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 advance(long nrows)
          Moves the current row forward by offset rows.
 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.
 long getRowIndex()
          Returns the index of the current row.
 boolean hasNext()
          Indicates whether this table contains any more rows after the current one.
 void next()
          Advances the current row by 1.
 
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()
          throws IOException
Description copied from interface: RowSequence
Advances the current row by 1. Since the initial value of the current row is -1, next must be called before current row data as accessed by the RowSequence.getCell(int) or RowSequence.getRow() methods are invoked.

Specified by:
next in interface RowSequence
Throws:
IOException - if there is some error in the positioning

advance

public void advance(long nrows)
             throws IOException
Description copied from interface: RowSequence
Moves the current row forward by offset rows.

Specified by:
advance in interface RowSequence
Parameters:
nrows - the number of rows to advance the current row by.
Throws:
IOException - if an attempt to advance beyond the end of the table is made, or if there is some other read error

getRowIndex

public long getRowIndex()
Description copied from interface: RowSequence
Returns the index of the current row. This starts off at -1 before the first invocation of next.

Specified by:
getRowIndex in interface RowSequence
Returns:
the index of the current row

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.

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().

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

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