uk.ac.starlink.ttools
Class HeadTable

java.lang.Object
  |
  +--uk.ac.starlink.table.WrapperStarTable
        |
        +--uk.ac.starlink.ttools.HeadTable
All Implemented Interfaces:
StarTable

public class HeadTable
extends WrapperStarTable

Wrapper table implementation which only contains the first N rows of its base table.

Since:
7 Mar 2005

Field Summary
 
Fields inherited from class uk.ac.starlink.table.WrapperStarTable
baseTable
 
Constructor Summary
HeadTable(StarTable base, long nhead)
          Constructor.
 
Method Summary
 Object getCell(long irow, int icol)
          Returns the contents of a given table cell.
 Object[] getRow(long irow)
          Returns the contents of a given table row.
 long getRowCount()
          Returns the number of rows in this table, if known.
 RowSequence getRowSequence()
          Returns an object which can iterate over all the rows in the table sequentially.
 
Methods inherited from class uk.ac.starlink.table.WrapperStarTable
checkedLongToInt, getBaseTable, getColumnAuxDataInfos, getColumnCount, getColumnInfo, getName, getParameterByName, getParameters, getURL, isRandom, setName, setParameter, setURL
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

HeadTable

public HeadTable(StarTable base,
                 long nhead)
Constructor.

Parameters:
base - base table
nhead - number of rows at the head of the table to use
Method Detail

getRowCount

public long getRowCount()
Description copied from interface: StarTable
Returns the number of rows in this table, if known. If the number of rows cannot be (easily) determined, a value of -1 will be returned.

Specified by:
getRowCount in interface StarTable
Overrides:
getRowCount in class WrapperStarTable
Returns:
the number of rows, or -1

getCell

public Object getCell(long irow,
                      int icol)
               throws IOException
Description copied from interface: StarTable
Returns the contents of a given table cell. 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 StarTable
Overrides:
getCell in class WrapperStarTable
Parameters:
irow - the index of the cell's row
icol - the index of the cell's column
Returns:
the contents of this cell
Throws:
IOException - if there is an error reading the data

getRow

public Object[] getRow(long irow)
                throws IOException
Description copied from interface: StarTable
Returns the contents of a given table row. The returned value is equivalent to an array formed of all the objects returned by getCell(irow,icol) for all the columns icol in sequence.

Specified by:
getRow in interface StarTable
Overrides:
getRow in class WrapperStarTable
Parameters:
irow - the index of the row to retrieve
Returns:
an array of the objects in each cell in row irow
Throws:
IOException - if there is an error reading the data

getRowSequence

public RowSequence getRowSequence()
                           throws IOException
Description copied from interface: StarTable
Returns an object which can iterate over all the rows in the table sequentially.

Specified by:
getRowSequence in interface StarTable
Overrides:
getRowSequence in class WrapperStarTable
Returns:
an object providing sequential access to the table data
Throws:
IOException - if there is an error providing access

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