zzz")  = ""
6816     * StringUtils.replaceFirst("abc", "", "ZZ")  = "ZZabc"
6817     * StringUtils.replaceFirst("&lt;__&gt;\n&lt;__&gt;", "&lt;.*&gt;", "z")      = "z\n&lt;__&gt;"
6818     * StringUtils.replaceFirst("&lt;__&gt;\n&lt;__&gt;", "(?s)&lt;.*&gt;", "z")  = "z"
6819     * StringUtils.replaceFirst("ABCabc123", "[a-z]", "_")          = "ABC_bc123"
6820     * StringUtils.replaceFirst("ABCabc123abc", "[^A-Z0-9]+", "_")  = "ABC_123abc"
6821     * StringUtils.replaceFirst("ABCabc123abc", "[^A-Z0-9]+", "")   = "ABC123abc"
6822     * StringUtils.replaceFirst("Lorem ipsum  dolor   sit", "( +)([a-z]+)", "_$2")  = "Lorem_ipsum  dolor   sit"
6823     * </pre>
6824     *
6825     * @param text  text to search and replace in, may be null
6826     * @param regex  the regular expression to which this string is to be matched
6827     * @param replacement  the string to be substituted for the first match
6828     * @return  the text with the first replacement processed,
6829     *              {@code null} if null String input
6830     *
6831     * @throws  java.util.regex.PatternSyntaxException
6832     *              if the regular expression's syntax is invalid
6833     *
6834     * @see String#replaceFirst(String, String)
6835     * @see java.util.regex.Pattern
6836     * @see java.util.regex.Pattern#DOTALL
6837     * @since 3.5
6838     *
6839     * @deprecated Moved to RegExUtils.
6840     */
6841    @Deprecated
6842    public static String replaceFirst(final String text, final String regex, final String replacement) {
6843        return RegExUtils.replaceFirst(text, regex, replacement);
6844    }
6845
6846    /**
6847     * Case insensitively replaces all occurrences of a String within another String.
6848     *
6849     * <p>A {@code null} reference passed to this method is a no-op.</p>
6850     *
6851     * <pre>
6852     * StringUtils.replaceIgnoreCase(null, *, *)        = null
6853     * StringUtils.replaceIgnoreCase("", *, *)          = ""
6854     * StringUtils.replaceIgnoreCase("any", null, *)    = "any"
6855     * StringUtils.replaceIgnoreCase("any", *, null)    = "any"
6856     * StringUtils.replaceIgnoreCase("any", "", *)      = "any"
6857     * StringUtils.replaceIgnoreCase("aba", "a", null)  = "aba"
6858     * StringUtils.replaceIgnoreCase("abA", "A", "")    = "b"
6859     * StringUtils.replaceIgnoreCase("aba", "A", "z")   = "zbz"
6860     * </pre>
6861     *
6862     * @see #replaceIgnoreCase(String text, String searchString, String replacement, int max)
6863     * @param text  text to search and replace in, may be null
6864     * @param searchString  the String to search for (case-insensitive), may be null
6865     * @param replacement  the String to replace it with, may be null
6866     * @return the text with any replacements processed,
6867     *  {@code null} if null String input
6868     * @since 3.5
6869     */
6870     public static String replaceIgnoreCase(final String text, final String searchString, final String replacement) {
6871         return replaceIgnoreCase(text, searchString, replacement, -1);
6872     }
6873
6874    /**
6875     * Case insensitively replaces a String with another String inside a larger String,
6876     * for the first {@code max} values of the search String.
6877     *
6878     * <p>A {@code null} reference passed to this method is a no-op.</p>
6879     *
6880     * <pre>
6881     * StringUtils.replaceIgnoreCase(null, *, *, *)         = null
6882     * StringUtils.replaceIgnoreCase("", *, *, *)           = ""
6883     * StringUtils.replaceIgnoreCase("any", null, *, *)     = "any"
6884     * StringUtils.replaceIgnoreCase("any", *, null, *)     = "any"
6885     * StringUtils.replaceIgnoreCase("any", "", *, *)       = "any"
6886     * StringUtils.replaceIgnoreCase("any", *, *, 0)        = "any"
6887     * StringUtils.replaceIgnoreCase("abaa", "a", null, -1) = "abaa"
6888     * StringUtils.replaceIgnoreCase("abaa", "a", "", -1)   = "b"
6889     * StringUtils.replaceIgnoreCase("abaa", "a", "z", 0)   = "abaa"
6890     * StringUtils.replaceIgnoreCase("abaa", "A", "z", 1)   = "zbaa"
6891     * StringUtils.replaceIgnoreCase("abAa", "a", "z", 2)   = "zbza"
6892     * StringUtils.replaceIgnoreCase("abAa", "a", "z", -1)  = "zbzz"
6893     * </pre>
6894     *
6895     * @param text  text to search and replace in, may be null
6896     * @param searchString  the String to search for (case-insensitive), may be null
6897     * @param replacement  the String to replace it with, may be null
6898     * @param max  maximum number of values to replace, or {@code -1} if no maximum
6899     * @return the text with any replacements processed,
6900     *  {@code null} if null String input
6901     * @since 3.5
6902     */
6903    public static String replaceIgnoreCase(final String text, final String searchString, final String replacement, final int max) {
6904        return replace(text, searchString, replacement, max, true);
6905    }
6906
6907    /**
6908     * Replaces a String with another String inside a larger String, once.
6909     *
6910     * <p>A {@code null} reference passed to this method is a no-op.</p>
6911     *
6912     * <pre>
6913     * StringUtils.replaceOnce(null, *, *)        = null
6914     * StringUtils.replaceOnce("", *, *)          = ""
6915     * StringUtils.replaceOnce("any", null, *)    = "any"
6916     * StringUtils.replaceOnce("any", *, null)    = "any"
6917     * StringUtils.replaceOnce("any", "", *)      = "any"
6918     * StringUtils.replaceOnce("aba", "a", null)  = "aba"
6919     * StringUtils.replaceOnce("aba", "a", "")    = "ba"
6920     * StringUtils.replaceOnce("aba", "a", "z")   = "zba"
6921     * </pre>
6922     *
6923     * @see #replace(String text, String searchString, String replacement, int max)
6924     * @param text  text to search and replace in, may be null
6925     * @param searchString  the String to search for, may be null
6926     * @param replacement  the String to replace with, may be null
6927     * @return the text with any replacements processed,
6928     *  {@code null} if null String input
6929     */
6930    public static String replaceOnce(final String text, final String searchString, final String replacement) {
6931        return replace(text, searchString, replacement, 1);
6932    }
6933
6934    /**
6935     * Case insensitively replaces a String with another String inside a larger String, once.
6936     *
6937     * <p>A {@code null} reference passed to this method is a no-op.</p>
6938     *
6939     * <pre>
6940     * StringUtils.replaceOnceIgnoreCase(null, *, *)        = null
6941     * StringUtils.replaceOnceIgnoreCase("", *, *)          = ""
6942     * StringUtils.replaceOnceIgnoreCase("any", null, *)    = "any"
6943     * StringUtils.replaceOnceIgnoreCase("any", *, null)    = "any"
6944     * StringUtils.replaceOnceIgnoreCase("any", "", *)      = "any"
6945     * StringUtils.replaceOnceIgnoreCase("aba", "a", null)  = "aba"
6946     * StringUtils.replaceOnceIgnoreCase("aba", "a", "")    = "ba"
6947     * StringUtils.replaceOnceIgnoreCase("aba", "a", "z")   = "zba"
6948     * StringUtils.replaceOnceIgnoreCase("FoOFoofoo", "foo", "") = "Foofoo"
6949     * </pre>
6950     *
6951     * @see #replaceIgnoreCase(String text, String searchString, String replacement, int max)
6952     * @param text  text to search and replace in, may be null
6953     * @param searchString  the String to search for (case-insensitive), may be null
6954     * @param replacement  the String to replace with, may be null
6955     * @return the text with any replacements processed,
6956     *  {@code null} if null String input
6957     * @since 3.5
6958     */
6959    public static String replaceOnceIgnoreCase(final String text, final String searchString, final String replacement) {
6960        return replaceIgnoreCase(text, searchString, replacement, 1);
6961    }
6962
6963    /**
6964     * Replaces each substring of the source String that matches the given regular expression with the given
6965     * replacement using the {@link Pattern#DOTALL} option. DOTALL is also known as single-line mode in Perl.
6966     *
6967     * This call is a {@code null} safe equivalent to:
6968     * <ul>
6969     * <li>{@code source.replaceAll(&quot;(?s)&quot; + regex, replacement)}</li>
6970     * <li>{@code Pattern.compile(regex, Pattern.DOTALL).matcher(source).replaceAll(replacement)}</li>
6971     * </ul>
6972     *
6973     * <p>A {@code null} reference passed to this method is a no-op.</p>
6974     *
6975     * <pre>
6976     * StringUtils.replacePattern(null, *, *)       = null
6977     * StringUtils.replacePattern("any", (String) null, *)   = "any"
6978     * StringUtils.replacePattern("any", *, null)   = "any"
6979     * StringUtils.replacePattern("", "", "zzz")    = "zzz"
6980     * StringUtils.replacePattern("", ".*", "zzz")  = "zzz"
6981     * StringUtils.replacePattern("", ".+", "zzz")  = ""
6982     * StringUtils.replacePattern("&lt;__&gt;\n&lt;__&gt;", "&lt;.*&gt;", "z")       = "z"
6983     * StringUtils.replacePattern("ABCabc123", "[a-z]", "_")       = "ABC___123"
6984     * StringUtils.replacePattern("ABCabc123", "[^A-Z0-9]+", "_")  = "ABC_123"
6985     * StringUtils.replacePattern("ABCabc123", "[^A-Z0-9]+", "")   = "ABC123"
6986     * StringUtils.replacePattern("Lorem ipsum  dolor   sit", "( +)([a-z]+)", "_$2")  = "Lorem_ipsum_dolor_sit"
6987     * </pre>
6988     *
6989     * @param source
6990     *            the source string
6991     * @param regex
6992     *            the regular expression to which this string is to be matched
6993     * @param replacement
6994     *            the string to be substituted for each match
6995     * @return The resulting {@link String}
6996     * @see #replaceAll(String, String, String)
6997     * @see String#replaceAll(String, String)
6998     * @see Pattern#DOTALL
6999     * @since 3.2
7000     * @since 3.5 Changed {@code null} reference passed to this method is a no-op.
7001     *
7002     * @deprecated Moved to RegExUtils.
7003     */
7004    @Deprecated
7005    public static String replacePattern(final String source, final String regex, final String replacement) {
7006        return RegExUtils.replacePattern(source, regex, replacement);
7007    }
7008
7009    /**
7010     * Reverses a String as per {@link StringBuilder#reverse()}.
7011     *
7012     * <p>A {@code null} String returns {@code null}.</p>
7013     *
7014     * <pre>
7015     * StringUtils.reverse(null)  = null
7016     * StringUtils.reverse("")    = ""
7017     * StringUtils.reverse("bat") = "tab"
7018     * </pre>
7019     *
7020     * @param str  the String to reverse, may be null
7021     * @return the reversed String, {@code null} if null String input
7022     */
7023    public static String reverse(final String str) {
7024        if (str == null) {
7025            return null;
7026        }
7027        return new StringBuilder(str).reverse().toString();
7028    }
7029
7030    /**
7031     * Reverses a String that is delimited by a specific character.
7032     *
7033     * <p>The Strings between the delimiters are not reversed.
7034     * Thus java.lang.String becomes String.lang.java (if the delimiter
7035     * is {@code '.'}).</p>
7036     *
7037     * <pre>
7038     * StringUtils.reverseDelimited(null, *)      = null
7039     * StringUtils.reverseDelimited("", *)        = ""
7040     * StringUtils.reverseDelimited("a.b.c", 'x') = "a.b.c"
7041     * StringUtils.reverseDelimited("a.b.c", ".") = "c.b.a"
7042     * </pre>
7043     *
7044     * @param str  the String to reverse, may be null
7045     * @param separatorChar  the separator character to use
7046     * @return the reversed String, {@code null} if null String input
7047     * @since 2.0
7048     */
7049    public static String reverseDelimited(final String str, final char separatorChar) {
7050        if (str == null) {
7051            return null;
7052        }
7053        // could implement manually, but simple way is to reuse other,
7054        // probably slower, methods.
7055        final String[] strs = split(str, separatorChar);
7056        ArrayUtils.reverse(strs);
7057        return join(strs, separatorChar);
7058    }
7059
7060    /**
7061     * Gets the rightmost {@code len} characters of a String.
7062     *
7063     * <p>If {@code len} characters are not available, or the String
7064     * is {@code null}, the String will be returned without an
7065     * an exception. An empty String is returned if len is negative.</p>
7066     *
7067     * <pre>
7068     * StringUtils.right(null, *)    = null
7069     * StringUtils.right(*, -ve)     = ""
7070     * StringUtils.right("", *)      = ""
7071     * StringUtils.right("abc", 0)   = ""
7072     * StringUtils.right("abc", 2)   = "bc"
7073     * StringUtils.right("abc", 4)   = "abc"
7074     * </pre>
7075     *
7076     * @param str  the String to get the rightmost characters from, may be null
7077     * @param len  the length of the required String
7078     * @return the rightmost characters, {@code null} if null String input
7079     */
7080    public static String right(final String str, final int len) {
7081        if (str == null) {
7082            return null;
7083        }
7084        if (len < 0) {
7085            return EMPTY;
7086        }
7087        if (str.length() <= len) {
7088            return str;
7089        }
7090        return str.substring(str.length() - len);
7091    }
7092
7093    /**
7094     * Right pad a String with spaces (' ').
7095     *
7096     * <p>The String is padded to the size of {@code size}.</p>
7097     *
7098     * <pre>
7099     * StringUtils.rightPad(null, *)   = null
7100     * StringUtils.rightPad("", 3)     = "   "
7101     * StringUtils.rightPad("bat", 3)  = "bat"
7102     * StringUtils.rightPad("bat", 5)  = "bat  "
7103     * StringUtils.rightPad("bat", 1)  = "bat"
7104     * StringUtils.rightPad("bat", -1) = "bat"
7105     * </pre>
7106     *
7107     * @param str  the String to pad out, may be null
7108     * @param size  the size to pad to
7109     * @return right padded String or original String if no padding is necessary,
7110     *  {@code null} if null String input
7111     */
7112    public static String rightPad(final String str, final int size) {
7113        return rightPad(str, size, ' ');
7114    }
7115
7116    /**
7117     * Right pad a String with a specified character.
7118     *
7119     * <p>The String is padded to the size of {@code size}.</p>
7120     *
7121     * <pre>
7122     * StringUtils.rightPad(null, *, *)     = null
7123     * StringUtils.rightPad("", 3, 'z')     = "zzz"
7124     * StringUtils.rightPad("bat", 3, 'z')  = "bat"
7125     * StringUtils.rightPad("bat", 5, 'z')  = "batzz"
7126     * StringUtils.rightPad("bat", 1, 'z')  = "bat"
7127     * StringUtils.rightPad("bat", -1, 'z') = "bat"
7128     * </pre>
7129     *
7130     * @param str  the String to pad out, may be null
7131     * @param size  the size to pad to
7132     * @param padChar  the character to pad with
7133     * @return right padded String or original String if no padding is necessary,
7134     *  {@code null} if null String input
7135     * @since 2.0
7136     */
7137    public static String rightPad(final String str, final int size, final char padChar) {
7138        if (str == null) {
7139            return null;
7140        }
7141        final int pads = size - str.length();
7142        if (pads <= 0) {
7143            return str; // returns original String when possible
7144        }
7145        if (pads > PAD_LIMIT) {
7146            return rightPad(str, size, String.valueOf(padChar));
7147        }
7148        return str.concat(repeat(padChar, pads));
7149    }
7150
7151    /**
7152     * Right pad a String with a specified String.
7153     *
7154     * <p>The String is padded to the size of {@code size}.</p>
7155     *
7156     * <pre>
7157     * StringUtils.rightPad(null, *, *)      = null
7158     * StringUtils.rightPad("", 3, "z")      = "zzz"
7159     * StringUtils.rightPad("bat", 3, "yz")  = "bat"
7160     * StringUtils.rightPad("bat", 5, "yz")  = "batyz"
7161     * StringUtils.rightPad("bat", 8, "yz")  = "batyzyzy"
7162     * StringUtils.rightPad("bat", 1, "yz")  = "bat"
7163     * StringUtils.rightPad("bat", -1, "yz") = "bat"
7164     * StringUtils.rightPad("bat", 5, null)  = "bat  "
7165     * StringUtils.rightPad("bat", 5, "")    = "bat  "
7166     * </pre>
7167     *
7168     * @param str  the String to pad out, may be null
7169     * @param size  the size to pad to
7170     * @param padStr  the String to pad with, null or empty treated as single space
7171     * @return right padded String or original String if no padding is necessary,
7172     *  {@code null} if null String input
7173     */
7174    public static String rightPad(final String str, final int size, String padStr) {
7175        if (str == null) {
7176            return null;
7177        }
7178        if (isEmpty(padStr)) {
7179            padStr = SPACE;
7180        }
7181        final int padLen = padStr.length();
7182        final int strLen = str.length();
7183        final int pads = size - strLen;
7184        if (pads <= 0) {
7185            return str; // returns original String when possible
7186        }
7187        if (padLen == 1 && pads <= PAD_LIMIT) {
7188            return rightPad(str, size, padStr.charAt(0));
7189        }
7190
7191        if (pads == padLen) {
7192            return str.concat(padStr);
7193        }
7194        if (pads < padLen) {
7195            return str.concat(padStr.substring(0, pads));
7196        }
7197        final char[] padding = new char[pads];
7198        final char[] padChars = padStr.toCharArray();
7199        for (int i = 0; i < pads; i++) {
7200            padding[i] = padChars[i % padLen];
7201        }
7202        return str.concat(new String(padding));
7203    }
7204
7205    /**
7206     * Rotate (circular shift) a String of {@code shift} characters.
7207     * <ul>
7208     *  <li>If {@code shift > 0}, right circular shift (ex : ABCDEF =&gt; FABCDE)</li>
7209     *  <li>If {@code shift < 0}, left circular shift (ex : ABCDEF =&gt; BCDEFA)</li>
7210     * </ul>
7211     *
7212     * <pre>
7213     * StringUtils.rotate(null, *)        = null
7214     * StringUtils.rotate("", *)          = ""
7215     * StringUtils.rotate("abcdefg", 0)   = "abcdefg"
7216     * StringUtils.rotate("abcdefg", 2)   = "fgabcde"
7217     * StringUtils.rotate("abcdefg", -2)  = "cdefgab"
7218     * StringUtils.rotate("abcdefg", 7)   = "abcdefg"
7219     * StringUtils.rotate("abcdefg", -7)  = "abcdefg"
7220     * StringUtils.rotate("abcdefg", 9)   = "fgabcde"
7221     * StringUtils.rotate("abcdefg", -9)  = "cdefgab"
7222     * </pre>
7223     *
7224     * @param str  the String to rotate, may be null
7225     * @param shift  number of time to shift (positive : right shift, negative : left shift)
7226     * @return the rotated String,
7227     *          or the original String if {@code shift == 0},
7228     *          or {@code null} if null String input
7229     * @since 3.5
7230     */
7231    public static String rotate(final String str, final int shift) {
7232        if (str == null) {
7233            return null;
7234        }
7235
7236        final int strLen = str.length();
7237        if (shift == 0 || strLen == 0 || shift % strLen == 0) {
7238            return str;
7239        }
7240
7241        final StringBuilder builder = new StringBuilder(strLen);
7242        final int offset = - (shift % strLen);
7243        builder.append(substring(str, offset));
7244        builder.append(substring(str, 0, offset));
7245        return builder.toString();
7246    }
7247
7248    /**
7249     * Splits the provided text into an array, using whitespace as the
7250     * separator.
7251     * Whitespace is defined by {@link Character#isWhitespace(char)}.
7252     *
7253     * <p>The separator is not included in the returned String array.
7254     * Adjacent separators are treated as one separator.
7255     * For more control over the split use the StrTokenizer class.</p>
7256     *
7257     * <p>A {@code null} input String returns {@code null}.</p>
7258     *
7259     * <pre>
7260     * StringUtils.split(null)       = null
7261     * StringUtils.split("")         = []
7262     * StringUtils.split("abc def")  = ["abc", "def"]
7263     * StringUtils.split("abc  def") = ["abc", "def"]
7264     * StringUtils.split(" abc ")    = ["abc"]
7265     * </pre>
7266     *
7267     * @param str  the String to parse, may be null
7268     * @return an array of parsed Strings, {@code null} if null String input
7269     */
7270    public static String[] split(final String str) {
7271        return split(str, null, -1);
7272    }
7273
7274    /**
7275     * Splits the provided text into an array, separator specified.
7276     * This is an alternative to using StringTokenizer.
7277     *
7278     * <p>The separator is not included in the returned String array.
7279     * Adjacent separators are treated as one separator.
7280     * For more control over the split use the StrTokenizer class.</p>
7281     *
7282     * <p>A {@code null} input String returns {@code null}.</p>
7283     *
7284     * <pre>
7285     * StringUtils.split(null, *)         = null
7286     * StringUtils.split("", *)           = []
7287     * StringUtils.split("a.b.c", '.')    = ["a", "b", "c"]
7288     * StringUtils.split("a..b.c", '.')   = ["a", "b", "c"]
7289     * StringUtils.split("a:b:c", '.')    = ["a:b:c"]
7290     * StringUtils.split("a b c", ' ')    = ["a", "b", "c"]
7291     * </pre>
7292     *
7293     * @param str  the String to parse, may be null
7294     * @param separatorChar  the character used as the delimiter
7295     * @return an array of parsed Strings, {@code null} if null String input
7296     * @since 2.0
7297     */
7298    public static String[] split(final String str, final char separatorChar) {
7299        return splitWorker(str, separatorChar, false);
7300    }
7301
7302    /**
7303     * Splits the provided text into an array, separators specified.
7304     * This is an alternative to using StringTokenizer.
7305     *
7306     * <p>The separator is not included in the returned String array.
7307     * Adjacent separators are treated as one separator.
7308     * For more control over the split use the StrTokenizer class.</p>
7309     *
7310     * <p>A {@code null} input String returns {@code null}.
7311     * A {@code null} separatorChars splits on whitespace.</p>
7312     *
7313     * <pre>
7314     * StringUtils.split(null, *)         = null
7315     * StringUtils.split("", *)           = []
7316     * StringUtils.split("abc def", null) = ["abc", "def"]
7317     * StringUtils.split("abc def", " ")  = ["abc", "def"]
7318     * StringUtils.split("abc  def", " ") = ["abc", "def"]
7319     * StringUtils.split("ab:cd:ef", ":") = ["ab", "cd", "ef"]
7320     * </pre>
7321     *
7322     * @param str  the String to parse, may be null
7323     * @param separatorChars  the characters used as the delimiters,
7324     *  {@code null} splits on whitespace
7325     * @return an array of parsed Strings, {@code null} if null String input
7326     */
7327    public static String[] split(final String str, final String separatorChars) {
7328        return splitWorker(str, separatorChars, -1, false);
7329    }
7330
7331    /**
7332     * Splits the provided text into an array with a maximum length,
7333     * separators specified.
7334     *
7335     * <p>The separator is not included in the returned String array.
7336     * Adjacent separators are treated as one separator.</p>
7337     *
7338     * <p>A {@code null} input String returns {@code null}.
7339     * A {@code null} separatorChars splits on whitespace.</p>
7340     *
7341     * <p>If more than {@code max} delimited substrings are found, the last
7342     * returned string includes all characters after the first {@code max - 1}
7343     * returned strings (including separator characters).</p>
7344     *
7345     * <pre>
7346     * StringUtils.split(null, *, *)            = null
7347     * StringUtils.split("", *, *)              = []
7348     * StringUtils.split("ab cd ef", null, 0)   = ["ab", "cd", "ef"]
7349     * StringUtils.split("ab   cd ef", null, 0) = ["ab", "cd", "ef"]
7350     * StringUtils.split("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
7351     * StringUtils.split("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]
7352     * </pre>
7353     *
7354     * @param str  the String to parse, may be null
7355     * @param separatorChars  the characters used as the delimiters,
7356     *  {@code null} splits on whitespace
7357     * @param max  the maximum number of elements to include in the
7358     *  array. A zero or negative value implies no limit
7359     * @return an array of parsed Strings, {@code null} if null String input
7360     */
7361    public static String[] split(final String str, final String separatorChars, final int max) {
7362        return splitWorker(str, separatorChars, max, false);
7363    }
7364
7365    /**
7366     * Splits a String by Character type as returned by
7367     * {@code java.lang.Character.getType(char)}. Groups of contiguous
7368     * characters of the same type are returned as complete tokens.
7369     * <pre>
7370     * StringUtils.splitByCharacterType(null)         = null
7371     * StringUtils.splitByCharacterType("")           = []
7372     * StringUtils.splitByCharacterType("ab de fg")   = ["ab", " ", "de", " ", "fg"]
7373     * StringUtils.splitByCharacterType("ab   de fg") = ["ab", "   ", "de", " ", "fg"]
7374     * StringUtils.splitByCharacterType("ab:cd:ef")   = ["ab", ":", "cd", ":", "ef"]
7375     * StringUtils.splitByCharacterType("number5")    = ["number", "5"]
7376     * StringUtils.splitByCharacterType("fooBar")     = ["foo", "B", "ar"]
7377     * StringUtils.splitByCharacterType("foo200Bar")  = ["foo", "200", "B", "ar"]
7378     * StringUtils.splitByCharacterType("ASFRules")   = ["ASFR", "ules"]
7379     * </pre>
7380     * @param str the String to split, may be {@code null}
7381     * @return an array of parsed Strings, {@code null} if null String input
7382     * @since 2.4
7383     */
7384    public static String[] splitByCharacterType(final String str) {
7385        return splitByCharacterType(str, false);
7386    }
7387
7388    /**
7389     * <p>Splits a String by Character type as returned by
7390     * {@code java.lang.Character.getType(char)}. Groups of contiguous
7391     * characters of the same type are returned as complete tokens, with the
7392     * following exception: if {@code camelCase} is {@code true},
7393     * the character of type {@code Character.UPPERCASE_LETTER}, if any,
7394     * immediately preceding a token of type {@code Character.LOWERCASE_LETTER}
7395     * will belong to the following token rather than to the preceding, if any,
7396     * {@code Character.UPPERCASE_LETTER} token.
7397     * @param str the String to split, may be {@code null}
7398     * @param camelCase whether to use so-called "camel-case" for letter types
7399     * @return an array of parsed Strings, {@code null} if null String input
7400     * @since 2.4
7401     */
7402    private static String[] splitByCharacterType(final String str, final boolean camelCase) {
7403        if (str == null) {
7404            return null;
7405        }
7406        if (str.isEmpty()) {
7407            return ArrayUtils.EMPTY_STRING_ARRAY;
7408        }
7409        final char[] c = str.toCharArray();
7410        final List<String> list = new ArrayList<>();
7411        int tokenStart = 0;
7412        int currentType = Character.getType(c[tokenStart]);
7413        for (int pos = tokenStart + 1; pos < c.length; pos++) {
7414            final int type = Character.getType(c[pos]);
7415            if (type == currentType) {
7416                continue;
7417            }
7418            if (camelCase && type == Character.LOWERCASE_LETTER && currentType == Character.UPPERCASE_LETTER) {
7419                final int newTokenStart = pos - 1;
7420                if (newTokenStart != tokenStart) {
7421                    list.add(new String(c, tokenStart, newTokenStart - tokenStart));
7422                    tokenStart = newTokenStart;
7423                }
7424            } else {
7425                list.add(new String(c, tokenStart, pos - tokenStart));
7426                tokenStart = pos;
7427            }
7428            currentType = type;
7429        }
7430        list.add(new String(c, tokenStart, c.length - tokenStart));
7431        return list.toArray(ArrayUtils.EMPTY_STRING_ARRAY);
7432    }
7433
7434    /**
7435     * <p>Splits a String by Character type as returned by
7436     * {@code java.lang.Character.getType(char)}. Groups of contiguous
7437     * characters of the same type are returned as complete tokens, with the
7438     * following exception: the character of type
7439     * {@code Character.UPPERCASE_LETTER}, if any, immediately
7440     * preceding a token of type {@code Character.LOWERCASE_LETTER}
7441     * will belong to the following token rather than to the preceding, if any,
7442     * {@code Character.UPPERCASE_LETTER} token.
7443     * <pre>
7444     * StringUtils.splitByCharacterTypeCamelCase(null)         = null
7445     * StringUtils.splitByCharacterTypeCamelCase("")           = []
7446     * StringUtils.splitByCharacterTypeCamelCase("ab de fg")   = ["ab", " ", "de", " ", "fg"]
7447     * StringUtils.splitByCharacterTypeCamelCase("ab   de fg") = ["ab", "   ", "de", " ", "fg"]
7448     * StringUtils.splitByCharacterTypeCamelCase("ab:cd:ef")   = ["ab", ":", "cd", ":", "ef"]
7449     * StringUtils.splitByCharacterTypeCamelCase("number5")    = ["number", "5"]
7450     * StringUtils.splitByCharacterTypeCamelCase("fooBar")     = ["foo", "Bar"]
7451     * StringUtils.splitByCharacterTypeCamelCase("foo200Bar")  = ["foo", "200", "Bar"]
7452     * StringUtils.splitByCharacterTypeCamelCase("ASFRules")   = ["ASF", "Rules"]
7453     * </pre>
7454     * @param str the String to split, may be {@code null}
7455     * @return an array of parsed Strings, {@code null} if null String input
7456     * @since 2.4
7457     */
7458    public static String[] splitByCharacterTypeCamelCase(final String str) {
7459        return splitByCharacterType(str, true);
7460    }
7461
7462    /**
7463     * <p>Splits the provided text into an array, separator string specified.
7464     *
7465     * <p>The separator(s) will not be included in the returned String array.
7466     * Adjacent separators are treated as one separator.</p>
7467     *
7468     * <p>A {@code null} input String returns {@code null}.
7469     * A {@code null} separator splits on whitespace.</p>
7470     *
7471     * <pre>
7472     * StringUtils.splitByWholeSeparator(null, *)               = null
7473     * StringUtils.splitByWholeSeparator("", *)                 = []
7474     * StringUtils.splitByWholeSeparator("ab de fg", null)      = ["ab", "de", "fg"]
7475     * StringUtils.splitByWholeSeparator("ab   de fg", null)    = ["ab", "de", "fg"]
7476     * StringUtils.splitByWholeSeparator("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
7477     * StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]
7478     * </pre>
7479     *
7480     * @param str  the String to parse, may be null
7481     * @param separator  String containing the String to be used as a delimiter,
7482     *  {@code null} splits on whitespace
7483     * @return an array of parsed Strings, {@code null} if null String was input
7484     */
7485    public static String[] splitByWholeSeparator(final String str, final String separator) {
7486        return splitByWholeSeparatorWorker(str, separator, -1, false);
7487    }
7488
7489    /**
7490     * Splits the provided text into an array, separator string specified.
7491     * Returns a maximum of {@code max} substrings.
7492     *
7493     * <p>The separator(s) will not be included in the returned String array.
7494     * Adjacent separators are treated as one separator.</p>
7495     *
7496     * <p>A {@code null} input String returns {@code null}.
7497     * A {@code null} separator splits on whitespace.</p>
7498     *
7499     * <pre>
7500     * StringUtils.splitByWholeSeparator(null, *, *)               = null
7501     * StringUtils.splitByWholeSeparator("", *, *)                 = []
7502     * StringUtils.splitByWholeSeparator("ab de fg", null, 0)      = ["ab", "de", "fg"]
7503     * StringUtils.splitByWholeSeparator("ab   de fg", null, 0)    = ["ab", "de", "fg"]
7504     * StringUtils.splitByWholeSeparator("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
7505     * StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
7506     * StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]
7507     * </pre>
7508     *
7509     * @param str  the String to parse, may be null
7510     * @param separator  String containing the String to be used as a delimiter,
7511     *  {@code null} splits on whitespace
7512     * @param max  the maximum number of elements to include in the returned
7513     *  array. A zero or negative value implies no limit.
7514     * @return an array of parsed Strings, {@code null} if null String was input
7515     */
7516    public static String[] splitByWholeSeparator( final String str, final String separator, final int max) {
7517        return splitByWholeSeparatorWorker(str, separator, max, false);
7518    }
7519
7520    /**
7521     * Splits the provided text into an array, separator string specified.
7522     *
7523     * <p>The separator is not included in the returned String array.
7524     * Adjacent separators are treated as separators for empty tokens.
7525     * For more control over the split use the StrTokenizer class.</p>
7526     *
7527     * <p>A {@code null} input String returns {@code null}.
7528     * A {@code null} separator splits on whitespace.</p>
7529     *
7530     * <pre>
7531     * StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *)               = null
7532     * StringUtils.splitByWholeSeparatorPreserveAllTokens("", *)                 = []
7533     * StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null)      = ["ab", "de", "fg"]
7534     * StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null)    = ["ab", "", "", "de", "fg"]
7535     * StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
7536     * StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]
7537     * </pre>
7538     *
7539     * @param str  the String to parse, may be null
7540     * @param separator  String containing the String to be used as a delimiter,
7541     *  {@code null} splits on whitespace
7542     * @return an array of parsed Strings, {@code null} if null String was input
7543     * @since 2.4
7544     */
7545    public static String[] splitByWholeSeparatorPreserveAllTokens(final String str, final String separator) {
7546        return splitByWholeSeparatorWorker(str, separator, -1, true);
7547    }
7548
7549    /**
7550     * Splits the provided text into an array, separator string specified.
7551     * Returns a maximum of {@code max} substrings.
7552     *
7553     * <p>The separator is not included in the returned String array.
7554     * Adjacent separators are treated as separators for empty tokens.
7555     * For more control over the split use the StrTokenizer class.</p>
7556     *
7557     * <p>A {@code null} input String returns {@code null}.
7558     * A {@code null} separator splits on whitespace.</p>
7559     *
7560     * <pre>
7561     * StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *, *)               = null
7562     * StringUtils.splitByWholeSeparatorPreserveAllTokens("", *, *)                 = []
7563     * StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null, 0)      = ["ab", "de", "fg"]
7564     * StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null, 0)    = ["ab", "", "", "de", "fg"]
7565     * StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
7566     * StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
7567     * StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]
7568     * </pre>
7569     *
7570     * @param str  the String to parse, may be null
7571     * @param separator  String containing the String to be used as a delimiter,
7572     *  {@code null} splits on whitespace
7573     * @param max  the maximum number of elements to include in the returned
7574     *  array. A zero or negative value implies no limit.
7575     * @return an array of parsed Strings, {@code null} if null String was input
7576     * @since 2.4
7577     */
7578    public static String[] splitByWholeSeparatorPreserveAllTokens(final String str, final String separator, final int max) {
7579        return splitByWholeSeparatorWorker(str, separator, max, true);
7580    }
7581
7582    /**
7583     * Performs the logic for the {@code splitByWholeSeparatorPreserveAllTokens} methods.
7584     *
7585     * @param str  the String to parse, may be {@code null}
7586     * @param separator  String containing the String to be used as a delimiter,
7587     *  {@code null} splits on whitespace
7588     * @param max  the maximum number of elements to include in the returned
7589     *  array. A zero or negative value implies no limit.
7590     * @param preserveAllTokens if {@code true}, adjacent separators are
7591     * treated as empty token separators; if {@code false}, adjacent
7592     * separators are treated as one separator.
7593     * @return an array of parsed Strings, {@code null} if null String input
7594     * @since 2.4
7595     */
7596    private static String[] splitByWholeSeparatorWorker(
7597            final String str, final String separator, final int max, final boolean preserveAllTokens) {
7598        if (str == null) {
7599            return null;
7600        }
7601
7602        final int len = str.length();
7603
7604        if (len == 0) {
7605            return ArrayUtils.EMPTY_STRING_ARRAY;
7606        }
7607
7608        if (separator == null || EMPTY.equals(separator)) {
7609            // Split on whitespace.
7610            return splitWorker(str, null, max, preserveAllTokens);
7611        }
7612
7613        final int separatorLength = separator.length();
7614
7615        final ArrayList<String> substrings = new ArrayList<>();
7616        int numberOfSubstrings = 0;
7617        int beg = 0;
7618        int end = 0;
7619        while (end < len) {
7620            end = str.indexOf(separator, beg);
7621
7622            if (end > -1) {
7623                if (end > beg) {
7624                    numberOfSubstrings += 1;
7625
7626                    if (numberOfSubstrings == max) {
7627                        end = len;
7628                        substrings.add(str.substring(beg));
7629                    } else {
7630                        // The following is OK, because String.substring( beg, end ) excludes
7631                        // the character at the position 'end'.
7632                        substrings.add(str.substring(beg, end));
7633
7634                        // Set the starting point for the next search.
7635                        // The following is equivalent to beg = end + (separatorLength - 1) + 1,
7636                        // which is the right calculation:
7637                        beg = end + separatorLength;
7638                    }
7639                } else {
7640                    // We found a consecutive occurrence of the separator, so skip it.
7641                    if (preserveAllTokens) {
7642                        numberOfSubstrings += 1;
7643                        if (numberOfSubstrings == max) {
7644                            end = len;
7645                            substrings.add(str.substring(beg));
7646                        } else {
7647                            substrings.add(EMPTY);
7648                        }
7649                    }
7650                    beg = end + separatorLength;
7651                }
7652            } else {
7653                // String.substring( beg ) goes from 'beg' to the end of the String.
7654                substrings.add(str.substring(beg));
7655                end = len;
7656            }
7657        }
7658
7659        return substrings.toArray(ArrayUtils.EMPTY_STRING_ARRAY);
7660    }
7661
7662    /**
7663     * Splits the provided text into an array, using whitespace as the
7664     * separator, preserving all tokens, including empty tokens created by
7665     * adjacent separators. This is an alternative to using StringTokenizer.
7666     * Whitespace is defined by {@link Character#isWhitespace(char)}.
7667     *
7668     * <p>The separator is not included in the returned String array.
7669     * Adjacent separators are treated as separators for empty tokens.
7670     * For more control over the split use the StrTokenizer class.</p>
7671     *
7672     * <p>A {@code null} input String returns {@code null}.</p>
7673     *
7674     * <pre>
7675     * StringUtils.splitPreserveAllTokens(null)       = null
7676     * StringUtils.splitPreserveAllTokens("")         = []
7677     * StringUtils.splitPreserveAllTokens("abc def")  = ["abc", "def"]
7678     * StringUtils.splitPreserveAllTokens("abc  def") = ["abc", "", "def"]
7679     * StringUtils.splitPreserveAllTokens(" abc ")    = ["", "abc", ""]
7680     * </pre>
7681     *
7682     * @param str  the String to parse, may be {@code null}
7683     * @return an array of parsed Strings, {@code null} if null String input
7684     * @since 2.1
7685     */
7686    public static String[] splitPreserveAllTokens(final String str) {
7687        return splitWorker(str, null, -1, true);
7688    }
7689
7690    /**
7691     * Splits the provided text into an array, separator specified,
7692     * preserving all tokens, including empty tokens created by adjacent
7693     * separators. This is an alternative to using StringTokenizer.
7694     *
7695     * <p>The separator is not included in the returned String array.
7696     * Adjacent separators are treated as separators for empty tokens.
7697     * For more control over the split use the StrTokenizer class.</p>
7698     *
7699     * <p>A {@code null} input String returns {@code null}.</p>
7700     *
7701     * <pre>
7702     * StringUtils.splitPreserveAllTokens(null, *)         = null
7703     * StringUtils.splitPreserveAllTokens("", *)           = []
7704     * StringUtils.splitPreserveAllTokens("a.b.c", '.')    = ["a", "b", "c"]
7705     * StringUtils.splitPreserveAllTokens("a..b.c", '.')   = ["a", "", "b", "c"]
7706     * StringUtils.splitPreserveAllTokens("a:b:c", '.')    = ["a:b:c"]
7707     * StringUtils.splitPreserveAllTokens("a\tb\nc", null) = ["a", "b", "c"]
7708     * StringUtils.splitPreserveAllTokens("a b c", ' ')    = ["a", "b", "c"]
7709     * StringUtils.splitPreserveAllTokens("a b c ", ' ')   = ["a", "b", "c", ""]
7710     * StringUtils.splitPreserveAllTokens("a b c  ", ' ')   = ["a", "b", "c", "", ""]
7711     * StringUtils.splitPreserveAllTokens(" a b c", ' ')   = ["", a", "b", "c"]
7712     * StringUtils.splitPreserveAllTokens("  a b c", ' ')  = ["", "", a", "b", "c"]
7713     * StringUtils.splitPreserveAllTokens(" a b c ", ' ')  = ["", a", "b", "c", ""]
7714     * </pre>
7715     *
7716     * @param str  the String to parse, may be {@code null}
7717     * @param separatorChar  the character used as the delimiter,
7718     *  {@code null} splits on whitespace
7719     * @return an array of parsed Strings, {@code null} if null String input
7720     * @since 2.1
7721     */
7722    public static String[] splitPreserveAllTokens(final String str, final char separatorChar) {
7723        return splitWorker(str, separatorChar, true);
7724    }
7725
7726    /**
7727     * Splits the provided text into an array, separators specified,
7728     * preserving all tokens, including empty tokens created by adjacent
7729     * separators. This is an alternative to using StringTokenizer.
7730     *
7731     * <p>The separator is not included in the returned String array.
7732     * Adjacent separators are treated as separators for empty tokens.
7733     * For more control over the split use the StrTokenizer class.</p>
7734     *
7735     * <p>A {@code null} input String returns {@code null}.
7736     * A {@code null} separatorChars splits on whitespace.</p>
7737     *
7738     * <pre>
7739     * StringUtils.splitPreserveAllTokens(null, *)           = null
7740     * StringUtils.splitPreserveAllTokens("", *)             = []
7741     * StringUtils.splitPreserveAllTokens("abc def", null)   = ["abc", "def"]
7742     * StringUtils.splitPreserveAllTokens("abc def", " ")    = ["abc", "def"]
7743     * StringUtils.splitPreserveAllTokens("abc  def", " ")   = ["abc", "", def"]
7744     * StringUtils.splitPreserveAllTokens("ab:cd:ef", ":")   = ["ab", "cd", "ef"]
7745     * StringUtils.splitPreserveAllTokens("ab:cd:ef:", ":")  = ["ab", "cd", "ef", ""]
7746     * StringUtils.splitPreserveAllTokens("ab:cd:ef::", ":") = ["ab", "cd", "ef", "", ""]
7747     * StringUtils.splitPreserveAllTokens("ab::cd:ef", ":")  = ["ab", "", cd", "ef"]
7748     * StringUtils.splitPreserveAllTokens(":cd:ef", ":")     = ["", cd", "ef"]
7749     * StringUtils.splitPreserveAllTokens("::cd:ef", ":")    = ["", "", cd", "ef"]
7750     * StringUtils.splitPreserveAllTokens(":cd:ef:", ":")    = ["", cd", "ef", ""]
7751     * </pre>
7752     *
7753     * @param str  the String to parse, may be {@code null}
7754     * @param separatorChars  the characters used as the delimiters,
7755     *  {@code null} splits on whitespace
7756     * @return an array of parsed Strings, {@code null} if null String input
7757     * @since 2.1
7758     */
7759    public static String[] splitPreserveAllTokens(final String str, final String separatorChars) {
7760        return splitWorker(str, separatorChars, -1, true);
7761    }
7762
7763    /**
7764     * Splits the provided text into an array with a maximum length,
7765     * separators specified, preserving all tokens, including empty tokens
7766     * created by adjacent separators.
7767     *
7768     * <p>The separator is not included in the returned String array.
7769     * Adjacent separators are treated as separators for empty tokens.
7770     * Adjacent separators are treated as one separator.</p>
7771     *
7772     * <p>A {@code null} input String returns {@code null}.
7773     * A {@code null} separatorChars splits on whitespace.</p>
7774     *
7775     * <p>If more than {@code max} delimited substrings are found, the last
7776     * returned string includes all characters after the first {@code max - 1}
7777     * returned strings (including separator characters).</p>
7778     *
7779     * <pre>
7780     * StringUtils.splitPreserveAllTokens(null, *, *)            = null
7781     * StringUtils.splitPreserveAllTokens("", *, *)              = []
7782     * StringUtils.splitPreserveAllTokens("ab de fg", null, 0)   = ["ab", "de", "fg"]
7783     * StringUtils.splitPreserveAllTokens("ab   de fg", null, 0) = ["ab", "", "", "de", "fg"]
7784     * StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
7785     * StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]
7786     * StringUtils.splitPreserveAllTokens("ab   de fg", null, 2) = ["ab", "  de fg"]
7787     * StringUtils.splitPreserveAllTokens("ab   de fg", null, 3) = ["ab", "", " de fg"]
7788     * StringUtils.splitPreserveAllTokens("ab   de fg", null, 4) = ["ab", "", "", "de fg"]
7789     * </pre>
7790     *
7791     * @param str  the String to parse, may be {@code null}
7792     * @param separatorChars  the characters used as the delimiters,
7793     *  {@code null} splits on whitespace
7794     * @param max  the maximum number of elements to include in the
7795     *  array. A zero or negative value implies no limit
7796     * @return an array of parsed Strings, {@code null} if null String input
7797     * @since 2.1
7798     */
7799    public static String[] splitPreserveAllTokens(final String str, final String separatorChars, final int max) {
7800        return splitWorker(str, separatorChars, max, true);
7801    }
7802
7803    /**
7804     * Performs the logic for the {@code split} and
7805     * {@code splitPreserveAllTokens} methods that do not return a
7806     * maximum array length.
7807     *
7808     * @param str  the String to parse, may be {@code null}
7809     * @param separatorChar the separate character
7810     * @param preserveAllTokens if {@code true}, adjacent separators are
7811     * treated as empty token separators; if {@code false}, adjacent
7812     * separators are treated as one separator.
7813     * @return an array of parsed Strings, {@code null} if null String input
7814     */
7815    private static String[] splitWorker(final String str, final char separatorChar, final boolean preserveAllTokens) {
7816        // Performance tuned for 2.0 (JDK1.4)
7817
7818        if (str == null) {
7819            return null;
7820        }
7821        final int len = str.length();
7822        if (len == 0) {
7823            return ArrayUtils.EMPTY_STRING_ARRAY;
7824        }
7825        final List<String> list = new ArrayList<>();
7826        int i = 0;
7827        int start = 0;
7828        boolean match = false;
7829        boolean lastMatch = false;
7830        while (i < len) {
7831            if (str.charAt(i) == separatorChar) {
7832                if (match || preserveAllTokens) {
7833                    list.add(str.substring(start, i));
7834                    match = false;
7835                    lastMatch = true;
7836                }
7837                start = ++i;
7838                continue;
7839            }
7840            lastMatch = false;
7841            match = true;
7842            i++;
7843        }
7844        if (match || preserveAllTokens && lastMatch) {
7845            list.add(str.substring(start, i));
7846        }
7847        return list.toArray(ArrayUtils.EMPTY_STRING_ARRAY);
7848    }
7849
7850    /**
7851     * Performs the logic for the {@code split} and
7852     * {@code splitPreserveAllTokens} methods that return a maximum array
7853     * length.
7854     *
7855     * @param str  the String to parse, may be {@code null}
7856     * @param separatorChars the separate character
7857     * @param max  the maximum number of elements to include in the
7858     *  array. A zero or negative value implies no limit.
7859     * @param preserveAllTokens if {@code true}, adjacent separators are
7860     * treated as empty token separators; if {@code false}, adjacent
7861     * separators are treated as one separator.
7862     * @return an array of parsed Strings, {@code null} if null String input
7863     */
7864    private static String[] splitWorker(final String str, final String separatorChars, final int max, final boolean preserveAllTokens) {
7865        // Performance tuned for 2.0 (JDK1.4)
7866        // Direct code is quicker than StringTokenizer.
7867        // Also, StringTokenizer uses isSpace() not isWhitespace()
7868
7869        if (str == null) {
7870            return null;
7871        }
7872        final int len = str.length();
7873        if (len == 0) {
7874            return ArrayUtils.EMPTY_STRING_ARRAY;
7875        }
7876        final List<String> list = new ArrayList<>();
7877        int sizePlus1 = 1;
7878        int i = 0;
7879        int start = 0;
7880        boolean match = false;
7881        boolean lastMatch = false;
7882        if (separatorChars == null) {
7883            // Null separator means use whitespace
7884            while (i < len) {
7885                if (Character.isWhitespace(str.charAt(i))) {
7886                    if (match || preserveAllTokens) {
7887                        lastMatch = true;
7888                        if (sizePlus1++ == max) {
7889                            i = len;
7890                            lastMatch = false;
7891                        }
7892                        list.add(str.substring(start, i));
7893                        match = false;
7894                    }
7895                    start = ++i;
7896                    continue;
7897                }
7898                lastMatch = false;
7899                match = true;
7900                i++;
7901            }
7902        } else if (separatorChars.length() == 1) {
7903            // Optimise 1 character case
7904            final char sep = separatorChars.charAt(0);
7905            while (i < len) {
7906                if (str.charAt(i) == sep) {
7907                    if (match || preserveAllTokens) {
7908                        lastMatch = true;
7909                        if (sizePlus1++ == max) {
7910                            i = len;
7911                            lastMatch = false;
7912                        }
7913                        list.add(str.substring(start, i));
7914                        match = false;
7915                    }
7916                    start = ++i;
7917                    continue;
7918                }
7919                lastMatch = false;
7920                match = true;
7921                i++;
7922            }
7923        } else {
7924            // standard case
7925            while (i < len) {
7926                if (separatorChars.indexOf(str.charAt(i)) >= 0) {
7927                    if (match || preserveAllTokens) {
7928                        lastMatch = true;
7929                        if (sizePlus1++ == max) {
7930                            i = len;
7931                            lastMatch = false;
7932                        }
7933                        list.add(str.substring(start, i));
7934                        match = false;
7935                    }
7936                    start = ++i;
7937                    continue;
7938                }
7939                lastMatch = false;
7940                match = true;
7941                i++;
7942            }
7943        }
7944        if (match || preserveAllTokens && lastMatch) {
7945            list.add(str.substring(start, i));
7946        }
7947        return list.toArray(ArrayUtils.EMPTY_STRING_ARRAY);
7948    }
7949
7950    /**
7951     * Check if a CharSequence starts with a specified prefix.
7952     *
7953     * <p>{@code null}s are handled without exceptions. Two {@code null}
7954     * references are considered to be equal. The comparison is case-sensitive.</p>
7955     *
7956     * <pre>
7957     * StringUtils.startsWith(null, null)      = true
7958     * StringUtils.startsWith(null, "abc")     = false
7959     * StringUtils.startsWith("abcdef", null)  = false
7960     * StringUtils.startsWith("abcdef", "abc") = true
7961     * StringUtils.startsWith("ABCDEF", "abc") = false
7962     * </pre>
7963     *
7964     * @see String#startsWith(String)
7965     * @param str  the CharSequence to check, may be null
7966     * @param prefix the prefix to find, may be null
7967     * @return {@code true} if the CharSequence starts with the prefix, case-sensitive, or
7968     *  both {@code null}
7969     * @since 2.4
7970     * @since 3.0 Changed signature from startsWith(String, String) to startsWith(CharSequence, CharSequence)
7971     */
7972    public static boolean startsWith(final CharSequence str, final CharSequence prefix) {
7973        return startsWith(str, prefix, false);
7974    }
7975
7976    /**
7977     * Check if a CharSequence starts with a specified prefix (optionally case insensitive).
7978     *
7979     * @see String#startsWith(String)
7980     * @param str  the CharSequence to check, may be null
7981     * @param prefix the prefix to find, may be null
7982     * @param ignoreCase indicates whether the compare should ignore case
7983     *  (case-insensitive) or not.
7984     * @return {@code true} if the CharSequence starts with the prefix or
7985     *  both {@code null}
7986     */
7987    private static boolean startsWith(final CharSequence str, final CharSequence prefix, final boolean ignoreCase) {
7988        if (str == null || prefix == null) {
7989            return str == prefix;
7990        }
7991        // Get length once instead of twice in the unlikely case that it changes.
7992        final int preLen = prefix.length();
7993        if (preLen > str.length()) {
7994            return false;
7995        }
7996        return CharSequenceUtils.regionMatches(str, ignoreCase, 0, prefix, 0, preLen);
7997    }
7998
7999    /**
8000     * Check if a CharSequence starts with any of the provided case-sensitive prefixes.
8001     *
8002     * <pre>
8003     * StringUtils.startsWithAny(null, null)      = false
8004     * StringUtils.startsWithAny(null, new String[] {"abc"})  = false
8005     * StringUtils.startsWithAny("abcxyz", null)     = false
8006     * StringUtils.startsWithAny("abcxyz", new String[] {""}) = true
8007     * StringUtils.startsWithAny("abcxyz", new String[] {"abc"}) = true
8008     * StringUtils.startsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true
8009     * StringUtils.startsWithAny("abcxyz", null, "xyz", "ABCX") = false
8010     * StringUtils.startsWithAny("ABCXYZ", null, "xyz", "abc") = false
8011     * </pre>
8012     *
8013     * @param sequence the CharSequence to check, may be null
8014     * @param searchStrings the case-sensitive CharSequence prefixes, may be empty or contain {@code null}
8015     * @see StringUtils#startsWith(CharSequence, CharSequence)
8016     * @return {@code true} if the input {@code sequence} is {@code null} AND no {@code searchStrings} are provided, or
8017     *   the input {@code sequence} begins with any of the provided case-sensitive {@code searchStrings}.
8018     * @since 2.5
8019     * @since 3.0 Changed signature from startsWithAny(String, String[]) to startsWithAny(CharSequence, CharSequence...)
8020     */
8021    public static boolean startsWithAny(final CharSequence sequence, final CharSequence... searchStrings) {
8022        if (isEmpty(sequence) || ArrayUtils.isEmpty(searchStrings)) {
8023            return false;
8024        }
8025        for (final CharSequence searchString : searchStrings) {
8026            if (startsWith(sequence, searchString)) {
8027                return true;
8028            }
8029        }
8030        return false;
8031    }
8032
8033    /**
8034     * Case insensitive check if a CharSequence starts with a specified prefix.
8035     *
8036     * <p>{@code null}s are handled without exceptions. Two {@code null}
8037     * references are considered to be equal. The comparison is case insensitive.</p>
8038     *
8039     * <pre>
8040     * StringUtils.startsWithIgnoreCase(null, null)      = true
8041     * StringUtils.startsWithIgnoreCase(null, "abc")     = false
8042     * StringUtils.startsWithIgnoreCase("abcdef", null)  = false
8043     * StringUtils.startsWithIgnoreCase("abcdef", "abc") = true
8044     * StringUtils.startsWithIgnoreCase("ABCDEF", "abc") = true
8045     * </pre>
8046     *
8047     * @see String#startsWith(String)
8048     * @param str  the CharSequence to check, may be null
8049     * @param prefix the prefix to find, may be null
8050     * @return {@code true} if the CharSequence starts with the prefix, case-insensitive, or
8051     *  both {@code null}
8052     * @since 2.4
8053     * @since 3.0 Changed signature from startsWithIgnoreCase(String, String) to startsWithIgnoreCase(CharSequence, CharSequence)
8054     */
8055    public static boolean startsWithIgnoreCase(final CharSequence str, final CharSequence prefix) {
8056        return startsWith(str, prefix, true);
8057    }
8058
8059    /**
8060     * Strips whitespace from the start and end of a String.
8061     *
8062     * <p>This is similar to {@link #trim(String)} but removes whitespace.
8063     * Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
8064     *
8065     * <p>A {@code null} input String returns {@code null}.</p>
8066     *
8067     * <pre>
8068     * StringUtils.strip(null)     = null
8069     * StringUtils.strip("")       = ""
8070     * StringUtils.strip("   ")    = ""
8071     * StringUtils.strip("abc")    = "abc"
8072     * StringUtils.strip("  abc")  = "abc"
8073     * StringUtils.strip("abc  ")  = "abc"
8074     * StringUtils.strip(" abc ")  = "abc"
8075     * StringUtils.strip(" ab c ") = "ab c"
8076     * </pre>
8077     *
8078     * @param str  the String to remove whitespace from, may be null
8079     * @return the stripped String, {@code null} if null String input
8080     */
8081    public static String strip(final String str) {
8082        return strip(str, null);
8083    }
8084
8085    /**
8086     * Strips any of a set of characters from the start and end of a String.
8087     * This is similar to {@link String#trim()} but allows the characters
8088     * to be stripped to be controlled.
8089     *
8090     * <p>A {@code null} input String returns {@code null}.
8091     * An empty string ("") input returns the empty string.</p>
8092     *
8093     * <p>If the stripChars String is {@code null}, whitespace is
8094     * stripped as defined by {@link Character#isWhitespace(char)}.
8095     * Alternatively use {@link #strip(String)}.</p>
8096     *
8097     * <pre>
8098     * StringUtils.strip(null, *)          = null
8099     * StringUtils.strip("", *)            = ""
8100     * StringUtils.strip("abc", null)      = "abc"
8101     * StringUtils.strip("  abc", null)    = "abc"
8102     * StringUtils.strip("abc  ", null)    = "abc"
8103     * StringUtils.strip(" abc ", null)    = "abc"
8104     * StringUtils.strip("  abcyx", "xyz") = "  abc"
8105     * </pre>
8106     *
8107     * @param str  the String to remove characters from, may be null
8108     * @param stripChars  the characters to remove, null treated as whitespace
8109     * @return the stripped String, {@code null} if null String input
8110     */
8111    public static String strip(String str, final String stripChars) {
8112        str = stripStart(str, stripChars);
8113        return stripEnd(str, stripChars);
8114    }
8115
8116    /**
8117     * Removes diacritics (~= accents) from a string. The case will not be altered.
8118     * <p>For instance, '&agrave;' will be replaced by 'a'.</p>
8119     * <p>Note that ligatures will be left as is.</p>
8120     *
8121     * <pre>
8122     * StringUtils.stripAccents(null)                = null
8123     * StringUtils.stripAccents("")                  = ""
8124     * StringUtils.stripAccents("control")           = "control"
8125     * StringUtils.stripAccents("&eacute;clair")     = "eclair"
8126     * </pre>
8127     *
8128     * @param input String to be stripped
8129     * @return input text with diacritics removed
8130     *
8131     * @since 3.0
8132     */
8133    // See also Lucene's ASCIIFoldingFilter (Lucene 2.9) that replaces accented characters by their unaccented equivalent (and uncommitted bug fix: https://issues.apache.org/jira/browse/LUCENE-1343?focusedCommentId=12858907&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#action_12858907).
8134    public static String stripAccents(final String input) {
8135        if (input == null) {
8136            return null;
8137        }
8138        final StringBuilder decomposed = new StringBuilder(Normalizer.normalize(input, Normalizer.Form.NFD));
8139        convertRemainingAccentCharacters(decomposed);
8140        // Note that this doesn't correctly remove ligatures...
8141        return STRIP_ACCENTS_PATTERN.matcher(decomposed).replaceAll(EMPTY);
8142    }
8143
8144    /**
8145     * Strips whitespace from the start and end of every String in an array.
8146     * Whitespace is defined by {@link Character#isWhitespace(char)}.
8147     *
8148     * <p>A new array is returned each time, except for length zero.
8149     * A {@code null} array will return {@code null}.
8150     * An empty array will return itself.
8151     * A {@code null} array entry will be ignored.</p>
8152     *
8153     * <pre>
8154     * StringUtils.stripAll(null)             = null
8155     * StringUtils.stripAll([])               = []
8156     * StringUtils.stripAll(["abc", "  abc"]) = ["abc", "abc"]
8157     * StringUtils.stripAll(["abc  ", null])  = ["abc", null]
8158     * </pre>
8159     *
8160     * @param strs  the array to remove whitespace from, may be null
8161     * @return the stripped Strings, {@code null} if null array input
8162     */
8163    public static String[] stripAll(final String... strs) {
8164        return stripAll(strs, null);
8165    }
8166
8167    /**
8168     * Strips any of a set of characters from the start and end of every
8169     * String in an array.
8170     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
8171     *
8172     * <p>A new array is returned each time, except for length zero.
8173     * A {@code null} array will return {@code null}.
8174     * An empty array will return itself.
8175     * A {@code null} array entry will be ignored.
8176     * A {@code null} stripChars will strip whitespace as defined by
8177     * {@link Character#isWhitespace(char)}.</p>
8178     *
8179     * <pre>
8180     * StringUtils.stripAll(null, *)                = null
8181     * StringUtils.stripAll([], *)                  = []
8182     * StringUtils.stripAll(["abc", "  abc"], null) = ["abc", "abc"]
8183     * StringUtils.stripAll(["abc  ", null], null)  = ["abc", null]
8184     * StringUtils.stripAll(["abc  ", null], "yz")  = ["abc  ", null]
8185     * StringUtils.stripAll(["yabcz", null], "yz")  = ["abc", null]
8186     * </pre>
8187     *
8188     * @param strs  the array to remove characters from, may be null
8189     * @param stripChars  the characters to remove, null treated as whitespace
8190     * @return the stripped Strings, {@code null} if null array input
8191     */
8192    public static String[] stripAll(final String[] strs, final String stripChars) {
8193        final int strsLen = ArrayUtils.getLength(strs);
8194        if (strsLen == 0) {
8195            return strs;
8196        }
8197        final String[] newArr = new String[strsLen];
8198        Arrays.setAll(newArr, i -> strip(strs[i], stripChars));
8199        return newArr;
8200    }
8201
8202    /**
8203     * Strips any of a set of characters from the end of a String.
8204     *
8205     * <p>A {@code null} input String returns {@code null}.
8206     * An empty string ("") input returns the empty string.</p>
8207     *
8208     * <p>If the stripChars String is {@code null}, whitespace is
8209     * stripped as defined by {@link Character#isWhitespace(char)}.</p>
8210     *
8211     * <pre>
8212     * StringUtils.stripEnd(null, *)          = null
8213     * StringUtils.stripEnd("", *)            = ""
8214     * StringUtils.stripEnd("abc", "")        = "abc"
8215     * StringUtils.stripEnd("abc", null)      = "abc"
8216     * StringUtils.stripEnd("  abc", null)    = "  abc"
8217     * StringUtils.stripEnd("abc  ", null)    = "abc"
8218     * StringUtils.stripEnd(" abc ", null)    = " abc"
8219     * StringUtils.stripEnd("  abcyx", "xyz") = "  abc"
8220     * StringUtils.stripEnd("120.00", ".0")   = "12"
8221     * </pre>
8222     *
8223     * @param str  the String to remove characters from, may be null
8224     * @param stripChars  the set of characters to remove, null treated as whitespace
8225     * @return the stripped String, {@code null} if null String input
8226     */
8227    public static String stripEnd(final String str, final String stripChars) {
8228        int end = length(str);
8229        if (end == 0) {
8230            return str;
8231        }
8232
8233        if (stripChars == null) {
8234            while (end != 0 && Character.isWhitespace(str.charAt(end - 1))) {
8235                end--;
8236            }
8237        } else if (stripChars.isEmpty()) {
8238            return str;
8239        } else {
8240            while (end != 0 && stripChars.indexOf(str.charAt(end - 1)) != INDEX_NOT_FOUND) {
8241                end--;
8242            }
8243        }
8244        return str.substring(0, end);
8245    }
8246
8247    /**
8248     * Strips any of a set of characters from the start of a String.
8249     *
8250     * <p>A {@code null} input String returns {@code null}.
8251     * An empty string ("") input returns the empty string.</p>
8252     *
8253     * <p>If the stripChars String is {@code null}, whitespace is
8254     * stripped as defined by {@link Character#isWhitespace(char)}.</p>
8255     *
8256     * <pre>
8257     * StringUtils.stripStart(null, *)          = null
8258     * StringUtils.stripStart("", *)            = ""
8259     * StringUtils.stripStart("abc", "")        = "abc"
8260     * StringUtils.stripStart("abc", null)      = "abc"
8261     * StringUtils.stripStart("  abc", null)    = "abc"
8262     * StringUtils.stripStart("abc  ", null)    = "abc  "
8263     * StringUtils.stripStart(" abc ", null)    = "abc "
8264     * StringUtils.stripStart("yxabc  ", "xyz") = "abc  "
8265     * </pre>
8266     *
8267     * @param str  the String to remove characters from, may be null
8268     * @param stripChars  the characters to remove, null treated as whitespace
8269     * @return the stripped String, {@code null} if null String input
8270     */
8271    public static String stripStart(final String str, final String stripChars) {
8272        final int strLen = length(str);
8273        if (strLen == 0) {
8274            return str;
8275        }
8276        int start = 0;
8277        if (stripChars == null) {
8278            while (start != strLen && Character.isWhitespace(str.charAt(start))) {
8279                start++;
8280            }
8281        } else if (stripChars.isEmpty()) {
8282            return str;
8283        } else {
8284            while (start != strLen && stripChars.indexOf(str.charAt(start)) != INDEX_NOT_FOUND) {
8285                start++;
8286            }
8287        }
8288        return str.substring(start);
8289    }
8290
8291    /**
8292     * Strips whitespace from the start and end of a String  returning
8293     * an empty String if {@code null} input.
8294     *
8295     * <p>This is similar to {@link #trimToEmpty(String)} but removes whitespace.
8296     * Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
8297     *
8298     * <pre>
8299     * StringUtils.stripToEmpty(null)     = ""
8300     * StringUtils.stripToEmpty("")       = ""
8301     * StringUtils.stripToEmpty("   ")    = ""
8302     * StringUtils.stripToEmpty("abc")    = "abc"
8303     * StringUtils.stripToEmpty("  abc")  = "abc"
8304     * StringUtils.stripToEmpty("abc  ")  = "abc"
8305     * StringUtils.stripToEmpty(" abc ")  = "abc"
8306     * StringUtils.stripToEmpty(" ab c ") = "ab c"
8307     * </pre>
8308     *
8309     * @param str  the String to be stripped, may be null
8310     * @return the trimmed String, or an empty String if {@code null} input
8311     * @since 2.0
8312     */
8313    public static String stripToEmpty(final String str) {
8314        return str == null ? EMPTY : strip(str, null);
8315    }
8316
8317    /**
8318     * Strips whitespace from the start and end of a String  returning
8319     * {@code null} if the String is empty ("") after the strip.
8320     *
8321     * <p>This is similar to {@link #trimToNull(String)} but removes whitespace.
8322     * Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
8323     *
8324     * <pre>
8325     * StringUtils.stripToNull(null)     = null
8326     * StringUtils.stripToNull("")       = null
8327     * StringUtils.stripToNull("   ")    = null
8328     * StringUtils.stripToNull("abc")    = "abc"
8329     * StringUtils.stripToNull("  abc")  = "abc"
8330     * StringUtils.stripToNull("abc  ")  = "abc"
8331     * StringUtils.stripToNull(" abc ")  = "abc"
8332     * StringUtils.stripToNull(" ab c ") = "ab c"
8333     * </pre>
8334     *
8335     * @param str  the String to be stripped, may be null
8336     * @return the stripped String,
8337     *  {@code null} if whitespace, empty or null String input
8338     * @since 2.0
8339     */
8340    public static String stripToNull(String str) {
8341        if (str == null) {
8342            return null;
8343        }
8344        str = strip(str, null);
8345        return str.isEmpty() ? null : str; // NOSONARLINT str cannot be null here
8346    }
8347
8348    /**
8349     * Gets a substring from the specified String avoiding exceptions.
8350     *
8351     * <p>A negative start position can be used to start {@code n}
8352     * characters from the end of the String.</p>
8353     *
8354     * <p>A {@code null} String will return {@code null}.
8355     * An empty ("") String will return "".</p>
8356     *
8357     * <pre>
8358     * StringUtils.substring(null, *)   = null
8359     * StringUtils.substring("", *)     = ""
8360     * StringUtils.substring("abc", 0)  = "abc"
8361     * StringUtils.substring("abc", 2)  = "c"
8362     * StringUtils.substring("abc", 4)  = ""
8363     * StringUtils.substring("abc", -2) = "bc"
8364     * StringUtils.substring("abc", -4) = "abc"
8365     * </pre>
8366     *
8367     * @param str  the String to get the substring from, may be null
8368     * @param start  the position to start from, negative means
8369     *  count back from the end of the String by this many characters
8370     * @return substring from start position, {@code null} if null String input
8371     */
8372    public static String substring(final String str, int start) {
8373        if (str == null) {
8374            return null;
8375        }
8376
8377        // handle negatives, which means last n characters
8378        if (start < 0) {
8379            start = str.length() + start; // remember start is negative
8380        }
8381
8382        if (start < 0) {
8383            start = 0;
8384        }
8385        if (start > str.length()) {
8386            return EMPTY;
8387        }
8388
8389        return str.substring(start);
8390    }
8391
8392    /**
8393     * Gets a substring from the specified String avoiding exceptions.
8394     *
8395     * <p>A negative start position can be used to start/end {@code n}
8396     * characters from the end of the String.</p>
8397     *
8398     * <p>The returned substring starts with the character in the {@code start}
8399     * position and ends before the {@code end} position. All position counting is
8400     * zero-based -- i.e., to start at the beginning of the string use
8401     * {@code start = 0}. Negative start and end positions can be used to
8402     * specify offsets relative to the end of the String.</p>
8403     *
8404     * <p>If {@code start} is not strictly to the left of {@code end}, ""
8405     * is returned.</p>
8406     *
8407     * <pre>
8408     * StringUtils.substring(null, *, *)    = null
8409     * StringUtils.substring("", * ,  *)    = "";
8410     * StringUtils.substring("abc", 0, 2)   = "ab"
8411     * StringUtils.substring("abc", 2, 0)   = ""
8412     * StringUtils.substring("abc", 2, 4)   = "c"
8413     * StringUtils.substring("abc", 4, 6)   = ""
8414     * StringUtils.substring("abc", 2, 2)   = ""
8415     * StringUtils.substring("abc", -2, -1) = "b"
8416     * StringUtils.substring("abc", -4, 2)  = "ab"
8417     * </pre>
8418     *
8419     * @param str  the String to get the substring from, may be null
8420     * @param start  the position to start from, negative means
8421     *  count back from the end of the String by this many characters
8422     * @param end  the position to end at (exclusive), negative means
8423     *  count back from the end of the String by this many characters
8424     * @return substring from start position to end position,
8425     *  {@code null} if null String input
8426     */
8427    public static String substring(final String str, int start, int end) {
8428        if (str == null) {
8429            return null;
8430        }
8431
8432        // handle negatives
8433        if (end < 0) {
8434            end = str.length() + end; // remember end is negative
8435        }
8436        if (start < 0) {
8437            start = str.length() + start; // remember start is negative
8438        }
8439
8440        // check length next
8441        if (end > str.length()) {
8442            end = str.length();
8443        }
8444
8445        // if start is greater than end, return ""
8446        if (start > end) {
8447            return EMPTY;
8448        }
8449
8450        if (start < 0) {
8451            start = 0;
8452        }
8453        if (end < 0) {
8454            end = 0;
8455        }
8456
8457        return str.substring(start, end);
8458    }
8459
8460    /**
8461     * Gets the substring after the first occurrence of a separator.
8462     * The separator is not returned.
8463     *
8464     * <p>A {@code null} string input will return {@code null}.
8465     * An empty ("") string input will return the empty string.
8466     *
8467     * <p>If nothing is found, the empty string is returned.</p>
8468     *
8469     * <pre>
8470     * StringUtils.substringAfter(null, *)      = null
8471     * StringUtils.substringAfter("", *)        = ""
8472     * StringUtils.substringAfter("abc", 'a')   = "bc"
8473     * StringUtils.substringAfter("abcba", 'b') = "cba"
8474     * StringUtils.substringAfter("abc", 'c')   = ""
8475     * StringUtils.substringAfter("abc", 'd')   = ""
8476     * StringUtils.substringAfter(" abc", 32)   = "abc"
8477     * </pre>
8478     *
8479     * @param str  the String to get a substring from, may be null
8480     * @param separator  the character (Unicode code point) to search.
8481     * @return the substring after the first occurrence of the separator,
8482     *  {@code null} if null String input
8483     * @since 3.11
8484     */
8485    public static String substringAfter(final String str, final int separator) {
8486        if (isEmpty(str)) {
8487            return str;
8488        }
8489        final int pos = str.indexOf(separator);
8490        if (pos == INDEX_NOT_FOUND) {
8491            return EMPTY;
8492        }
8493        return str.substring(pos + 1);
8494    }
8495
8496    /**
8497     * Gets the substring after the first occurrence of a separator.
8498     * The separator is not returned.
8499     *
8500     * <p>A {@code null} string input will return {@code null}.
8501     * An empty ("") string input will return the empty string.
8502     * A {@code null} separator will return the empty string if the
8503     * input string is not {@code null}.</p>
8504     *
8505     * <p>If nothing is found, the empty string is returned.</p>
8506     *
8507     * <pre>
8508     * StringUtils.substringAfter(null, *)      = null
8509     * StringUtils.substringAfter("", *)        = ""
8510     * StringUtils.substringAfter(*, null)      = ""
8511     * StringUtils.substringAfter("abc", "a")   = "bc"
8512     * StringUtils.substringAfter("abcba", "b") = "cba"
8513     * StringUtils.substringAfter("abc", "c")   = ""
8514     * StringUtils.substringAfter("abc", "d")   = ""
8515     * StringUtils.substringAfter("abc", "")    = "abc"
8516     * </pre>
8517     *
8518     * @param str  the String to get a substring from, may be null
8519     * @param separator  the String to search for, may be null
8520     * @return the substring after the first occurrence of the separator,
8521     *  {@code null} if null String input
8522     * @since 2.0
8523     */
8524    public static String substringAfter(final String str, final String separator) {
8525        if (isEmpty(str)) {
8526            return str;
8527        }
8528        if (separator == null) {
8529            return EMPTY;
8530        }
8531        final int pos = str.indexOf(separator);
8532        if (pos == INDEX_NOT_FOUND) {
8533            return EMPTY;
8534        }
8535        return str.substring(pos + separator.length());
8536    }
8537
8538    /**
8539     * Gets the substring after the last occurrence of a separator.
8540     * The separator is not returned.
8541     *
8542     * <p>A {@code null} string input will return {@code null}.
8543     * An empty ("") string input will return the empty string.
8544     *
8545     * <p>If nothing is found, the empty string is returned.</p>
8546     *
8547     * <pre>
8548     * StringUtils.substringAfterLast(null, *)      = null
8549     * StringUtils.substringAfterLast("", *)        = ""
8550     * StringUtils.substringAfterLast("abc", 'a')   = "bc"
8551     * StringUtils.substringAfterLast(" bc", 32)    = "bc"
8552     * StringUtils.substringAfterLast("abcba", 'b') = "a"
8553     * StringUtils.substringAfterLast("abc", 'c')   = ""
8554     * StringUtils.substringAfterLast("a", 'a')     = ""
8555     * StringUtils.substringAfterLast("a", 'z')     = ""
8556     * </pre>
8557     *
8558     * @param str  the String to get a substring from, may be null
8559     * @param separator  the character (Unicode code point) to search.
8560     * @return the substring after the last occurrence of the separator,
8561     *  {@code null} if null String input
8562     * @since 3.11
8563     */
8564    public static String substringAfterLast(final String str, final int separator) {
8565        if (isEmpty(str)) {
8566            return str;
8567        }
8568        final int pos = str.lastIndexOf(separator);
8569        if (pos == INDEX_NOT_FOUND || pos == str.length() - 1) {
8570            return EMPTY;
8571        }
8572        return str.substring(pos + 1);
8573    }
8574
8575    /**
8576     * Gets the substring after the last occurrence of a separator.
8577     * The separator is not returned.
8578     *
8579     * <p>A {@code null} string input will return {@code null}.
8580     * An empty ("") string input will return the empty string.
8581     * An empty or {@code null} separator will return the empty string if
8582     * the input string is not {@code null}.</p>
8583     *
8584     * <p>If nothing is found, the empty string is returned.</p>
8585     *
8586     * <pre>
8587     * StringUtils.substringAfterLast(null, *)      = null
8588     * StringUtils.substringAfterLast("", *)        = ""
8589     * StringUtils.substringAfterLast(*, "")        = ""
8590     * StringUtils.substringAfterLast(*, null)      = ""
8591     * StringUtils.substringAfterLast("abc", "a")   = "bc"
8592     * StringUtils.substringAfterLast("abcba", "b") = "a"
8593     * StringUtils.substringAfterLast("abc", "c")   = ""
8594     * StringUtils.substringAfterLast("a", "a")     = ""
8595     * StringUtils.substringAfterLast("a", "z")     = ""
8596     * </pre>
8597     *
8598     * @param str  the String to get a substring from, may be null
8599     * @param separator  the String to search for, may be null
8600     * @return the substring after the last occurrence of the separator,
8601     *  {@code null} if null String input
8602     * @since 2.0
8603     */
8604    public static String substringAfterLast(final String str, final String separator) {
8605        if (isEmpty(str)) {
8606            return str;
8607        }
8608        if (isEmpty(separator)) {
8609            return EMPTY;
8610        }
8611        final int pos = str.lastIndexOf(separator);
8612        if (pos == INDEX_NOT_FOUND || pos == str.length() - separator.length()) {
8613            return EMPTY;
8614        }
8615        return str.substring(pos + separator.length());
8616    }
8617
8618    /**
8619     * Gets the substring before the first occurrence of a separator. The separator is not returned.
8620     *
8621     * <p>
8622     * A {@code null} string input will return {@code null}. An empty ("") string input will return the empty string.
8623     * </p>
8624     *
8625     * <p>
8626     * If nothing is found, the string input is returned.
8627     * </p>
8628     *
8629     * <pre>
8630     * StringUtils.substringBefore(null, *)      = null
8631     * StringUtils.substringBefore("", *)        = ""
8632     * StringUtils.substringBefore("abc", 'a')   = ""
8633     * StringUtils.substringBefore("abcba", 'b') = "a"
8634     * StringUtils.substringBefore("abc", 'c')   = "ab"
8635     * StringUtils.substringBefore("abc", 'd')   = "abc"
8636     * </pre>
8637     *
8638     * @param str the String to get a substring from, may be null
8639     * @param separator the character (Unicode code point) to search.
8640     * @return the substring before the first occurrence of the separator, {@code null} if null String input
8641     * @since 3.12.0
8642     */
8643    public static String substringBefore(final String str, final int separator) {
8644        if (isEmpty(str)) {
8645            return str;
8646        }
8647        final int pos = str.indexOf(separator);
8648        if (pos == INDEX_NOT_FOUND) {
8649            return str;
8650        }
8651        return str.substring(0, pos);
8652    }
8653
8654    /**
8655     * Gets the substring before the first occurrence of a separator.
8656     * The separator is not returned.
8657     *
8658     * <p>A {@code null} string input will return {@code null}.
8659     * An empty ("") string input will return the empty string.
8660     * A {@code null} separator will return the input string.</p>
8661     *
8662     * <p>If nothing is found, the string input is returned.</p>
8663     *
8664     * <pre>
8665     * StringUtils.substringBefore(null, *)      = null
8666     * StringUtils.substringBefore("", *)        = ""
8667     * StringUtils.substringBefore("abc", "a")   = ""
8668     * StringUtils.substringBefore("abcba", "b") = "a"
8669     * StringUtils.substringBefore("abc", "c")   = "ab"
8670     * StringUtils.substringBefore("abc", "d")   = "abc"
8671     * StringUtils.substringBefore("abc", "")    = ""
8672     * StringUtils.substringBefore("abc", null)  = "abc"
8673     * </pre>
8674     *
8675     * @param str  the String to get a substring from, may be null
8676     * @param separator  the String to search for, may be null
8677     * @return the substring before the first occurrence of the separator,
8678     *  {@code null} if null String input
8679     * @since 2.0
8680     */
8681    public static String substringBefore(final String str, final String separator) {
8682        if (isEmpty(str) || separator == null) {
8683            return str;
8684        }
8685        if (separator.isEmpty()) {
8686            return EMPTY;
8687        }
8688        final int pos = str.indexOf(separator);
8689        if (pos == INDEX_NOT_FOUND) {
8690            return str;
8691        }
8692        return str.substring(0, pos);
8693    }
8694
8695    /**
8696     * Gets the substring before the last occurrence of a separator.
8697     * The separator is not returned.
8698     *
8699     * <p>A {@code null} string input will return {@code null}.
8700     * An empty ("") string input will return the empty string.
8701     * An empty or {@code null} separator will return the input string.</p>
8702     *
8703     * <p>If nothing is found, the string input is returned.</p>
8704     *
8705     * <pre>
8706     * StringUtils.substringBeforeLast(null, *)      = null
8707     * StringUtils.substringBeforeLast("", *)        = ""
8708     * StringUtils.substringBeforeLast("abcba", "b") = "abc"
8709     * StringUtils.substringBeforeLast("abc", "c")   = "ab"
8710     * StringUtils.substringBeforeLast("a", "a")     = ""
8711     * StringUtils.substringBeforeLast("a", "z")     = "a"
8712     * StringUtils.substringBeforeLast("a", null)    = "a"
8713     * StringUtils.substringBeforeLast("a", "")      = "a"
8714     * </pre>
8715     *
8716     * @param str  the String to get a substring from, may be null
8717     * @param separator  the String to search for, may be null
8718     * @return the substring before the last occurrence of the separator,
8719     *  {@code null} if null String input
8720     * @since 2.0
8721     */
8722    public static String substringBeforeLast(final String str, final String separator) {
8723        if (isEmpty(str) || isEmpty(separator)) {
8724            return str;
8725        }
8726        final int pos = str.lastIndexOf(separator);
8727        if (pos == INDEX_NOT_FOUND) {
8728            return str;
8729        }
8730        return str.substring(0, pos);
8731    }
8732
8733    /**
8734     * Gets the String that is nested in between two instances of the
8735     * same String.
8736     *
8737     * <p>A {@code null} input String returns {@code null}.
8738     * A {@code null} tag returns {@code null}.</p>
8739     *
8740     * <pre>
8741     * StringUtils.substringBetween(null, *)            = null
8742     * StringUtils.substringBetween("", "")             = ""
8743     * StringUtils.substringBetween("", "tag")          = null
8744     * StringUtils.substringBetween("tagabctag", null)  = null
8745     * StringUtils.substringBetween("tagabctag", "")    = ""
8746     * StringUtils.substringBetween("tagabctag", "tag") = "abc"
8747     * </pre>
8748     *
8749     * @param str  the String containing the substring, may be null
8750     * @param tag  the String before and after the substring, may be null
8751     * @return the substring, {@code null} if no match
8752     * @since 2.0
8753     */
8754    public static String substringBetween(final String str, final String tag) {
8755        return substringBetween(str, tag, tag);
8756    }
8757
8758    /**
8759     * Gets the String that is nested in between two Strings.
8760     * Only the first match is returned.
8761     *
8762     * <p>A {@code null} input String returns {@code null}.
8763     * A {@code null} open/close returns {@code null} (no match).
8764     * An empty ("") open and close returns an empty string.</p>
8765     *
8766     * <pre>
8767     * StringUtils.substringBetween("wx[b]yz", "[", "]") = "b"
8768     * StringUtils.substringBetween(null, *, *)          = null
8769     * StringUtils.substringBetween(*, null, *)          = null
8770     * StringUtils.substringBetween(*, *, null)          = null
8771     * StringUtils.substringBetween("", "", "")          = ""
8772     * StringUtils.substringBetween("", "", "]")         = null
8773     * StringUtils.substringBetween("", "[", "]")        = null
8774     * StringUtils.substringBetween("yabcz", "", "")     = ""
8775     * StringUtils.substringBetween("yabcz", "y", "z")   = "abc"
8776     * StringUtils.substringBetween("yabczyabcz", "y", "z")   = "abc"
8777     * </pre>
8778     *
8779     * @param str  the String containing the substring, may be null
8780     * @param open  the String before the substring, may be null
8781     * @param close  the String after the substring, may be null
8782     * @return the substring, {@code null} if no match
8783     * @since 2.0
8784     */
8785    public static String substringBetween(final String str, final String open, final String close) {
8786        if (!ObjectUtils.allNotNull(str, open, close)) {
8787            return null;
8788        }
8789        final int start = str.indexOf(open);
8790        if (start != INDEX_NOT_FOUND) {
8791            final int end = str.indexOf(close, start + open.length());
8792            if (end != INDEX_NOT_FOUND) {
8793                return str.substring(start + open.length(), end);
8794            }
8795        }
8796        return null;
8797    }
8798
8799    /**
8800     * Searches a String for substrings delimited by a start and end tag,
8801     * returning all matching substrings in an array.
8802     *
8803     * <p>A {@code null} input String returns {@code null}.
8804     * A {@code null} open/close returns {@code null} (no match).
8805     * An empty ("") open/close returns {@code null} (no match).</p>
8806     *
8807     * <pre>
8808     * StringUtils.substringsBetween("[a][b][c]", "[", "]") = ["a","b","c"]
8809     * StringUtils.substringsBetween(null, *, *)            = null
8810     * StringUtils.substringsBetween(*, null, *)            = null
8811     * StringUtils.substringsBetween(*, *, null)            = null
8812     * StringUtils.substringsBetween("", "[", "]")          = []
8813     * </pre>
8814     *
8815     * @param str  the String containing the substrings, null returns null, empty returns empty
8816     * @param open  the String identifying the start of the substring, empty returns null
8817     * @param close  the String identifying the end of the substring, empty returns null
8818     * @return a String Array of substrings, or {@code null} if no match
8819     * @since 2.3
8820     */
8821    public static String[] substringsBetween(final String str, final String open, final String close) {
8822        if (str == null || isEmpty(open) || isEmpty(close)) {
8823            return null;
8824        }
8825        final int strLen = str.length();
8826        if (strLen == 0) {
8827            return ArrayUtils.EMPTY_STRING_ARRAY;
8828        }
8829        final int closeLen = close.length();
8830        final int openLen = open.length();
8831        final List<String> list = new ArrayList<>();
8832        int pos = 0;
8833        while (pos < strLen - closeLen) {
8834            int start = str.indexOf(open, pos);
8835            if (start < 0) {
8836                break;
8837            }
8838            start += openLen;
8839            final int end = str.indexOf(close, start);
8840            if (end < 0) {
8841                break;
8842            }
8843            list.add(str.substring(start, end));
8844            pos = end + closeLen;
8845        }
8846        if (list.isEmpty()) {
8847            return null;
8848        }
8849        return list.toArray(ArrayUtils.EMPTY_STRING_ARRAY);
8850    }
8851
8852    /**
8853     * Swaps the case of a String changing upper and title case to
8854     * lower case, and lower case to upper case.
8855     *
8856     * <ul>
8857     *  <li>Upper case character converts to Lower case</li>
8858     *  <li>Title case character converts to Lower case</li>
8859     *  <li>Lower case character converts to Upper case</li>
8860     * </ul>
8861     *
8862     * <p>For a word based algorithm, see {@link org.apache.commons.text.WordUtils#swapCase(String)}.
8863     * A {@code null} input String returns {@code null}.</p>
8864     *
8865     * <pre>
8866     * StringUtils.swapCase(null)                 = null
8867     * StringUtils.swapCase("")                   = ""
8868     * StringUtils.swapCase("The dog has a BONE") = "tHE DOG HAS A bone"
8869     * </pre>
8870     *
8871     * <p>NOTE: This method changed in Lang version 2.0.
8872     * It no longer performs a word based algorithm.
8873     * If you only use ASCII, you will notice no change.
8874     * That functionality is available in org.apache.commons.lang3.text.WordUtils.</p>
8875     *
8876     * @param str  the String to swap case, may be null
8877     * @return the changed String, {@code null} if null String input
8878     */
8879    public static String swapCase(final String str) {
8880        if (isEmpty(str)) {
8881            return str;
8882        }
8883
8884        final int strLen = str.length();
8885        final int[] newCodePoints = new int[strLen]; // cannot be longer than the char array
8886        int outOffset = 0;
8887        for (int i = 0; i < strLen; ) {
8888            final int oldCodepoint = str.codePointAt(i);
8889            final int newCodePoint;
8890            if (Character.isUpperCase(oldCodepoint) || Character.isTitleCase(oldCodepoint)) {
8891                newCodePoint = Character.toLowerCase(oldCodepoint);
8892            } else if (Character.isLowerCase(oldCodepoint)) {
8893                newCodePoint = Character.toUpperCase(oldCodepoint);
8894            } else {
8895                newCodePoint = oldCodepoint;
8896            }
8897            newCodePoints[outOffset++] = newCodePoint;
8898            i += Character.charCount(newCodePoint);
8899         }
8900        return new String(newCodePoints, 0, outOffset);
8901    }
8902
8903    /**
8904     * Converts a {@link CharSequence} into an array of code points.
8905     *
8906     * <p>Valid pairs of surrogate code units will be converted into a single supplementary
8907     * code point. Isolated surrogate code units (i.e. a high surrogate not followed by a low surrogate or
8908     * a low surrogate not preceded by a high surrogate) will be returned as-is.</p>
8909     *
8910     * <pre>
8911     * StringUtils.toCodePoints(null)   =  null
8912     * StringUtils.toCodePoints("")     =  []  // empty array
8913     * </pre>
8914     *
8915     * @param cs the character sequence to convert
8916     * @return an array of code points
8917     * @since 3.6
8918     */
8919    public static int[] toCodePoints(final CharSequence cs) {
8920        if (cs == null) {
8921            return null;
8922        }
8923        if (cs.length() == 0) {
8924            return ArrayUtils.EMPTY_INT_ARRAY;
8925        }
8926
8927        final String s = cs.toString();
8928        final int[] result = new int[s.codePointCount(0, s.length())];
8929        int index = 0;
8930        for (int i = 0; i < result.length; i++) {
8931            result[i] = s.codePointAt(index);
8932            index += Character.charCount(result[i]);
8933        }
8934        return result;
8935    }
8936
8937    /**
8938     * Converts a {@code byte[]} to a String using the specified character encoding.
8939     *
8940     * @param bytes
8941     *            the byte array to read from
8942     * @param charset
8943     *            the encoding to use, if null then use the platform default
8944     * @return a new String
8945     * @throws NullPointerException
8946     *             if {@code bytes} is null
8947     * @since 3.2
8948     * @since 3.3 No longer throws {@link UnsupportedEncodingException}.
8949     */
8950    public static String toEncodedString(final byte[] bytes, final Charset charset) {
8951        return new String(bytes, Charsets.toCharset(charset));
8952    }
8953
8954    /**
8955     * Converts the given source String as a lower-case using the {@link Locale#ROOT} locale in a null-safe manner.
8956     *
8957     * @param source A source String or null.
8958     * @return the given source String as a lower-case using the {@link Locale#ROOT} locale or null.
8959     * @since 3.10
8960     */
8961    public static String toRootLowerCase(final String source) {
8962        return source == null ? null : source.toLowerCase(Locale.ROOT);
8963    }
8964
8965    /**
8966     * Converts the given source String as a upper-case using the {@link Locale#ROOT} locale in a null-safe manner.
8967     *
8968     * @param source A source String or null.
8969     * @return the given source String as a upper-case using the {@link Locale#ROOT} locale or null.
8970     * @since 3.10
8971     */
8972    public static String toRootUpperCase(final String source) {
8973        return source == null ? null : source.toUpperCase(Locale.ROOT);
8974    }
8975
8976    /**
8977     * Converts a {@code byte[]} to a String using the specified character encoding.
8978     *
8979     * @param bytes
8980     *            the byte array to read from
8981     * @param charsetName
8982     *            the encoding to use, if null then use the platform default
8983     * @return a new String
8984     * @throws UnsupportedEncodingException
8985     *             If the named charset is not supported
8986     * @throws NullPointerException
8987     *             if the input is null
8988     * @deprecated use {@link StringUtils#toEncodedString(byte[], Charset)} instead of String constants in your code
8989     * @since 3.1
8990     */
8991    @Deprecated
8992    public static String toString(final byte[] bytes, final String charsetName) throws UnsupportedEncodingException {
8993        return new String(bytes, Charsets.toCharset(charsetName));
8994    }
8995
8996    private static String toStringOrEmpty(final Object obj) {
8997        return Objects.toString(obj, EMPTY);
8998    }
8999
9000    /**
9001     * Removes control characters (char &lt;= 32) from both
9002     * ends of this String, handling {@code null} by returning
9003     * {@code null}.
9004     *
9005     * <p>The String is trimmed using {@link String#trim()}.
9006     * Trim removes start and end characters &lt;= 32.
9007     * To strip whitespace use {@link #strip(String)}.</p>
9008     *
9009     * <p>To trim your choice of characters, use the
9010     * {@link #strip(String, String)} methods.</p>
9011     *
9012     * <pre>
9013     * StringUtils.trim(null)          = null
9014     * StringUtils.trim("")            = ""
9015     * StringUtils.trim("     ")       = ""
9016     * StringUtils.trim("abc")         = "abc"
9017     * StringUtils.trim("    abc    ") = "abc"
9018     * </pre>
9019     *
9020     * @param str  the String to be trimmed, may be null
9021     * @return the trimmed string, {@code null} if null String input
9022     */
9023    public static String trim(final String str) {
9024        return str == null ? null : str.trim();
9025    }
9026
9027    /**
9028     * Removes control characters (char &lt;= 32) from both
9029     * ends of this String returning an empty String ("") if the String
9030     * is empty ("") after the trim or if it is {@code null}.
9031     *
9032     * <p>The String is trimmed using {@link String#trim()}.
9033     * Trim removes start and end characters &lt;= 32.
9034     * To strip whitespace use {@link #stripToEmpty(String)}.
9035     *
9036     * <pre>
9037     * StringUtils.trimToEmpty(null)          = ""
9038     * StringUtils.trimToEmpty("")            = ""
9039     * StringUtils.trimToEmpty("     ")       = ""
9040     * StringUtils.trimToEmpty("abc")         = "abc"
9041     * StringUtils.trimToEmpty("    abc    ") = "abc"
9042     * </pre>
9043     *
9044     * @param str  the String to be trimmed, may be null
9045     * @return the trimmed String, or an empty String if {@code null} input
9046     * @since 2.0
9047     */
9048    public static String trimToEmpty(final String str) {
9049        return str == null ? EMPTY : str.trim();
9050    }
9051
9052    /**
9053     * Removes control characters (char &lt;= 32) from both
9054     * ends of this String returning {@code null} if the String is
9055     * empty ("") after the trim or if it is {@code null}.
9056     *
9057     * <p>The String is trimmed using {@link String#trim()}.
9058     * Trim removes start and end characters &lt;= 32.
9059     * To strip whitespace use {@link #stripToNull(String)}.
9060     *
9061     * <pre>
9062     * StringUtils.trimToNull(null)          = null
9063     * StringUtils.trimToNull("")            = null
9064     * StringUtils.trimToNull("     ")       = null
9065     * StringUtils.trimToNull("abc")         = "abc"
9066     * StringUtils.trimToNull("    abc    ") = "abc"
9067     * </pre>
9068     *
9069     * @param str  the String to be trimmed, may be null
9070     * @return the trimmed String,
9071     *  {@code null} if only chars &lt;= 32, empty or null String input
9072     * @since 2.0
9073     */
9074    public static String trimToNull(final String str) {
9075        final String ts = trim(str);
9076        return isEmpty(ts) ? null : ts;
9077    }
9078
9079    /**
9080     * Truncates a String. This will turn
9081     * "Now is the time for all good men" into "Now is the time for".
9082     *
9083     * <p>Specifically:</p>
9084     * <ul>
9085     *   <li>If {@code str} is less than {@code maxWidth} characters
9086     *       long, return it.</li>
9087     *   <li>Else truncate it to {@code substring(str, 0, maxWidth)}.</li>
9088     *   <li>If {@code maxWidth} is less than {@code 0}, throw an
9089     *       {@link IllegalArgumentException}.</li>
9090     *   <li>In no case will it return a String of length greater than
9091     *       {@code maxWidth}.</li>
9092     * </ul>
9093     *
9094     * <pre>
9095     * StringUtils.truncate(null, 0)       = null
9096     * StringUtils.truncate(null, 2)       = null
9097     * StringUtils.truncate("", 4)         = ""
9098     * StringUtils.truncate("abcdefg", 4)  = "abcd"
9099     * StringUtils.truncate("abcdefg", 6)  = "abcdef"
9100     * StringUtils.truncate("abcdefg", 7)  = "abcdefg"
9101     * StringUtils.truncate("abcdefg", 8)  = "abcdefg"
9102     * StringUtils.truncate("abcdefg", -1) = throws an IllegalArgumentException
9103     * </pre>
9104     *
9105     * @param str  the String to truncate, may be null
9106     * @param maxWidth  maximum length of result String, must be positive
9107     * @return truncated String, {@code null} if null String input
9108     * @throws IllegalArgumentException If {@code maxWidth} is less than {@code 0}
9109     * @since 3.5
9110     */
9111    public static String truncate(final String str, final int maxWidth) {
9112        return truncate(str, 0, maxWidth);
9113    }
9114
9115    /**
9116     * Truncates a String. This will turn
9117     * "Now is the time for all good men" into "is the time for all".
9118     *
9119     * <p>Works like {@code truncate(String, int)}, but allows you to specify
9120     * a "left edge" offset.
9121     *
9122     * <p>Specifically:</p>
9123     * <ul>
9124     *   <li>If {@code str} is less than {@code maxWidth} characters
9125     *       long, return it.</li>
9126     *   <li>Else truncate it to {@code substring(str, offset, maxWidth)}.</li>
9127     *   <li>If {@code maxWidth} is less than {@code 0}, throw an
9128     *       {@link IllegalArgumentException}.</li>
9129     *   <li>If {@code offset} is less than {@code 0}, throw an
9130     *       {@link IllegalArgumentException}.</li>
9131     *   <li>In no case will it return a String of length greater than
9132     *       {@code maxWidth}.</li>
9133     * </ul>
9134     *
9135     * <pre>
9136     * StringUtils.truncate(null, 0, 0) = null
9137     * StringUtils.truncate(null, 2, 4) = null
9138     * StringUtils.truncate("", 0, 10) = ""
9139     * StringUtils.truncate("", 2, 10) = ""
9140     * StringUtils.truncate("abcdefghij", 0, 3) = "abc"
9141     * StringUtils.truncate("abcdefghij", 5, 6) = "fghij"
9142     * StringUtils.truncate("raspberry peach", 10, 15) = "peach"
9143     * StringUtils.truncate("abcdefghijklmno", 0, 10) = "abcdefghij"
9144     * StringUtils.truncate("abcdefghijklmno", -1, 10) = throws an IllegalArgumentException
9145     * StringUtils.truncate("abcdefghijklmno", Integer.MIN_VALUE, 10) = throws an IllegalArgumentException
9146     * StringUtils.truncate("abcdefghijklmno", Integer.MIN_VALUE, Integer.MAX_VALUE) = throws an IllegalArgumentException
9147     * StringUtils.truncate("abcdefghijklmno", 0, Integer.MAX_VALUE) = "abcdefghijklmno"
9148     * StringUtils.truncate("abcdefghijklmno", 1, 10) = "bcdefghijk"
9149     * StringUtils.truncate("abcdefghijklmno", 2, 10) = "cdefghijkl"
9150     * StringUtils.truncate("abcdefghijklmno", 3, 10) = "defghijklm"
9151     * StringUtils.truncate("abcdefghijklmno", 4, 10) = "efghijklmn"
9152     * StringUtils.truncate("abcdefghijklmno", 5, 10) = "fghijklmno"
9153     * StringUtils.truncate("abcdefghijklmno", 5, 5) = "fghij"
9154     * StringUtils.truncate("abcdefghijklmno", 5, 3) = "fgh"
9155     * StringUtils.truncate("abcdefghijklmno", 10, 3) = "klm"
9156     * StringUtils.truncate("abcdefghijklmno", 10, Integer.MAX_VALUE) = "klmno"
9157     * StringUtils.truncate("abcdefghijklmno", 13, 1) = "n"
9158     * StringUtils.truncate("abcdefghijklmno", 13, Integer.MAX_VALUE) = "no"
9159     * StringUtils.truncate("abcdefghijklmno", 14, 1) = "o"
9160     * StringUtils.truncate("abcdefghijklmno", 14, Integer.MAX_VALUE) = "o"
9161     * StringUtils.truncate("abcdefghijklmno", 15, 1) = ""
9162     * StringUtils.truncate("abcdefghijklmno", 15, Integer.MAX_VALUE) = ""
9163     * StringUtils.truncate("abcdefghijklmno", Integer.MAX_VALUE, Integer.MAX_VALUE) = ""
9164     * StringUtils.truncate("abcdefghij", 3, -1) = throws an IllegalArgumentException
9165     * StringUtils.truncate("abcdefghij", -2, 4) = throws an IllegalArgumentException
9166     * </pre>
9167     *
9168     * @param str  the String to truncate, may be null
9169     * @param offset  left edge of source String
9170     * @param maxWidth  maximum length of result String, must be positive
9171     * @return truncated String, {@code null} if null String input
9172     * @throws IllegalArgumentException If {@code offset} or {@code maxWidth} is less than {@code 0}
9173     * @since 3.5
9174     */
9175    public static String truncate(final String str, final int offset, final int maxWidth) {
9176        if (offset < 0) {
9177            throw new IllegalArgumentException("offset cannot be negative");
9178        }
9179        if (maxWidth < 0) {
9180            throw new IllegalArgumentException("maxWith cannot be negative");
9181        }
9182        if (str == null) {
9183            return null;
9184        }
9185        if (offset > str.length()) {
9186            return EMPTY;
9187        }
9188        if (str.length() > maxWidth) {
9189            final int ix = Math.min(offset + maxWidth, str.length());
9190            return str.substring(offset, ix);
9191        }
9192        return str.substring(offset);
9193    }
9194
9195    /**
9196     * Uncapitalizes a String, changing the first character to lower case as
9197     * per {@link Character#toLowerCase(int)}. No other characters are changed.
9198     *
9199     * <p>For a word based algorithm, see {@link org.apache.commons.text.WordUtils#uncapitalize(String)}.
9200     * A {@code null} input String returns {@code null}.</p>
9201     *
9202     * <pre>
9203     * StringUtils.uncapitalize(null)  = null
9204     * StringUtils.uncapitalize("")    = ""
9205     * StringUtils.uncapitalize("cat") = "cat"
9206     * StringUtils.uncapitalize("Cat") = "cat"
9207     * StringUtils.uncapitalize("CAT") = "cAT"
9208     * </pre>
9209     *
9210     * @param str the String to uncapitalize, may be null
9211     * @return the uncapitalized String, {@code null} if null String input
9212     * @see org.apache.commons.text.WordUtils#uncapitalize(String)
9213     * @see #capitalize(String)
9214     * @since 2.0
9215     */
9216    public static String uncapitalize(final String str) {
9217        final int strLen = length(str);
9218        if (strLen == 0) {
9219            return str;
9220        }
9221
9222        final int firstCodePoint = str.codePointAt(0);
9223        final int newCodePoint = Character.toLowerCase(firstCodePoint);
9224        if (firstCodePoint == newCodePoint) {
9225            // already capitalized
9226            return str;
9227        }
9228
9229        final int[] newCodePoints = new int[strLen]; // cannot be longer than the char array
9230        int outOffset = 0;
9231        newCodePoints[outOffset++] = newCodePoint; // copy the first code point
9232        for (int inOffset = Character.charCount(firstCodePoint); inOffset < strLen; ) {
9233            final int codePoint = str.codePointAt(inOffset);
9234            newCodePoints[outOffset++] = codePoint; // copy the remaining ones
9235            inOffset += Character.charCount(codePoint);
9236         }
9237        return new String(newCodePoints, 0, outOffset);
9238    }
9239
9240    /**
9241     * Unwraps a given string from a character.
9242     *
9243     * <pre>
9244     * StringUtils.unwrap(null, null)         = null
9245     * StringUtils.unwrap(null, '\0')         = null
9246     * StringUtils.unwrap(null, '1')          = null
9247     * StringUtils.unwrap("a", 'a')           = "a"
9248     * StringUtils.unwrap("aa", 'a')           = ""
9249     * StringUtils.unwrap("\'abc\'", '\'')    = "abc"
9250     * StringUtils.unwrap("AABabcBAA", 'A')   = "ABabcBA"
9251     * StringUtils.unwrap("A", '#')           = "A"
9252     * StringUtils.unwrap("#A", '#')          = "#A"
9253     * StringUtils.unwrap("A#", '#')          = "A#"
9254     * </pre>
9255     *
9256     * @param str
9257     *          the String to be unwrapped, can be null
9258     * @param wrapChar
9259     *          the character used to unwrap
9260     * @return unwrapped String or the original string
9261     *          if it is not quoted properly with the wrapChar
9262     * @since 3.6
9263     */
9264    public static String unwrap(final String str, final char wrapChar) {
9265        if (isEmpty(str) || wrapChar == CharUtils.NUL || str.length() == 1) {
9266            return str;
9267        }
9268
9269        if (str.charAt(0) == wrapChar && str.charAt(str.length() - 1) == wrapChar) {
9270            final int startIndex = 0;
9271            final int endIndex = str.length() - 1;
9272
9273            return str.substring(startIndex + 1, endIndex);
9274        }
9275
9276        return str;
9277    }
9278
9279    /**
9280     * Unwraps a given string from another string.
9281     *
9282     * <pre>
9283     * StringUtils.unwrap(null, null)         = null
9284     * StringUtils.unwrap(null, "")           = null
9285     * StringUtils.unwrap(null, "1")          = null
9286     * StringUtils.unwrap("a", "a")           = "a"
9287     * StringUtils.unwrap("aa", "a")          = ""
9288     * StringUtils.unwrap("\'abc\'", "\'")    = "abc"
9289     * StringUtils.unwrap("\"abc\"", "\"")    = "abc"
9290     * StringUtils.unwrap("AABabcBAA", "AA")  = "BabcB"
9291     * StringUtils.unwrap("A", "#")           = "A"
9292     * StringUtils.unwrap("#A", "#")          = "#A"
9293     * StringUtils.unwrap("A#", "#")          = "A#"
9294     * </pre>
9295     *
9296     * @param str
9297     *          the String to be unwrapped, can be null
9298     * @param wrapToken
9299     *          the String used to unwrap
9300     * @return unwrapped String or the original string
9301     *          if it is not quoted properly with the wrapToken
9302     * @since 3.6
9303     */
9304    public static String unwrap(final String str, final String wrapToken) {
9305        if (isEmpty(str) || isEmpty(wrapToken) || str.length() < 2 * wrapToken.length()) {
9306            return str;
9307        }
9308
9309        if (startsWith(str, wrapToken) && endsWith(str, wrapToken)) {
9310            return str.substring(wrapToken.length(), str.lastIndexOf(wrapToken));
9311        }
9312
9313        return str;
9314    }
9315
9316    /**
9317     * Converts a String to upper case as per {@link String#toUpperCase()}.
9318     *
9319     * <p>A {@code null} input String returns {@code null}.</p>
9320     *
9321     * <pre>
9322     * StringUtils.upperCase(null)  = null
9323     * StringUtils.upperCase("")    = ""
9324     * StringUtils.upperCase("aBc") = "ABC"
9325     * </pre>
9326     *
9327     * <p><strong>Note:</strong> As described in the documentation for {@link String#toUpperCase()},
9328     * the result of this method is affected by the current locale.
9329     * For platform-independent case transformations, the method {@link #upperCase(String, Locale)}
9330     * should be used with a specific locale (e.g. {@link Locale#ENGLISH}).</p>
9331     *
9332     * @param str  the String to upper case, may be null
9333     * @return the upper-cased String, {@code null} if null String input
9334     */
9335    public static String upperCase(final String str) {
9336        if (str == null) {
9337            return null;
9338        }
9339        return str.toUpperCase();
9340    }
9341
9342    /**
9343     * Converts a String to upper case as per {@link String#toUpperCase(Locale)}.
9344     *
9345     * <p>A {@code null} input String returns {@code null}.</p>
9346     *
9347     * <pre>
9348     * StringUtils.upperCase(null, Locale.ENGLISH)  = null
9349     * StringUtils.upperCase("", Locale.ENGLISH)    = ""
9350     * StringUtils.upperCase("aBc", Locale.ENGLISH) = "ABC"
9351     * </pre>
9352     *
9353     * @param str  the String to upper case, may be null
9354     * @param locale  the locale that defines the case transformation rules, must not be null
9355     * @return the upper-cased String, {@code null} if null String input
9356     * @since 2.5
9357     */
9358    public static String upperCase(final String str, final Locale locale) {
9359        if (str == null) {
9360            return null;
9361        }
9362        return str.toUpperCase(LocaleUtils.toLocale(locale));
9363    }
9364
9365    /**
9366     * Returns the string representation of the {@code char} array or null.
9367     *
9368     * @param value the character array.
9369     * @return a String or null
9370     * @see String#valueOf(char[])
9371     * @since 3.9
9372     */
9373    public static String valueOf(final char[] value) {
9374        return value == null ? null : String.valueOf(value);
9375    }
9376
9377    /**
9378     * Wraps a string with a char.
9379     *
9380     * <pre>
9381     * StringUtils.wrap(null, *)        = null
9382     * StringUtils.wrap("", *)          = ""
9383     * StringUtils.wrap("ab", '\0')     = "ab"
9384     * StringUtils.wrap("ab", 'x')      = "xabx"
9385     * StringUtils.wrap("ab", '\'')     = "'ab'"
9386     * StringUtils.wrap("\"ab\"", '\"') = "\"\"ab\"\""
9387     * </pre>
9388     *
9389     * @param str
9390     *            the string to be wrapped, may be {@code null}
9391     * @param wrapWith
9392     *            the char that will wrap {@code str}
9393     * @return the wrapped string, or {@code null} if {@code str==null}
9394     * @since 3.4
9395     */
9396    public static String wrap(final String str, final char wrapWith) {
9397
9398        if (isEmpty(str) || wrapWith == CharUtils.NUL) {
9399            return str;
9400        }
9401
9402        return wrapWith + str + wrapWith;
9403    }
9404
9405    /**
9406     * Wraps a String with another String.
9407     *
9408     * <p>
9409     * A {@code null} input String returns {@code null}.
9410     * </p>
9411     *
9412     * <pre>
9413     * StringUtils.wrap(null, *)         = null
9414     * StringUtils.wrap("", *)           = ""
9415     * StringUtils.wrap("ab", null)      = "ab"
9416     * StringUtils.wrap("ab", "x")       = "xabx"
9417     * StringUtils.wrap("ab", "\"")      = "\"ab\""
9418     * StringUtils.wrap("\"ab\"", "\"")  = "\"\"ab\"\""
9419     * StringUtils.wrap("ab", "'")       = "'ab'"
9420     * StringUtils.wrap("'abcd'", "'")   = "''abcd''"
9421     * StringUtils.wrap("\"abcd\"", "'") = "'\"abcd\"'"
9422     * StringUtils.wrap("'abcd'", "\"")  = "\"'abcd'\""
9423     * </pre>
9424     *
9425     * @param str
9426     *            the String to be wrapper, may be null
9427     * @param wrapWith
9428     *            the String that will wrap str
9429     * @return wrapped String, {@code null} if null String input
9430     * @since 3.4
9431     */
9432    public static String wrap(final String str, final String wrapWith) {
9433
9434        if (isEmpty(str) || isEmpty(wrapWith)) {
9435            return str;
9436        }
9437
9438        return wrapWith.concat(str).concat(wrapWith);
9439    }
9440
9441    /**
9442     * Wraps a string with a char if that char is missing from the start or end of the given string.
9443     *
9444     * <p>A new {@link String} will not be created if {@code str} is already wrapped.</p>
9445     *
9446     * <pre>
9447     * StringUtils.wrapIfMissing(null, *)        = null
9448     * StringUtils.wrapIfMissing("", *)          = ""
9449     * StringUtils.wrapIfMissing("ab", '\0')     = "ab"
9450     * StringUtils.wrapIfMissing("ab", 'x')      = "xabx"
9451     * StringUtils.wrapIfMissing("ab", '\'')     = "'ab'"
9452     * StringUtils.wrapIfMissing("\"ab\"", '\"') = "\"ab\""
9453     * StringUtils.wrapIfMissing("/", '/')  = "/"
9454     * StringUtils.wrapIfMissing("a/b/c", '/')  = "/a/b/c/"
9455     * StringUtils.wrapIfMissing("/a/b/c", '/')  = "/a/b/c/"
9456     * StringUtils.wrapIfMissing("a/b/c/", '/')  = "/a/b/c/"
9457     * </pre>
9458     *
9459     * @param str
9460     *            the string to be wrapped, may be {@code null}
9461     * @param wrapWith
9462     *            the char that will wrap {@code str}
9463     * @return the wrapped string, or {@code null} if {@code str==null}
9464     * @since 3.5
9465     */
9466    public static String wrapIfMissing(final String str, final char wrapWith) {
9467        if (isEmpty(str) || wrapWith == CharUtils.NUL) {
9468            return str;
9469        }
9470        final boolean wrapStart = str.charAt(0) != wrapWith;
9471        final boolean wrapEnd = str.charAt(str.length() - 1) != wrapWith;
9472        if (!wrapStart && !wrapEnd) {
9473            return str;
9474        }
9475
9476        final StringBuilder builder = new StringBuilder(str.length() + 2);
9477        if (wrapStart) {
9478            builder.append(wrapWith);
9479        }
9480        builder.append(str);
9481        if (wrapEnd) {
9482            builder.append(wrapWith);
9483        }
9484        return builder.toString();
9485    }
9486
9487    /**
9488     * Wraps a string with a string if that string is missing from the start or end of the given string.
9489     *
9490     * <p>A new {@link String} will not be created if {@code str} is already wrapped.</p>
9491     *
9492     * <pre>
9493     * StringUtils.wrapIfMissing(null, *)         = null
9494     * StringUtils.wrapIfMissing("", *)           = ""
9495     * StringUtils.wrapIfMissing("ab", null)      = "ab"
9496     * StringUtils.wrapIfMissing("ab", "x")       = "xabx"
9497     * StringUtils.wrapIfMissing("ab", "\"")      = "\"ab\""
9498     * StringUtils.wrapIfMissing("\"ab\"", "\"")  = "\"ab\""
9499     * StringUtils.wrapIfMissing("ab", "'")       = "'ab'"
9500     * StringUtils.wrapIfMissing("'abcd'", "'")   = "'abcd'"
9501     * StringUtils.wrapIfMissing("\"abcd\"", "'") = "'\"abcd\"'"
9502     * StringUtils.wrapIfMissing("'abcd'", "\"")  = "\"'abcd'\""
9503     * StringUtils.wrapIfMissing("/", "/")  = "/"
9504     * StringUtils.wrapIfMissing("a/b/c", "/")  = "/a/b/c/"
9505     * StringUtils.wrapIfMissing("/a/b/c", "/")  = "/a/b/c/"
9506     * StringUtils.wrapIfMissing("a/b/c/", "/")  = "/a/b/c/"
9507     * </pre>
9508     *
9509     * @param str
9510     *            the string to be wrapped, may be {@code null}
9511     * @param wrapWith
9512     *            the string that will wrap {@code str}
9513     * @return the wrapped string, or {@code null} if {@code str==null}
9514     * @since 3.5
9515     */
9516    public static String wrapIfMissing(final String str, final String wrapWith) {
9517        if (isEmpty(str) || isEmpty(wrapWith)) {
9518            return str;
9519        }
9520
9521        final boolean wrapStart = !str.startsWith(wrapWith);
9522        final boolean wrapEnd = !str.endsWith(wrapWith);
9523        if (!wrapStart && !wrapEnd) {
9524            return str;
9525        }
9526
9527        final StringBuilder builder = new StringBuilder(str.length() + wrapWith.length() + wrapWith.length());
9528        if (wrapStart) {
9529            builder.append(wrapWith);
9530        }
9531        builder.append(str);
9532        if (wrapEnd) {
9533            builder.append(wrapWith);
9534        }
9535        return builder.toString();
9536    }
9537
9538    /**
9539     * {@link StringUtils} instances should NOT be constructed in
9540     * standard programming. Instead, the class should be used as
9541     * {@code StringUtils.trim(" foo ");}.
9542     *
9543     * <p>This constructor is public to permit tools that require a JavaBean
9544     * instance to operate.</p>
9545     */
9546    public StringUtils() {
9547    }
9548
9549}