public abstract class DataModel<E> extends Object implements 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 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 . |
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(Object data)
Set the object representing the data collection wrapped by this
DataModel . |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
forEach, spliterator
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 dataIllegalArgumentException
- 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 indexIllegalArgumentException
- if rowIndex
is less than -1public abstract Object getWrappedData()
Return the object representing the data wrapped by this
DataModel
, if any.
Object
that this model wraps.public abstract void setWrappedData(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 collectionClassCastException
- 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 registeredNullPointerException
- 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 deregisteredNullPointerException
- if listener
is null
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