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package javax.faces.model;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import javax.faces.model.DataModel;
import javax.faces.model.DataModelEvent;
import javax.faces.model.DataModelListener;
import javax.faces.model.ListDataModel;
/**
* IterableDataModel is an
* implementation of {@link DataModel} that wraps an Iterable.
*
*
* This can be used to encapsulate nearly every collection type, including
* {@link Collection} derived types such as {@link List} and {@link Set}.
* As such this specific DataModel can be used instead of more specific
* DataModels like {@link ListDataModel} and {@link CollectionDataModel}.
*
*/
public class IterableDataModel extends DataModel {
/**
* The current row index.
*/
private int index = -1;
/**
* The iterable that this data model is primarily wrapping.
*/
private Iterable iterable;
/**
* A list that's optionally used to hold and cache data collected
* from the iterable that this data model is wrapping.
*/
private List list;
/**
* Construct a new {@link IterableDataModel} with no specified
* wrapped data.
*/
public IterableDataModel() {
this(null);
}
/**
* Construct a new {@link IterableDataModel} wrapping the specified
* iterable.
*
* @param iterable Iterable to be wrapped.
*/
public IterableDataModel(Iterable iterable) {
setWrappedData(iterable);
}
/**
* Return a flag indicating whether there is rowData
* available at the current rowIndex. If no
* wrappedData is available, return false.
*
* @throws javax.faces.FacesException if an error occurs getting the row availability
*/
@Override
public boolean isRowAvailable() {
return list != null && index >= 0 && index < list.size();
}
/**
* Return the number of rows of data objects represented by this
* {@link DataModel}. If the number of rows is unknown, or no
* wrappedData is available, return -1.
*
* @throws javax.faces.FacesException if an error occurs getting the row count
*/
@Override
public int getRowCount() {
if (list == null) {
return -1;
}
return list.size();
}
/**
* Return an object representing the data for the currenty selected
* row index. If no wrappedData is available, return
* null.
*
* @throws javax.faces.FacesException if an error occurs getting the row data
* @throws IllegalArgumentException if now row data is available
* at the currently specified row index
*/
@Override
public E getRowData() {
if (list == null) {
return null;
}
if (!isRowAvailable()) {
throw new IllegalArgumentException();
}
return list.get(index);
}
/**
* 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.
*
* @throws javax.faces.FacesException if an error occurs getting the row index
*/
@Override
public int getRowIndex() {
return index;
}
/**
* 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 {@link DataModelEvent} will be sent to the
* rowSelected() method of all registered
* {@link DataModelListener}s.
*
* @param rowIndex The new zero-relative index (must be non-negative)
*
* @throws javax.faces.FacesException if an error occurs setting the row index
* @throws IllegalArgumentException if rowIndex
* is less than -1
*/
@Override
public void setRowIndex(int rowIndex) {
if (rowIndex < -1) {
throw new IllegalArgumentException();
}
int oldRowIndex = index;
index = rowIndex;
if (list == null) {
return;
}
notifyListeners(oldRowIndex, rowIndex);
}
/**
* Return the object representing the data wrapped by this
* {@link DataModel}, if any.
*/
@Override
public Object getWrappedData() {
return iterable;
}
/**
* Set the object representing the data collection wrapped by this
* {@link DataModel}. If the specified data is
* null, detach this {@link 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 {@link DataModelEvent} must be sent
* to the rowSelected() method of all registered
* {@link DataModelListener}s indicating that this row is now selected.
*
* @param data Data collection to be wrapped, or null to
* detach from any previous data collection
*
* @throws ClassCastException if data is not of the
* appropriate type for this {@link DataModel} implementation
*/
@SuppressWarnings("unchecked")
@Override
public void setWrappedData(Object data) {
if (data == null) {
iterable = null;
list = null;
setRowIndex(-1);
} else {
iterable = (Iterable) data;
list = iterableToList(iterable);
setRowIndex(0);
}
}
/**
* Return an object representing the data for the currently selected
* row index. If either no wrappedData is available or if
* there is no rowDataavailable at the current rowIndex,
* return null.
*
* @return data for the currently selected row index, or null if there's no data
*/
private E getRowDataOrNull() {
if (isRowAvailable()) {
return getRowData();
}
return null;
}
/**
* Notifies all DataModelListeners
*
* @param oldRowIndex the previous index
* @param rowIndex The current zero-relative index (must be non-negative)
*/
private void notifyListeners(int oldRowIndex, int rowIndex) {
DataModelListener[] dataModelListeners = getDataModelListeners();
if (oldRowIndex != rowIndex && dataModelListeners != null) {
DataModelEvent dataModelEvent = new DataModelEvent(this, rowIndex, getRowDataOrNull());
for (DataModelListener dataModelListener : dataModelListeners) {
if (dataModelListener != null) {
dataModelListener.rowSelected(dataModelEvent);
}
}
}
}
/**
* Converts an iterable into a list.
*
* This method makes NO guarantee to whether changes to the source iterable are
* reflected in the returned list or not. For instance if the given iterable
* already is a list, it's returned directly.
*
* @param The generic iterable element type.
* @param iterable The iterable to be converted.
* @return The list representation of the given iterable, possibly the same instance as that iterable.
*/
private static List iterableToList(Iterable iterable) {
List list = null;
if (iterable instanceof List) {
list = (List) iterable;
} else if (iterable instanceof Collection) {
list = new ArrayList<>((Collection) iterable);
} else {
list = new ArrayList<>();
Iterator iterator = iterable.iterator();
while (iterator.hasNext()) {
list.add(iterator.next());
}
}
return list;
}
}