uk.ac.starlink.table
Class RandomRowSequence

java.lang.Object
  |
  +--uk.ac.starlink.table.RandomRowSequence
All Implemented Interfaces:
RowSequence

public class RandomRowSequence
extends Object
implements RowSequence

An implementation of RowSequence which obtains its data from a random-access StarTable object.


Constructor Summary
RandomRowSequence(StarTable startab)
          Constructs a RowSequence from a StarTable which must offer random access and know its number of rows.
 
Method Summary
 void close()
          Indicates that this sequence will not be required any more.
 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 hasNext()
          Indicates whether this table contains any more rows after the current one.
 void next()
          Advances the current row to the next one.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

RandomRowSequence

public RandomRowSequence(StarTable startab)
Constructs a RowSequence from a StarTable which must offer random access and know its number of rows.

Parameters:
startab - the StarTable object providing the data
Throws:
IllegalArgumentException - if startab.isRandom()==false or startab.getRowCount()<0
Method Detail

hasNext

public boolean hasNext()
Description copied from interface: RowSequence
Indicates whether this table contains any more rows after the current one.

Specified by:
hasNext in interface RowSequence
Returns:
true iff another row exists

next

public void next()
Description copied from interface: RowSequence
Advances the current row to the next one. 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. An unchecked exception such as NoSuchElementException will be thrown if RowSequence.hasNext() returns false.

Specified by:
next in interface RowSequence

getRow

public Object[] getRow()
                throws 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 interface RowSequence
Returns:
an array of the objects in each cell in row irow
Throws:
IOException - if there is an error reading the data

getCell

public Object getCell(int icol)
               throws 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 interface RowSequence
Returns:
the contents of cell icol in the current row
Throws:
IOException - if there is an error reading the data

close

public void close()
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 a close is undefined.

Specified by:
close in interface RowSequence

Copyright © 2004 CLRC: Central Laboratory of the Research Councils. All rights reserved.