org.apache.tapestry5.internal.grid
Class NullDataSource

java.lang.Object
  extended by org.apache.tapestry5.internal.grid.NullDataSource
All Implemented Interfaces:
GridDataSource

public class NullDataSource
extends Object
implements GridDataSource

An implementation of GridDataSource used when the value null is provided as the source.


Constructor Summary
NullDataSource()
           
 
Method Summary
 int getAvailableRows()
          Returns the number of rows available in the data source.
 Class getRowType()
          Returns the type of value in the rows, or null if not known.
 Object getRowValue(int index)
          Returns the row value at the provided index.
 void prepare(int startIndex, int endIndex, List<SortConstraint> sortConstraints)
          Invoked to allow the source to prepare to present values.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

NullDataSource

public NullDataSource()
Method Detail

getAvailableRows

public int getAvailableRows()
Description copied from interface: GridDataSource
Returns the number of rows available in the data source.

Specified by:
getAvailableRows in interface GridDataSource

getRowType

public Class getRowType()
Description copied from interface: GridDataSource
Returns the type of value in the rows, or null if not known. This value is used to create a default BeanModel when no such model is explicitly provided.

Specified by:
getRowType in interface GridDataSource
Returns:
the row type, or null

prepare

public void prepare(int startIndex,
                    int endIndex,
                    List<SortConstraint> sortConstraints)
Description copied from interface: GridDataSource
Invoked to allow the source to prepare to present values. This gives the source a chance to pre-fetch data (when appropriate) and informs the source of the desired sort order. Sorting comes first, then extraction by range.

Specified by:
prepare in interface GridDataSource
Parameters:
startIndex - the starting index to be retrieved
endIndex - the ending index to be retrieved
sortConstraints - identify how data is to be sorted

getRowValue

public Object getRowValue(int index)
Description copied from interface: GridDataSource
Returns the row value at the provided index. This method will be invoked in sequential order. In rare instances, GridDataSource.getAvailableRows() may return a different number of rows than are actually available (i.e., the database was changed between calls to GridDataSource.getAvailableRows() and the call to GridDataSource.prepare(int, int, java.util.List)). In that case, this method should return null for any out-of-range indexes.

Specified by:
getRowValue in interface GridDataSource


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