Class DataModel<E>
- All Implemented Interfaces:
Iterable<E>
- Direct Known Subclasses:
ArrayDataModel
,CollectionDataModel
,IterableDataModel
,ListDataModel
,ResultDataModel
,ResultSetDataModel
,ScalarDataModel
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.
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Constructor Summary
Constructors Constructor Description DataModel()
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Method Summary
Modifier and Type Method Description void
addDataModelListener(DataModelListener listener)
Add a newDataModelListener
to the set interested in notifications from thisDataModel
.DataModelListener[]
getDataModelListeners()
Return the set ofDataModelListener
s interested in notifications from thisDataModel
.abstract int
getRowCount()
Return the number of rows of data objects represented by thisDataModel
.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 thisDataModel
, if any.abstract boolean
isRowAvailable()
Return a flag indicating whether there isrowData
available at the currentrowIndex
.Iterator<E>
iterator()
Return a read-onlyIterator
over the row data for this model.void
removeDataModelListener(DataModelListener listener)
Remove an existingDataModelListener
from the set interested in notifications from thisDataModel
.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 thisDataModel
.
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Constructor Details
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DataModel
public DataModel()
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Method Details
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isRowAvailable
public abstract boolean isRowAvailable()Return a flag indicating whether there is
rowData
available at the currentrowIndex
. If nowrappedData
is available, returnfalse
.- Returns:
- true if and only if there is data available at the current index, false otherwise.
- Throws:
FacesException
- if an error occurs getting the row availability
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getRowCount
public abstract int getRowCount()Return the number of rows of data objects represented by this
DataModel
. If the number of rows is unknown, or nowrappedData
is available, return -1.- Returns:
- the number of rows of data represented by this
DataModel
- Throws:
FacesException
- if an error occurs getting the row count
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getRowData
Return an object representing the data for the currently selected row index. If no
wrappedData
is available, returnnull
.- Returns:
- an object representing the data for the currently selected row index
- Throws:
FacesException
- if an error occurs getting the row dataIllegalArgumentException
- if now row data is available at the currently specified row index
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getRowIndex
public 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.- Returns:
- the index of the currently selected row
- Throws:
FacesException
- if an error occurs getting the row index
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setRowIndex
public 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 thegetRowData()
method.If there is no
wrappedData
available when this method is called, the specifiedrowIndex
is stored (and may be retrieved by a subsequent call togetRowData()
), but no event is sent. Otherwise, if the currently selected row index is changed by this call, aDataModelEvent
will be sent to therowSelected()
method of all registeredDataModelListener
s.- Parameters:
rowIndex
- The new zero-relative index (must be non-negative)- Throws:
FacesException
- if an error occurs setting the row indexIllegalArgumentException
- ifrowIndex
is less than -1
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getWrappedData
Return the object representing the data wrapped by this
DataModel
, if any.- Returns:
- the
Object
that this model wraps.
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setWrappedData
Set the object representing the data collection wrapped by this
DataModel
. If the specifieddata
isnull
, detach thisDataModel
from any previously wrapped data collection instead.If
data
is non-null
, the currently selected row index must be set to zero, and aDataModelEvent
must be sent to therowSelected()
method of all registeredDataModelListener
s indicating that this row is now selected.- Parameters:
data
- Data collection to be wrapped, ornull
to detach from any previous data collection- Throws:
ClassCastException
- ifdata
is not of the appropriate type for thisDataModel
implementation
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addDataModelListener
Add a new
DataModelListener
to the set interested in notifications from thisDataModel
.- Parameters:
listener
- The newDataModelListener
to be registered- Throws:
NullPointerException
- iflistener
isnull
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getDataModelListeners
Return the set of
DataModelListener
s interested in notifications from thisDataModel
. If there are no such listeners, an empty array is returned.- Returns:
- the listeners for this instance, or an empty array
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removeDataModelListener
Remove an existing
DataModelListener
from the set interested in notifications from thisDataModel
.- Parameters:
listener
- The oldDataModelListener
to be deregistered- Throws:
NullPointerException
- iflistener
isnull
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iterator
Return a read-only
Iterator
over the row data for this model.
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