Package org.apache.tapestry5.internal.grid

Class NullDataSource

java.lang.Object

org.apache.tapestry5.internal.grid.NullDataSource

All Implemented Interfaces:

GridDataSource

public class NullDataSource
extends java.lang.Object
implements GridDataSource

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

Constructor Summary

Constructors

Constructor	Description
NullDataSource()

Method Summary

Modifier and Type	Method	Description
int	getAvailableRows()	Returns the number of rows available in the data source.
java.lang.Class	getRowType()	Returns the type of value in the rows, or null if not known.
java.lang.Object	getRowValue(int index)	Returns the row value at the provided index.
void	prepare(int startIndex, int endIndex, java.util.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

Methods inherited from interface org.apache.tapestry5.grid.GridDataSource

getAvailableRows, isEmpty

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 java.lang.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,
                    java.util.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 java.lang.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