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Class com.sun.java.swing.JList

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.Container
                   |
                   +----com.sun.java.swing.JComponent
                           |
                           +----com.sun.java.swing.JList

public class JList

extends JComponent

implements Accessible, Scrollable

// Create a JList that displays the strings in data[]
String[] data = {"one", "two", "free", "four"};
JList dataList = new JList(data);
// The value JList model property is an object that provides
// a read-only view of the data.  It was constructed automatically.
for(int i = 0; i < dataList.getModel().getSize(); i++) {
System.out.println(dataList.getModel().getElementAt(i));
}
// Create a JList that displays the superclass of JList.class.
//   We store the superclasses in a java.util.Vector.
Vector superClasses = new Vector();
Class rootClass = com.sun.java.swing.JList.class;
for(Class cls = rootClass; cls != null; cls = cls.getSuperclass()) {
superClasses.addElement(cls);
}
JList classList = new JList(superClasses);

JList doesn't support scrolling directly. To create a scrolling list you make the JList the viewport view of a JScrollPane, e.g.

JScrollPane scrollPane = new JScrollPane(dataList);
// Or in two steps:
JScrollPane scrollPane = new JScrollPane();
scrollPane.getViewport().setView(dataList);

By default JList supports single selection, i.e. zero or one index can be selected. The selection state is actually managed by a separate delegate object, an implementation of ListSelectionModel however JList provides convenient properties for managing the selection.

String[] data = {"one", "two", "free", "four"};
JList dataList = new JList(data);
dataList.setSelectedIndex(1);  // select "two"
dataList.getSelectedValue();   // returns "two"

The contents of a JList can be dynamic, i.e. the list elements can change value and the size of the list can change after the JList has been created. The JList observes changes in its model with a ListModelListener. A correct implementation of ListModel will notify it's listeners each time a change occurs. The changes are characterized by a ListModelEvent that simply identifies the range of List indices that have been modified, added, or removed. Simple dynamic content JList applications can use the DefaultListModel class to store list elements. This class implements the ListModel interfaces and provides all of the java.util.Vector API as well. Applications that need to provide custom ListModel implementations may want to subclass AbstractListModel, which provides basic ListModelListener support. For example:

// This list model has about 2^16 elements.  Enjoy scrolling.
ListModel bigData = new AbstractListModel() {
public int getSize() { return Short.MAX_VALUE; }
public Object getElementAt(int index) { return "Index " + index; }
};
JList bigDataList = new List(bigData);
// We don't want the JList implementation to compute the width 
// or height of all of the list cells, so we give it a String 
// that's as big as we'll need for any cell.  It uses this to 
// compute values for the fixedCellWidth and fixedCellHeight 
// properties.
bigDataList.setPrototypeCellValue("Index 1234567890");

JList uses a java.awt.Component, provided by a delegate called the cellRendererer, to paint the visible cells in the list. The cellRenderer component is used like a "rubber stamp" to paint each visible row. Each time the JList needs to paint a cell it asks the cellRenderer for the component, moves it into place with setBounds() and then draws it by calling its paint method. The default cellRenderer uses a JLabel component to render the string value of each component. You can substitute your own cellRenderer, e.g.:

// Display an icon and a string for each object in the list.
class MyCellRenderer extends JLabel implements ListCellRenderer {
final static ImageIcon longIcon = new ImageIcon("long.gif");
final static ImageIcon shortIcon = new ImageIcon("short.gif");
// This is the only method defined by ListCellRenderer.  We just
// reconfigure the Jlabel each time we're called.
public Component getListCellRendererComponent(
JList list,              
Object value,            // value to display
int index,               // cell index
boolean isSelected,      // is the cell selected
boolean cellHasFocus)    // the list and the cell have the focus
{
String s = value.toString();
setText(s);
setIcon((s.length > 10) ? longIcon : shortIcon);
return this;
}
}
String[] data = {"one", "two", "free", "four"};
JList dataList = new JList(data);
dataList.setCellRenderer(new MyCellRenderer());

JList doesn't provide any special support for handling doulble or triple (or N) mouse clicks however it's easy to handle them using a MouseListener. Just use the JList locationToIndex() method to determine what cell was clicked on. For example:

final JList list = new JList(dataModel);
MouseListener mouseListener = new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
if (e.getClickCount() == 2) {
int index = list.locationToIndex(e.getPoint());
System.out.println("Double clicked on Item " + index);
}
}
};
list.addMouseListener(mouseListener);

See Also:

ListModel, AbstractListModel, DefaultListModel, ListSelectionModel, DefaultListSelectionModel, ListCellRenderer

JList()

Constructs a JList with an empty model.

JList(ListModel)

Construct a JList that displays the elements in the specified, non-null model.

JList(Object[])

Construct a JList that displays the elements in the specified array.

JList(Vector)

Construct a JList that displays the elements in the specified Vector.

addListSelectionListener(ListSelectionListener)

Add a listener to the list that's notified each time a change to the selection occurs.

addSelectionInterval(int, int)

Set the selection to be the union of the specified interval with current selection.

clearSelection()

Clears the selection - after calling this method isSelectionEmpty() will return true.

createSelectionModel()

Returns an instance of DefaultListSelectionModel.

ensureIndexIsVisible(int)

If this JList is being displayed withing a JViewport and the specified cell isn't completely visible, scroll the viewport.

fireSelectionValueChanged(int, int, boolean)

This method notifies JList ListSelectionListeners that the selection model has changed.

getAccessibleAt(Point)

Returns the Accessible child contained at the local coordinate Point, if one exists.

getAccessibleChild(int)

Return the nth Accessible child of the object.

getAccessibleChildrenCount()

Returns the number of accessible children in the object.

getAccessibleRole()

Get the role of this object.

getAccessibleStateSet()

Get the state set of this object.

getAnchorSelectionIndex()

Returns the first index argument from the most recent addSelectionInterval or setSelectionInterval call.

getCellBounds(int, int)

Returns the bounds of the specified item in JList coordinates, null if index isn't valid.

getCellRenderer()

getFirstVisibleIndex()

Return the index of the cell in the upper left corner of the JList or -1 if nothing is visible or the list is empty.

getFixedCellHeight()

getFixedCellWidth()

getLastVisibleIndex()

Return the index of the cell in the lower right corner of the JList or -1 if nothing is visible or the list is empty.

getLeadSelectionIndex()

Returns the second index argument from the most recent addSelectionInterval or setSelectionInterval call.

getMaxSelectionIndex()

Returns the largest selected cell index.

getMinSelectionIndex()

Returns the smallest selected cell index.

getModel()

getPreferredScrollableViewportSize()

Compute the size of the viewport needed to display visibleRowCount rows.

getPrototypeCellValue()

getScrollableBlockIncrement(Rectangle, int, int)

getScrollableTracksViewportHeight()

If this JList is displayed in a JViewport, don't change its height when the viewports height changes.

getScrollableTracksViewportWidth()

If this JList is displayed in a JViewport, don't change its width when the viewports width changes.

getScrollableUnitIncrement(Rectangle, int, int)

If we're scrolling downwards (direction is greater than 0), and the first row is completely visible with respect to visibleRect, then return its height.

getSelectedIndex()

A convenience method that returns the first selected index.

getSelectedIndices()

Return an array of all of the selected indices in increasing order.

getSelectedValue()

A convenience method that returns the first selected value or null, if the selection is empty.

getSelectedValues()

Return an array of the values for the selected cells.

getSelectionModel()

getUI()

getUIClassID()

getValueIsAdjusting(boolean)

getVisibleRowCount()

Return the value of the visibleRowCount property.

indexToLocation(int)

Returns the origin of the specified item in JList coordinates, null if index isn't valid.

isOpaque()

JList components are always opaque.

isSelectedIndex(int)

Returns true if the specified index is selected.

isSelectionEmpty()

Returns true if nothing is selected This is a convenience method that just delegates to the selectionModel.

locationToIndex(Point)

Convert a point in JList coordinates to the index of the cell at that location.

removeListSelectionListener(ListSelectionListener)

Remove a listener from the list that's notified each time a change to the selection occurs.

removeSelectionInterval(int, int)

Set the selection to be the set difference of the specified interval and the current selection.

setCellRenderer(ListCellRenderer)

Sets the delegate that's used to paint each cell in the list.

setFixedCellHeight(int)

If this value is greater than zero it defines the width of every cell in the list.

setFixedCellWidth(int)

If this value is greater than zero it defines the width of every cell in the list.

setListData(Object[])

A convenience method that constructs a ListModel from the object array and then applies setModel to it.

setListData(Vector)

A convenience method that constructs a ListModel from the Vector and then applies setModel to it.

setModel(ListModel)

Sets the model that represents the contents or "value" of the list and clears the lists selection after notifying PropertyChangeListeners.

setPrototypeCellValue(Object)

If this value is non-null it's used to compute fixedCellWidth and fixedCellHeight by configuring the cellRenderer at index equals zero for the specified value and then computing the renderer components preferred size.

setSelectedIndex(int)

Select a single cell.

setSelectedIndices(int[])

Select a set of cells.

setSelectedValue(Object, boolean)

setSelectionInterval(int, int)

Select the specified interval.

setSelectionModel(ListSelectionModel)

Set the selectionModel for the list to a non null ListSelectionModel implementation.

setUI(ListUI)

Set the ListUI look and feel implementation delegate.

setValueIsAdjusting(boolean)

setVisibleRowCount(int)

Set the preferred number of rows in the list that are visible within the nearest JViewport ancestor, if any.

updateUI()

Set the UI property with the "ListUI" from the current default UIFactory.

 public JList(ListModel dataModel)

Construct a JList that displays the elements in the specified, non-null model. All JList constructors delegate to this one.

 public JList(Object listData[])

Construct a JList that displays the elements in the specified array. This constructor just delegates to the ListModel constructor.

 public JList(Vector listData)

Construct a JList that displays the elements in the specified Vector. This constructor just delegates to the ListModel constructor.

 public JList()

Constructs a JList with an empty model.

 public ListUI getUI()

Returns:

the value of the UI property.

See Also:

setUI

 public void setUI(ListUI ui)

Set the ListUI look and feel implementation delegate.

See Also:

getUI

 public void updateUI()

Set the UI property with the "ListUI" from the current default UIFactory. This method is called by the JList constructor and to update the Lists look and feel at runtime.

Overrides:

updateUI in class JComponent

See Also:

getUI

 public String getUIClassID()

Returns:

"ListUI"

Overrides:

getUIClassID in class JComponent

See Also:

getUIClassID, getUI

 public boolean isOpaque()

JList components are always opaque.

Returns:

true

Overrides:

isOpaque in class JComponent

 public Object getPrototypeCellValue()

Returns:

the value of the prototypeCellValue property

See Also:

setPrototypeCellValue

 public void setPrototypeCellValue(Object prototypeCellValue)

If this value is non-null it's used to compute fixedCellWidth and fixedCellHeight by configuring the cellRenderer at index equals zero for the specified value and then computing the renderer components preferred size. This property is useful when the list is too long to allow JList to just compute the width/height of each cell and there's single cell value that's known to occupy as much space as any of the others.

The default value of this property is null.

This is a JavaBeans bound property. Note that we do set the fixedCellWidth and fixedCellHeight properties here but only a prototypeCellValue PropertyChangeEvent is fired.

Parameters:

the - value to base fixedCellWidth and fixedCellHeight on.

See Also:

getPrototypeCellValue, setFixedCellWidth, setFixedCellHeight, addPropertyChangeEvent

 public int getFixedCellWidth()

Returns:

the value of the fixedCellWidth property.

See Also:

setFixedCellWidth

 public void setFixedCellWidth(int width)

If this value is greater than zero it defines the width of every cell in the list. Otherwise cell widths are computed by applying getPreferredSize() to the cellRenderer component for each list element.

The default value of this property is -1.

This is a JavaBeans bound property.

Parameters:

the - width for all cells in this list

See Also:

getPrototypeCellValue, setFixedCellWidth, addPropertyChangeEvent

 public int getFixedCellHeight()

Returns:

the value of the fixedCellHeight property.

See Also:

setFixedCellHeight

 public void setFixedCellHeight(int height)

If this value is greater than zero it defines the width of every cell in the list. Otherwise cell widths are computed by applying getPreferredSize() to the cellRenderer component for each list element.

The default value of this property is -1.

This is a JavaBeans bound property.

Parameters:

the - width for all cells in this list

See Also:

getPrototypeCellValue, setFixedCellWidth, addPropertyChangeEvent

 public ListCellRenderer getCellRenderer()

Returns:

the value of the cellRenderer property.

See Also:

setCellRenderer

 public void setCellRenderer(ListCellRenderer cellRenderer)

Sets the delegate that's used to paint each cell in the list. If prototypeCellValue was set then the fixedCellWidth and fixedCellHeight properties are set as well. Only one PropertyChangeEvent is generated however - for the "cellRenderer" property.

The default value of this property is provided by ListUI delegate, i.e. by the look and feel implementation.

This is a JavaBeans bound property.

See Also:

createDefaultCellRenderer, getCellRenderer

 public int getVisibleRowCount()

Return the value of the visibleRowCount property.

See Also:

setVisibleRowCount

 public void setVisibleRowCount(int visibleRowCount)

Set the preferred number of rows in the list that are visible within the nearest JViewport ancestor, if any. The value of this property only affects the value of the JLists preferredScrollableViewportSize.

The default value of this property is 8.

This is a JavaBeans bound property.

See Also:

getVisibleRowCount, getVisibleRect

 public int getFirstVisibleIndex()

Return the index of the cell in the upper left corner of the JList or -1 if nothing is visible or the list is empty. Note that this cell may only be partially visible.

Returns:

The index of the first visible cell.

See Also:

getLastVisibleIndex, getVisibleRect

 public int getLastVisibleIndex()

Return the index of the cell in the lower right corner of the JList or -1 if nothing is visible or the list is empty. Note that this cell may only be partially visible.

Returns:

The index of the last visible cell.

See Also:

getLastVisibleIndex, getVisibleRect

 public void ensureIndexIsVisible(int index)

If this JList is being displayed withing a JViewport and the specified cell isn't completely visible, scroll the viewport.

Parameters:

The - index of the cell to make visible

See Also:

scrollRectToVisible, getVisibleRect

 public int locationToIndex(Point location)

Convert a point in JList coordinates to the index of the cell at that location. Returns -1 if there's no cell the specified location.

Parameters:

location - The JList relative coordinates of the cell

Returns:

The index of the cell at location, or -1.

 public Point indexToLocation(int index)

Returns the origin of the specified item in JList coordinates, null if index isn't valid.

Parameters:

index - The index of the JList cell.

Returns:

The origin of the index'th cell.

 public Rectangle getCellBounds(int index1,
                                int index2)

Returns the bounds of the specified item in JList coordinates, null if index isn't valid.

Parameters:

index - The index of the JList cell.

Returns:

The bounds of the index'th cell.

 public ListModel getModel()

Returns:

the value of the model property.

See Also:

setModel

 public void setModel(ListModel model)

Sets the model that represents the contents or "value" of the list and clears the lists selection after notifying PropertyChangeListeners.

This is a JavaBeans bound property.

See Also:

getModel

 public void setListData(Object listData[])

A convenience method that constructs a ListModel from the object array and then applies setModel to it.

See Also:

setModel

 public void setListData(Vector listData)

A convenience method that constructs a ListModel from the Vector and then applies setModel to it.

See Also:

setModel

 protected ListSelectionModel createSelectionModel()

Returns an instance of DefaultListSelectionModel. This method is used by the constructor to initialize the selectionModel property.

Returns:

The ListSelectionModel used by this JList.

See Also:

setSelectionModel,

 public ListSelectionModel getSelectionModel()

Returns:

the value of the selectionModel property

See Also:

setSelectionModel

 protected void fireSelectionValueChanged(int firstIndex,
                                          int lastIndex,
                                          boolean isAdjusting)

This method notifies JList ListSelectionListeners that the selection model has changed. It's used to forward ListSelectionEvents from the selectionModel to the ListSelectionListeners added directly to the JList.

See Also:

addListSelectionModel, removeListSelectionModel, EventListenerList

 public void addListSelectionListener(ListSelectionListener listener)

Add a listener to the list that's notified each time a change to the selection occurs. Listeners added directly to the JList will have their ListSelectionEvent.getSource() == this JList (instead of the ListSelectionModel).

Parameters:

listener - The ListSelectionListener to add.

See Also:

getSelectionModel

 public void removeListSelectionListener(ListSelectionListener listener)

Remove a listener from the list that's notified each time a change to the selection occurs.

Parameters:

listener - The ListSelectionListener to remove.

See Also:

addListSelectionListener, getSelectionModel

 public void setSelectionModel(ListSelectionModel selectionModel)

Set the selectionModel for the list to a non null ListSelectionModel implementation.

This is a JavaBeans bound property.

See Also:

getSelectionModel

 public int getAnchorSelectionIndex()

Returns the first index argument from the most recent addSelectionInterval or setSelectionInterval call. This is a convenience method that just delegates to the selectionModel.

Returns:

The index that most recently anchored an interval selection.

See Also:

getAnchorSelectionIndex, addSelectionInterval, setSelectionInterval, addListSelectionListener

 public int getLeadSelectionIndex()

Returns the second index argument from the most recent addSelectionInterval or setSelectionInterval call. This is a convenience method that just delegates to the selectionModel.

Returns:

The index that most recently ended a interval selection.

See Also:

getLeadSelectionIndex, addSelectionInterval, setSelectionInterval, addListSelectionListener

 public int getMinSelectionIndex()

Returns the smallest selected cell index. This is a convenience method that just delegates to the selectionModel.

Returns:

The smallest selected cell index.

See Also:

getMinSelectionIndex, addListSelectionListener

 public int getMaxSelectionIndex()

Returns the largest selected cell index. This is a convenience method that just delegates to the selectionModel.

Returns:

The largest selected cell index.

See Also:

getMaxSelectionIndex, addListSelectionListener

 public boolean isSelectedIndex(int index)

Returns true if the specified index is selected. This is a convenience method that just delegates to the selectionModel.

Returns:

True if the specified index is selected.

See Also:

isSelectedIndex, setSelectedIndex, addListSelectionListener

 public boolean isSelectionEmpty()

Returns true if nothing is selected This is a convenience method that just delegates to the selectionModel.

Returns:

True if nothing is selected

See Also:

isSelectionEmpty, clearSelection, addListSelectionListener

 public void clearSelection()

Clears the selection - after calling this method isSelectionEmpty() will return true. This is a convenience method that just delegates to the selectionModel.

See Also:

clearSelection, isSelectionEmpty, addListSelectionListener

 public void setSelectionInterval(int anchor,
                                  int lead)

Select the specified interval. Both the anchor and lead indices are included. It's not neccessary for anchor to be less than lead. This is a convenience method that just delegates to the selectionModel.

Parameters:

anchor - The first index to select

lead - The last index to select

See Also:

setSelectionInterval, addSelectionInterval, removeSelectionInterval, addListSelectionListener

 public void addSelectionInterval(int anchor,
                                  int lead)

Set the selection to be the union of the specified interval with current selection. Both the anchor and lead indices are included. It's not neccessary for anchor to be less than lead. This is a convenience method that just delegates to the selectionModel.

Parameters:

anchor - The first index to add to the selection

lead - The last index to add to the selection

See Also:

addSelectionInterval, setSelectionInterval, removeSelectionInterval, addListSelectionListener

 public void removeSelectionInterval(int index0,
                                     int index1)

Set the selection to be the set difference of the specified interval and the current selection. Both the anchor and lead indices are removed. It's not neccessary for anchor to be less than lead. This is a convenience method that just delegates to the selectionModel.

Parameters:

anchor - The first index to remove from the selection

lead - The last index to remove from the selection

See Also:

removeSelectionInterval, setSelectionInterval, addSelectionInterval, addListSelectionListener

 public void setValueIsAdjusting(boolean b)

 public boolean getValueIsAdjusting(boolean b)

 public int[] getSelectedIndices()

Return an array of all of the selected indices in increasing order.

Returns:

All of the selected indices, in increasing order.

See Also:

removeSelectionInterval, addListSelectionListener

 public void setSelectedIndex(int index)

Select a single cell.

Parameters:

index - The index of the one cell to select

See Also:

setSelectionInterval, isSelectedIndex, addListSelectionListener

 public void setSelectedIndices(int indices[])

Select a set of cells.

Parameters:

indices - The indices of the cells to select

See Also:

addSelectionInterval, isSelectedIndex, addListSelectionListener

 public Object[] getSelectedValues()

Return an array of the values for the selected cells. The returned values are sorted in increasing index order.

Returns:

the selected values

See Also:

isSelectedIndex, getModel, addListSelectionListener

 public int getSelectedIndex()

A convenience method that returns the first selected index.

Returns:

The first selected index.

See Also:

getMinSelectionIndex, addListSelectionListener

 public Object getSelectedValue()

A convenience method that returns the first selected value or null, if the selection is empty.

Returns:

The first selected value.

See Also:

getMinSelectionIndex, getModel, addListSelectionListener

 public void setSelectedValue(Object anObject,
                              boolean shouldScroll)

 public AccessibleStateSet getAccessibleStateSet()

Get the state set of this object.

Returns:

an instance of AccessibleState containing the current state of the object

Overrides:

getAccessibleStateSet in class JComponent

See Also:

AccessibleState

 public AccessibleRole getAccessibleRole()

Get the role of this object.

Returns:

an instance of AccessibleRole describing the role of the object

Overrides:

getAccessibleRole in class JComponent

See Also:

AccessibleRole

 public Accessible getAccessibleAt(Point p)

Returns the Accessible child contained at the local coordinate Point, if one exists.

Returns:

the Accessible at the specified location, if it exists

Overrides:

getAccessibleAt in class JComponent

 public int getAccessibleChildrenCount()

Returns the number of accessible children in the object. If all of the children of this object implement Accessible, than this method should return the number of children of this object.

Returns:

the number of accessible children in the object.

Overrides:

getAccessibleChildrenCount in class JComponent

 public Accessible getAccessibleChild(int i)

Return the nth Accessible child of the object.

Parameters:

i - zero-based index of child

Returns:

the nth Accessible child of the object

Overrides:

getAccessibleChild in class JComponent

 public Dimension getPreferredScrollableViewportSize()

Compute the size of the viewport needed to display visibleRowCount rows. This is trivial if fixedCellWidth and fixedCellHeight were specified. Note that they can specified implicitly with the prototypeCellValue property. If fixedCellWidth wasn't specified, it's computed by finding the widest list element. If fixedCellHeight wasn't specified then we resort to heuristics:

• If the model isn't empty we just multiply the height of the first row by visibleRowCount.
• If the model is empty, i.e. JList.getModel().getSize() == 0, then we just allocate 16 pixels per visible row, and 100 pixels for the width (unless fixedCellWidth was set), and hope for the best.

See Also:

getPreferredScrollableViewportSize, setPrototypeCellValue

 public int getScrollableUnitIncrement(Rectangle visibleRect,
                                       int orientation,
                                       int direction)

If we're scrolling downwards (direction is greater than 0), and the first row is completely visible with respect to visibleRect, then return its height. If we're scrolling downwards and the first row is only partially visible, return the height of the visible part of the first row. Similarly if we're scrolling upwards we return the height of the row above the first row, unless the first row is partially visible.

Returns:

The distance to scroll to expose the next or previous row.

See Also:

getScrollableUnitIncrement

 public int getScrollableBlockIncrement(Rectangle visibleRect,
                                        int orientation,
                                        int direction)

Returns:

The visibleRect.height or visibleRect.width per the orientation.

See Also:

getScrollableUnitIncrement

 public boolean getScrollableTracksViewportWidth()

If this JList is displayed in a JViewport, don't change its width when the viewports width changes. This allows horizontal scrolling if the JViewport is itself embedded in a JScrollPane.

Returns:

False - don't track the viewports width.

See Also:

getScrollableTracksViewportWidth

 public boolean getScrollableTracksViewportHeight()

If this JList is displayed in a JViewport, don't change its height when the viewports height changes. This allows vertical scrolling if the JViewport is itself embedded in a JScrollPane.

Returns:

False - don't track the viewports width.

See Also:

getScrollableTracksViewportWidth

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