Class RandomRowSplittable
- java.lang.Object
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- uk.ac.starlink.table.RandomRowSplittable
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
,RowData
,RowSequence
,RowSplittable
,uk.ac.starlink.util.Sequence
,uk.ac.starlink.util.Splittable<RowSplittable>
public class RandomRowSplittable extends java.lang.Object implements RowSplittable
RowSplittable based on a RowAccess.- Since:
- 4 Aug 2020
- Author:
- Mark Taylor
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Constructor Summary
Constructors Constructor Description RandomRowSplittable(StarTable table)
Constructs a splittable for a given table.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
close()
Indicates that this sequence will not be required any more.java.lang.Object
getCell(int icol)
Returns the contents of a cell in the current row.java.lang.Object[]
getRow()
Returns the contents of the current table row, as an array with the same number of elements as there are columns in this table.boolean
next()
Attempts to advance the current row to the next one.java.util.function.LongSupplier
rowIndex()
Returns a supplier for the index of the row currently being processed, if possible.RandomRowSplittable
split()
long
splittableSize()
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Constructor Detail
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RandomRowSplittable
public RandomRowSplittable(StarTable table) throws java.io.IOException
Constructs a splittable for a given table.- Parameters:
table
- random-access table- Throws:
java.lang.UnsupportedOperationException
- if table is not random-accessjava.io.IOException
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Method Detail
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splittableSize
public long splittableSize()
- Specified by:
splittableSize
in interfaceuk.ac.starlink.util.Splittable<RowSplittable>
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split
public RandomRowSplittable split()
- Specified by:
split
in interfaceuk.ac.starlink.util.Splittable<RowSplittable>
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rowIndex
public java.util.function.LongSupplier rowIndex()
Description copied from interface:RowSplittable
Returns a supplier for the index of the row currently being processed, if possible. The row index is a global value; when accessing the first row of a top-level RowSplittable, the value returned by this supplier should be the first index in the table. But for objects resulting from splitting a top-level instance into sub-instances, the return value should reflect the index in the original sequence of rows; each index should be returned from only one of the splittables resulting from splitting a top-level instance.Typically, the row index will start at 0 and increment for each row, but the numbering may be different depending on the requirements of the implementation or usage.
Before the
RowSequence.next()
method has been called, the return value will be one less than the first row index. AfterRowSequence.next
has returned false, the value is undefined.Depending on the implementation, it may not be possible to determine the row index (for instance if the sequence is split into sub-splittables of unknown size). In such cases, this method returns null. The null-ness of the return value must be the same for all instances of the splittable hierarchy for a given sequence, so don't return a non-null value for the first splittable and then null values for some or all of its children.
- Specified by:
rowIndex
in interfaceRowSplittable
- Returns:
- supplier for the globally-referenced row index value of the current row of this sequence, or null
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next
public boolean next() throws java.io.IOException
Description copied from interface:RowSequence
Attempts to advance the current row to the next one. If true is returned the attempt has been successful, and if false is returned there are no more rows in this sequence. Since the initial position of a RowSequence is before the first row, this method must be called before current row data can be accessed using theRowSequence.getCell(int)
orRowSequence.getRow()
methods.- Specified by:
next
in interfaceRowSequence
- Specified by:
next
in interfaceuk.ac.starlink.util.Sequence
- Returns:
- true iff this sequence has been advanced to the next row
- Throws:
java.io.IOException
- if there is some error
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getCell
public java.lang.Object getCell(int icol) throws java.io.IOException
Description copied from interface:RowSequence
Returns the contents of a cell in the current row. The class of the returned object should be the same as, or a subclass of, the class returned by getColumnInfo(icol).getContentClass(). An unchecked exception will be thrown if there is no current row (next has not yet been called).- Specified by:
getCell
in interfaceRowData
- Specified by:
getCell
in interfaceRowSequence
- Parameters:
icol
- column index- Returns:
- the contents of cell icol in the current row
- Throws:
java.io.IOException
- if there is an error reading the data
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getRow
public java.lang.Object[] getRow() throws java.io.IOException
Description copied from interface:RowSequence
Returns the contents of the current table row, as an array with the same number of elements as there are columns in this table. An unchecked exception will be thrown if there is no current row (next has not yet been called).- Specified by:
getRow
in interfaceRowData
- Specified by:
getRow
in interfaceRowSequence
- Returns:
- an array of the objects in each cell in row irow
- Throws:
java.io.IOException
- if there is an error reading the data
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close
public void close() throws java.io.IOException
Description copied from interface:RowSequence
Indicates that this sequence will not be required any more. This should release resources associated with this object. The effect of calling any of the other methods following aclose
is undefined.- Specified by:
close
in interfacejava.lang.AutoCloseable
- Specified by:
close
in interfacejava.io.Closeable
- Specified by:
close
in interfaceRowSequence
- Throws:
java.io.IOException
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