Package uk.ac.starlink.table
Interface RowSequence
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- All Superinterfaces:
java.lang.AutoCloseable
,java.io.Closeable
,RowData
,uk.ac.starlink.util.Sequence
- All Known Subinterfaces:
RowSplittable
- All Known Implementing Classes:
AccessRowSequence
,EmptyRowSequence
,IteratorRowSequence
,MappingRowSplittable
,OnceRowPipe
,ProgressRowSplittable
,RandomRowSplittable
,ReaderRowSequence
,SequentialRowSplittable
,WrapperRowSequence
public interface RowSequence extends java.io.Closeable, RowData, uk.ac.starlink.util.Sequence
Provides sequential access to the data in a table. The data is a sequence of rows which may be processed from the first to the last. A RowSequence iterates over the rows one at a time. It starts off positioned before the first row, so the next method must be invoked before the first row can be accessed.Typical usage might look like this:
RowSequence rseq = table.getRowSequence(); try { while ( rseq.next() ) { Object[] row = rseq.getRow(); ... } } finally { rseq.close(); }
A RowSequence cannot in general be expected to be used safely from multiple threads.
- Author:
- Mark Taylor (Starlink)
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Method Summary
All Methods Instance Methods Abstract 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.
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Method Detail
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next
boolean next() throws java.io.IOException
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 thegetCell(int)
orgetRow()
methods.- 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
java.lang.Object getCell(int icol) throws java.io.IOException
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).
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getRow
java.lang.Object[] getRow() throws java.io.IOException
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).
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close
void close() throws java.io.IOException
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
- Throws:
java.io.IOException
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