public abstract class DataModel<E>
extends java.lang.Object
implements java.lang.Iterable<E>
DataModel is an abstraction around arbitrary data binding
technologies that can be used to adapt a variety of data sources for use by Jakarta Server Faces components that
support per-row processing for their child components (such as UIData
.
The data collection underlying a DataModel
instance is modeled as a collection of row objects that can be
accessed by a zero-relative cursor (row index). The APIs provide mechanisms to position to a specified zero-relative
row index, and to retrieve an object that represents the data that corresponds to the current row index.
A concrete DataModel
instance is attached to a particular collection of underlying data by calling the
setWrappedData()
method. It can be detached from that underlying data collection by passing a
null
parameter to this method.
Concrete DataModel
implementations must provide a public zero-arguments constructor that calls
setWrappedData(null)
. A convenience constructor that takes a wrapped object of the appropriate type (and
passes it on via a call to setWrappedData()
, should also be provided.
Event listeners may be registered to receive notifications of when a new row index is selected.
Constructor and Description |
---|
DataModel() |
Modifier and Type | Method and Description |
---|---|
void |
addDataModelListener(DataModelListener listener)
Add a new
DataModelListener to the set interested in notifications from this DataModel . |
DataModelListener[] |
getDataModelListeners()
Return the set of
DataModelListener s interested in notifications from this DataModel . |
abstract int |
getRowCount()
Return the number of rows of data objects represented by this
DataModel . |
abstract E |
getRowData()
Return an object representing the data for the currently selected row index.
|
abstract int |
getRowIndex()
Return the zero-relative index of the currently selected row.
|
abstract java.lang.Object |
getWrappedData()
Return the object representing the data wrapped by this
DataModel , if any. |
abstract boolean |
isRowAvailable()
Return a flag indicating whether there is
rowData available at the current rowIndex . |
java.util.Iterator<E> |
iterator()
Return a read-only |
void |
removeDataModelListener(DataModelListener listener)
Remove an existing
DataModelListener from the set interested in notifications from this DataModel . |
abstract void |
setRowIndex(int rowIndex)
Set the zero-relative index of the currently selected row, or -1 to indicate that we are not positioned on a row.
|
abstract void |
setWrappedData(java.lang.Object data)
Set the object representing the data collection wrapped by this
DataModel . |
public abstract boolean isRowAvailable()
Return a flag indicating whether there is rowData
available at the current rowIndex
. If no
wrappedData
is available, return false
.
FacesException
- if an error occurs getting the row availabilitypublic abstract int getRowCount()
Return the number of rows of data objects represented by this DataModel
. If the number of rows is unknown, or
no wrappedData
is available, return -1.
DataModel
FacesException
- if an error occurs getting the row countpublic abstract E getRowData()
Return an object representing the data for the currently selected row index. If no wrappedData
is
available, return null
.
FacesException
- if an error occurs getting the row datajava.lang.IllegalArgumentException
- if now row data is available at the currently specified row indexpublic abstract int getRowIndex()
Return the zero-relative index of the currently selected row. If we are not currently positioned on a row, or no
wrappedData
is available, return -1.
FacesException
- if an error occurs getting the row indexpublic abstract void setRowIndex(int rowIndex)
Set the zero-relative index of the currently selected row, or -1 to indicate that we are not positioned on a row. It
is possible to set the row index at a value for which the underlying data collection does not contain any row data.
Therefore, callers may use the isRowAvailable()
method to detect whether row data will be available for
use by the getRowData()
method.
If there is no wrappedData
available when this method is called, the specified rowIndex
is
stored (and may be retrieved by a subsequent call to getRowData()
), but no event is sent. Otherwise, if
the currently selected row index is changed by this call, a DataModelEvent
will be sent to the
rowSelected()
method of all registered DataModelListener
s.
rowIndex
- The new zero-relative index (must be non-negative)FacesException
- if an error occurs setting the row indexjava.lang.IllegalArgumentException
- if rowIndex
is less than -1public abstract java.lang.Object getWrappedData()
Return the object representing the data wrapped by this DataModel
, if any.
Object
that this model wraps.public abstract void setWrappedData(java.lang.Object data)
Set the object representing the data collection wrapped by this DataModel
. If the specified data
is null
, detach this DataModel
from any previously wrapped data collection instead.
If data
is non-null
, the currently selected row index must be set to zero, and a
DataModelEvent
must be sent to the rowSelected()
method of all registered
DataModelListener
s indicating that this row is now selected.
data
- Data collection to be wrapped, or null
to detach from any previous data collectionjava.lang.ClassCastException
- if data
is not of the appropriate type for this DataModel
implementationpublic void addDataModelListener(DataModelListener listener)
Add a new DataModelListener
to the set interested in notifications from this DataModel
.
listener
- The new DataModelListener
to be registeredjava.lang.NullPointerException
- if listener
is null
public DataModelListener[] getDataModelListeners()
Return the set of DataModelListener
s interested in notifications from this DataModel
. If there are no
such listeners, an empty array is returned.
public void removeDataModelListener(DataModelListener listener)
Remove an existing DataModelListener
from the set interested in notifications from this DataModel
.
listener
- The old DataModelListener
to be deregisteredjava.lang.NullPointerException
- if listener
is null