uk.ac.starlink.table

Class ReaderRowSequence

java.lang.Object

uk.ac.starlink.table.ReaderRowSequence

All Implemented Interfaces:

Closeable, AutoCloseable, RowData, RowSequence, Sequence

public abstract class ReaderRowSequence
extends Object
implements RowSequence

Partial implementation of RowSequence suitable for subclassing by classes which can read a row at a time and don't know when the row stream will come to an end. Concrete subclasses have to implement the readRow() method. They may also want to override close().

Author:

Mark Taylor (Starlink)

Constructor Summary

Constructors

Constructor and Description
ReaderRowSequence()

Method Summary

Modifier and Type	Method and Description
void	close() The ReaderRowSequence implementation does nothing.
Object	getCell(int icol) Returns the contents of a cell in the current row.
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.
protected abstract Object[]	readRow() Acquires the next row of objects from the input stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ReaderRowSequence

public ReaderRowSequence()

Method Detail

readRow

protected abstract Object[] readRow()
                             throws IOException

Acquires the next row of objects from the input stream. When there are no more rows to read this method must return null; note it should not throw an exception to indicate this fact. Otherwise it must return an array of objects representing the row content for the next row.

Returns:

the next row, or null if there are no more

Throws:

IOException - if there is trouble reading the data

next

public boolean next()
             throws 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 the RowSequence.getCell(int) or RowSequence.getRow() methods.

Specified by:

next in interface RowSequence

Specified by:

next in interface Sequence

Returns:

true iff this sequence has been advanced to the next row

Throws:

IOException - if there is some error

getCell

public Object getCell(int icol)

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 interface RowData

Specified by:

getCell in interface RowSequence

Parameters:

icol - column index

Returns:

the contents of cell icol in the current row

getRow

public Object[] getRow()

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 interface RowData

Specified by:

getRow in interface RowSequence

Returns:

an array of the objects in each cell in row irow

close

public void close()
           throws IOException

The ReaderRowSequence implementation does nothing.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface RowSequence

Throws:

IOException