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Java™ Platform Standard Ed. 6 |
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java.lang.Object java.awt.Component java.awt.Container javax.swing.JComponent javax.swing.JList
public class JList
A component that displays a list of objects and allows the user to select
one or more items. A separate model, ListModel
, maintains the
contents of the list.
It's easy to display an array or Vector of objects, using the JList
constructor that automatically builds a read-only ListModel
instance
for you:
// Create a JList that displays strings from an array String[] data = {"one", "two", "three", "four"}; JList myList = new JList(data); // Create a JList that displays the superclasses of JList.class, by // creating it with a Vector populated with this data Vector superClasses = new Vector(); Class rootClass = javax.swing.JList.class; for(Class cls = rootClass; cls != null; cls = cls.getSuperclass()) { superClasses.addElement(cls); } JList myList = new JList(superClasses); // The automatically created model is stored in JList's "model" // property, which you can retrieve ListModel model = myList.getModel(); for(int i = 0; i < model.getSize(); i++) { System.out.println(model.getElementAt(i)); }
A ListModel
can be supplied directly to a JList
by way of a
constructor or the setModel
method. The contents need not be static -
the number of items, and the values of items can change over time. A correct
ListModel
implementation notifies the set of
javax.swing.event.ListDataListener
s that have been added to it, each
time a change occurs. These changes are characterized by a
javax.swing.event.ListDataEvent
, which identifies the range of list
indices that have been modified, added, or removed. JList
's
ListUI
is responsible for keeping the visual representation up to
date with changes, by listening to the model.
Simple, dynamic-content, JList
applications can use the
DefaultListModel
class to maintain list elements. This class
implements the ListModel
interface and also provides a
java.util.Vector
-like API. Applications that need a more
custom ListModel
implementation may instead wish to subclass
AbstractListModel
, which provides basic support for managing and
notifying listeners. For example, a read-only implementation of
AbstractListModel
:
// 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; } };
The selection state of a JList
is managed by another separate
model, an instance of ListSelectionModel
. JList
is
initialized with a selection model on construction, and also contains
methods to query or set this selection model. Additionally, JList
provides convenient methods for easily managing the selection. These methods,
such as setSelectedIndex
and getSelectedValue
, are cover
methods that take care of the details of interacting with the selection
model. By default, JList
's selection model is configured to allow any
combination of items to be selected at a time; selection mode
MULTIPLE_INTERVAL_SELECTION
. The selection mode can be changed
on the selection model directly, or via JList
's cover method.
Responsibility for updating the selection model in response to user gestures
lies with the list's ListUI
.
A correct ListSelectionModel
implementation notifies the set of
javax.swing.event.ListSelectionListener
s that have been added to it
each time a change to the selection occurs. These changes are characterized
by a javax.swing.event.ListSelectionEvent
, which identifies the range
of the selection change.
The preferred way to listen for changes in list selection is to add
ListSelectionListener
s directly to the JList
. JList
then takes care of listening to the the selection model and notifying your
listeners of change.
Responsibility for listening to selection changes in order to keep the list's
visual representation up to date lies with the list's ListUI
.
Painting of cells in a
Another job for the cell renderer is in helping to determine sizing
information for the list. By default, the list's
Warning: Swing is not thread safe. For more
information see Swing's Threading
Policy.
Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing. As of 1.4, support for long term storage
of all JavaBeansTM
has been added to the
See How to Use Lists
in The Java Tutorial
for further documentation.
Also see the article Advanced JList Programming
in The Swing Connection.
JList
is handled by a delegate called a
cell renderer, installed on the list as the cellRenderer
property.
The renderer provides a java.awt.Component
that is used
like a "rubber stamp" to paint the cells. Each time a cell needs to be
painted, the list's ListUI
asks the cell renderer for the component,
moves it into place, and has it paint the contents of the cell by way of its
paint
method. A default cell renderer, which uses a JLabel
component to render, is installed by the lists's ListUI
. You can
substitute your own renderer using code like this:
// 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, // the list
Object value, // value to display
int index, // cell index
boolean isSelected, // is the cell selected
boolean cellHasFocus) // does the cell have focus
{
String s = value.toString();
setText(s);
setIcon((s.length() > 10) ? longIcon : shortIcon);
if (isSelected) {
setBackground(list.getSelectionBackground());
setForeground(list.getSelectionForeground());
} else {
setBackground(list.getBackground());
setForeground(list.getForeground());
}
setEnabled(list.isEnabled());
setFont(list.getFont());
setOpaque(true);
return this;
}
}
myList.setCellRenderer(new MyCellRenderer());
ListUI
determines
the size of cells by asking the cell renderer for its preferred
size for each list item. This can be expensive for large lists of items.
To avoid these calculations, you can set a fixedCellWidth
and
fixedCellHeight
on the list, or have these values calculated
automatically based on a single prototype value:
JList bigDataList = new JList(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
doesn't implement scrolling directly. To create a list that
scrolls, make it the viewport view of a JScrollPane
. For example:
JScrollPane scrollPane = new JScrollPane(myList);
// Or in two steps:
JScrollPane scrollPane = new JScrollPane();
scrollPane.getViewport().setView(myList);
JList
doesn't provide any special handling of double or triple
(or N) mouse clicks, but it's easy to add a MouseListener
if you
wish to take action on these events. Use the locationToIndex
method to determine what cell was clicked. For example:
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);
java.beans
package.
Please see XMLEncoder
.
ListModel
,
AbstractListModel
,
DefaultListModel
,
ListSelectionModel
,
DefaultListSelectionModel
,
ListCellRenderer
,
DefaultListCellRenderer
Nested Class Summary | |
---|---|
protected class |
JList.AccessibleJList
This class implements accessibility support for the JList class. |
static class |
JList.DropLocation
A subclass of TransferHandler.DropLocation representing
a drop location for a JList . |
Nested classes/interfaces inherited from class javax.swing.JComponent |
---|
JComponent.AccessibleJComponent |
Nested classes/interfaces inherited from class java.awt.Container |
---|
Container.AccessibleAWTContainer |
Nested classes/interfaces inherited from class java.awt.Component |
---|
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy |
Field Summary | |
---|---|
static int |
HORIZONTAL_WRAP
Indicates a "newspaper style" layout with cells flowing horizontally then vertically. |
static int |
VERTICAL
Indicates a vertical layout of cells, in a single column; the default layout. |
static int |
VERTICAL_WRAP
Indicates a "newspaper style" layout with cells flowing vertically then horizontally. |
Fields inherited from class javax.swing.JComponent |
---|
accessibleContext, listenerList, TOOL_TIP_TEXT_KEY, ui, UNDEFINED_CONDITION, WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, WHEN_FOCUSED, WHEN_IN_FOCUSED_WINDOW |
Fields inherited from class java.awt.Component |
---|
BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT |
Fields inherited from interface java.awt.image.ImageObserver |
---|
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH |
Constructor Summary | |
---|---|
JList()
Constructs a JList with an empty, read-only, model. |
|
JList(ListModel dataModel)
Constructs a JList that displays elements from the specified,
non-null , model. |
|
JList(Object[] listData)
Constructs a JList that displays the elements in
the specified array. |
|
JList(Vector<?> listData)
Constructs a JList that displays the elements in
the specified Vector . |
Method Summary | |
---|---|
void |
addListSelectionListener(ListSelectionListener listener)
Adds a listener to the list, to be notified each time a change to the selection occurs; the preferred way of listening for selection state changes. |
void |
addSelectionInterval(int anchor,
int lead)
Sets the selection to be the union of the specified interval with current selection. |
void |
clearSelection()
Clears the selection; after calling this method, isSelectionEmpty
will return true . |
protected ListSelectionModel |
createSelectionModel()
Returns an instance of DefaultListSelectionModel ; called
during construction to initialize the list's selection model
property. |
void |
ensureIndexIsVisible(int index)
Scrolls the list within an enclosing viewport to make the specified cell completely visible. |
protected void |
fireSelectionValueChanged(int firstIndex,
int lastIndex,
boolean isAdjusting)
Notifies ListSelectionListener s added directly to the list
of selection changes made to the selection model. |
AccessibleContext |
getAccessibleContext()
Gets the AccessibleContext associated with this JList . |
int |
getAnchorSelectionIndex()
Returns the anchor selection index. |
Rectangle |
getCellBounds(int index0,
int index1)
Returns the bounding rectangle, in the list's coordinate system, for the range of cells specified by the two indices. |
ListCellRenderer |
getCellRenderer()
Returns the object responsible for painting list items. |
boolean |
getDragEnabled()
Returns whether or not automatic drag handling is enabled. |
JList.DropLocation |
getDropLocation()
Returns the location that this component should visually indicate as the drop location during a DnD operation over the component, or null if no location is to currently be shown. |
DropMode |
getDropMode()
Returns the drop mode for this component. |
int |
getFirstVisibleIndex()
Returns the smallest list index that is currently visible. |
int |
getFixedCellHeight()
Returns the value of the fixedCellHeight property. |
int |
getFixedCellWidth()
Returns the value of the fixedCellWidth property. |
int |
getLastVisibleIndex()
Returns the largest list index that is currently visible. |
int |
getLayoutOrientation()
Returns the layout orientation property for the list: VERTICAL
if the layout is a single column of cells, VERTICAL_WRAP if the
layout is "newspaper style" with the content flowing vertically then
horizontally, or HORIZONTAL_WRAP if the layout is "newspaper
style" with the content flowing horizontally then vertically. |
int |
getLeadSelectionIndex()
Returns the lead selection index. |
ListSelectionListener[] |
getListSelectionListeners()
Returns an array of all the ListSelectionListener s added
to this JList by way of addListSelectionListener . |
int |
getMaxSelectionIndex()
Returns the largest selected cell index, or -1 if the selection
is empty. |
int |
getMinSelectionIndex()
Returns the smallest selected cell index, or -1 if the selection
is empty. |
ListModel |
getModel()
Returns the data model that holds the list of items displayed by the JList component. |
int |
getNextMatch(String prefix,
int startIndex,
Position.Bias bias)
Returns the next list element whose toString value
starts with the given prefix. |
Dimension |
getPreferredScrollableViewportSize()
Computes the size of viewport needed to display visibleRowCount
rows. |
Object |
getPrototypeCellValue()
Returns the "prototypical" cell value -- a value used to calculate a fixed width and height for cells. |
int |
getScrollableBlockIncrement(Rectangle visibleRect,
int orientation,
int direction)
Returns the distance to scroll to expose the next or previous block. |
boolean |
getScrollableTracksViewportHeight()
Returns true if this JList is displayed in a
JViewport and the viewport is taller than the list's
preferred height, or if the layout orientation is VERTICAL_WRAP
and visibleRowCount <= 0 ; otherwise returns false . |
boolean |
getScrollableTracksViewportWidth()
Returns true if this JList is displayed in a
JViewport and the viewport is wider than the list's
preferred width, or if the layout orientation is HORIZONTAL_WRAP
and visibleRowCount <= 0 ; otherwise returns false . |
int |
getScrollableUnitIncrement(Rectangle visibleRect,
int orientation,
int direction)
Returns the distance to scroll to expose the next or previous row (for vertical scrolling) or column (for horizontal scrolling). |
int |
getSelectedIndex()
Returns the smallest selected cell index; the selection when only a single item is selected in the list. |
int[] |
getSelectedIndices()
Returns an array of all of the selected indices, in increasing order. |
Object |
getSelectedValue()
Returns the value for the smallest selected cell index; the selected value when only a single item is selected in the list. |
Object[] |
getSelectedValues()
Returns an array of all the selected values, in increasing order based on their indices in the list. |
Color |
getSelectionBackground()
Returns the color used to draw the background of selected items. |
Color |
getSelectionForeground()
Returns the color used to draw the foreground of selected items. |
int |
getSelectionMode()
Returns the current selection mode for the list. |
ListSelectionModel |
getSelectionModel()
Returns the current selection model. |
String |
getToolTipText(MouseEvent event)
Returns the tooltip text to be used for the given event. |
ListUI |
getUI()
Returns the ListUI , the look and feel object that
renders this component. |
String |
getUIClassID()
Returns "ListUI" , the UIDefaults key used to look
up the name of the javax.swing.plaf.ListUI class that defines
the look and feel for this component. |
boolean |
getValueIsAdjusting()
Returns the value of the selection model's isAdjusting property. |
int |
getVisibleRowCount()
Returns the value of the visibleRowCount property. |
Point |
indexToLocation(int index)
Returns the origin of the specified item in the list's coordinate system. |
boolean |
isSelectedIndex(int index)
Returns true if the specified index is selected,
else false . |
boolean |
isSelectionEmpty()
Returns true if nothing is selected, else false . |
int |
locationToIndex(Point location)
Returns the cell index closest to the given location in the list's coordinate system. |
protected String |
paramString()
Returns a String representation of this JList . |
void |
removeListSelectionListener(ListSelectionListener listener)
Removes a selection listener from the list. |
void |
removeSelectionInterval(int index0,
int index1)
Sets the selection to be the set difference of the specified interval and the current selection. |
void |
setCellRenderer(ListCellRenderer cellRenderer)
Sets the delegate that is used to paint each cell in the list. |
void |
setDragEnabled(boolean b)
Turns on or off automatic drag handling. |
void |
setDropMode(DropMode dropMode)
Sets the drop mode for this component. |
void |
setFixedCellHeight(int height)
Sets a fixed value to be used for the height of every cell in the list. |
void |
setFixedCellWidth(int width)
Sets a fixed value to be used for the width of every cell in the list. |
void |
setLayoutOrientation(int layoutOrientation)
Defines the way list cells are layed out. |
void |
setListData(Object[] listData)
Constructs a read-only ListModel from an array of objects,
and calls setModel with this model. |
void |
setListData(Vector<?> listData)
Constructs a read-only ListModel from a Vector
and calls setModel with this model. |
void |
setModel(ListModel model)
Sets the model that represents the contents or "value" of the list, notifies property change listeners, and then clears the list's selection. |
void |
setPrototypeCellValue(Object prototypeCellValue)
Sets the prototypeCellValue property, and then (if the new value
is non-null ), computes the fixedCellWidth and
fixedCellHeight properties by requesting the cell renderer
component for the given value (and index 0) from the cell renderer, and
using that component's preferred size. |
void |
setSelectedIndex(int index)
Selects a single cell. |
void |
setSelectedIndices(int[] indices)
Changes the selection to be the set of indices specified by the given array. |
void |
setSelectedValue(Object anObject,
boolean shouldScroll)
Selects the specified object from the list. |
void |
setSelectionBackground(Color selectionBackground)
Sets the color used to draw the background of selected items, which cell renderers can use fill selected cells. |
void |
setSelectionForeground(Color selectionForeground)
Sets the color used to draw the foreground of selected items, which cell renderers can use to render text and graphics. |
void |
setSelectionInterval(int anchor,
int lead)
Selects the specified interval. |
void |
setSelectionMode(int selectionMode)
Sets the selection mode for the list. |
void |
setSelectionModel(ListSelectionModel selectionModel)
Sets the selectionModel for the list to a
non-null ListSelectionModel
implementation. |
void |
setUI(ListUI ui)
Sets the ListUI , the look and feel object that
renders this component. |
void |
setValueIsAdjusting(boolean b)
Sets the selection model's valueIsAdjusting property. |
void |
setVisibleRowCount(int visibleRowCount)
Sets the visibleRowCount property, which has different meanings
depending on the layout orientation: For a VERTICAL layout
orientation, this sets the preferred number of rows to display without
requiring scrolling; for other orientations, it affects the wrapping of
cells. |
void |
updateUI()
Resets the ListUI property by setting it to the value provided
by the current look and feel. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Field Detail |
---|
public static final int VERTICAL
setLayoutOrientation(int)
,
Constant Field Valuespublic static final int VERTICAL_WRAP
setLayoutOrientation(int)
,
Constant Field Valuespublic static final int HORIZONTAL_WRAP
setLayoutOrientation(int)
,
Constant Field ValuesConstructor Detail |
---|
public JList(ListModel dataModel)
JList
that displays elements from the specified,
non-null
, model. All JList
constructors delegate to
this one.
This constructor registers the list with the ToolTipManager
,
allowing for tooltips to be provided by the cell renderers.
dataModel
- the model for the list
IllegalArgumentException
- if the model is null
public JList(Object[] listData)
JList
that displays the elements in
the specified array. This constructor creates a read-only model
for the given array, and then delegates to the constructor that
takes a ListModel
.
Attempts to pass a null
value to this method results in
undefined behavior and, most likely, exceptions. The created model
references the given array directly. Attempts to modify the array
after constructing the list results in undefined behavior.
listData
- the array of Objects to be loaded into the data model,
non-null
public JList(Vector<?> listData)
JList
that displays the elements in
the specified Vector
. This constructor creates a read-only
model for the given Vector
, and then delegates to the constructor
that takes a ListModel
.
Attempts to pass a null
value to this method results in
undefined behavior and, most likely, exceptions. The created model
references the given Vector
directly. Attempts to modify the
Vector
after constructing the list results in undefined behavior.
listData
- the Vector
to be loaded into the
data model, non-null
public JList()
JList
with an empty, read-only, model.
Method Detail |
---|
public ListUI getUI()
ListUI
, the look and feel object that
renders this component.
ListUI
object that renders this componentpublic void setUI(ListUI ui)
ListUI
, the look and feel object that
renders this component.
ui
- the ListUI
objectUIDefaults.getUI(javax.swing.JComponent)
public void updateUI()
ListUI
property by setting it to the value provided
by the current look and feel. If the current cell renderer was installed
by the developer (rather than the look and feel itself), this also causes
the cell renderer and its children to be updated, by calling
SwingUtilities.updateComponentTreeUI
on it.
updateUI
in class JComponent
public String getUIClassID()
"ListUI"
, the UIDefaults
key used to look
up the name of the javax.swing.plaf.ListUI
class that defines
the look and feel for this component.
getUIClassID
in class JComponent
JComponent.getUIClassID()
,
UIDefaults.getUI(javax.swing.JComponent)
public Object getPrototypeCellValue()
null
if there
is no such value.
prototypeCellValue
propertysetPrototypeCellValue(java.lang.Object)
public void setPrototypeCellValue(Object prototypeCellValue)
prototypeCellValue
property, and then (if the new value
is non-null
), computes the fixedCellWidth
and
fixedCellHeight
properties by requesting the cell renderer
component for the given value (and index 0) from the cell renderer, and
using that component's preferred size.
This method is useful when the list is too long to allow the
ListUI
to compute the width/height of each cell, and there is a
single cell value that is known to occupy as much space as any of the
others, a so-called prototype.
While all three of the prototypeCellValue
,
fixedCellHeight
, and fixedCellWidth
properties may be
modified by this method, PropertyChangeEvent
notifications are
only sent when the prototypeCellValue
property changes.
To see an example which sets this property, see the class description above.
The default value of this property is null
.
This is a JavaBeans bound property.
prototypeCellValue
- the value on which to base
fixedCellWidth
and
fixedCellHeight
getPrototypeCellValue()
,
setFixedCellWidth(int)
,
setFixedCellHeight(int)
,
Container.addPropertyChangeListener(java.beans.PropertyChangeListener)
public int getFixedCellWidth()
fixedCellWidth
property.
setFixedCellWidth(int)
public void setFixedCellWidth(int width)
width
is -1, cell widths are computed in the ListUI
by applying getPreferredSize
to the cell renderer component
for each list element.
The default value of this property is -1
.
This is a JavaBeans bound property.
width
- the width to be used for all cells in the listsetPrototypeCellValue(java.lang.Object)
,
setFixedCellWidth(int)
,
Container.addPropertyChangeListener(java.beans.PropertyChangeListener)
public int getFixedCellHeight()
fixedCellHeight
property.
setFixedCellHeight(int)
public void setFixedCellHeight(int height)
height
is -1, cell heights are computed in the ListUI
by applying getPreferredSize
to the cell renderer component
for each list element.
The default value of this property is -1
.
This is a JavaBeans bound property.
height
- the height to be used for for all cells in the listsetPrototypeCellValue(java.lang.Object)
,
setFixedCellWidth(int)
,
Container.addPropertyChangeListener(java.beans.PropertyChangeListener)
public ListCellRenderer getCellRenderer()
cellRenderer
propertysetCellRenderer(javax.swing.ListCellRenderer)
public void setCellRenderer(ListCellRenderer cellRenderer)
If the prototypeCellValue
property is non-null
,
setting the cell renderer also causes the fixedCellWidth
and
fixedCellHeight
properties to be re-calculated. Only one
PropertyChangeEvent
is generated however -
for the cellRenderer
property.
The default value of this property is provided by the ListUI
delegate, i.e. by the look and feel implementation.
This is a JavaBeans bound property.
cellRenderer
- the ListCellRenderer
that paints list cellsgetCellRenderer()
public Color getSelectionForeground()
DefaultListCellRenderer
uses this color to draw the foreground
of items in the selected state, as do the renderers installed by most
ListUI
implementations.
setSelectionForeground(java.awt.Color)
,
DefaultListCellRenderer
public void setSelectionForeground(Color selectionForeground)
DefaultListCellRenderer
uses this color to draw the foreground
of items in the selected state, as do the renderers installed by most
ListUI
implementations.
The default value of this property is defined by the look and feel implementation.
This is a JavaBeans bound property.
selectionForeground
- the Color
to use in the foreground
for selected list itemsgetSelectionForeground()
,
setSelectionBackground(java.awt.Color)
,
JComponent.setForeground(java.awt.Color)
,
JComponent.setBackground(java.awt.Color)
,
JComponent.setFont(java.awt.Font)
,
DefaultListCellRenderer
public Color getSelectionBackground()
DefaultListCellRenderer
uses this color to draw the background
of items in the selected state, as do the renderers installed by most
ListUI
implementations.
setSelectionBackground(java.awt.Color)
,
DefaultListCellRenderer
public void setSelectionBackground(Color selectionBackground)
DefaultListCellRenderer
uses this color to fill the background
of items in the selected state, as do the renderers installed by most
ListUI
implementations.
The default value of this property is defined by the look and feel implementation.
This is a JavaBeans bound property.
selectionBackground
- the Color
to use for the
background of selected cellsgetSelectionBackground()
,
setSelectionForeground(java.awt.Color)
,
JComponent.setForeground(java.awt.Color)
,
JComponent.setBackground(java.awt.Color)
,
JComponent.setFont(java.awt.Font)
,
DefaultListCellRenderer
public int getVisibleRowCount()
visibleRowCount
property. See the
documentation for setVisibleRowCount(int)
for details on how to
interpret this value.
visibleRowCount
property.setVisibleRowCount(int)
public void setVisibleRowCount(int visibleRowCount)
visibleRowCount
property, which has different meanings
depending on the layout orientation: For a VERTICAL
layout
orientation, this sets the preferred number of rows to display without
requiring scrolling; for other orientations, it affects the wrapping of
cells.
In VERTICAL
orientation:
Setting this property affects the return value of the
getPreferredScrollableViewportSize()
method, which is used to
calculate the preferred size of an enclosing viewport. See that method's
documentation for more details.
In HORIZONTAL_WRAP
and VERTICAL_WRAP
orientations:
This affects how cells are wrapped. See the documentation of
setLayoutOrientation(int)
for more details.
The default value of this property is 8
.
Calling this method with a negative value results in the property
being set to 0
.
This is a JavaBeans bound property.
visibleRowCount
- an integer specifying the preferred number of
rows to display without requiring scrollinggetVisibleRowCount()
,
getPreferredScrollableViewportSize()
,
setLayoutOrientation(int)
,
JComponent.getVisibleRect()
,
JViewport
public int getLayoutOrientation()
VERTICAL
if the layout is a single column of cells, VERTICAL_WRAP
if the
layout is "newspaper style" with the content flowing vertically then
horizontally, or HORIZONTAL_WRAP
if the layout is "newspaper
style" with the content flowing horizontally then vertically.
layoutOrientation
propertysetLayoutOrientation(int)
public void setLayoutOrientation(int layoutOrientation)
JList
with five cells. Cells can be layed out in one of the following ways:
VERTICAL: 0 1 2 3 4 HORIZONTAL_WRAP: 0 1 2 3 4 VERTICAL_WRAP: 0 3 1 4 2
A description of these layouts follows:
Value | Description |
---|---|
VERTICAL
| Cells are layed out vertically in a single column. |
HORIZONTAL_WRAP
| Cells are layed out horizontally, wrapping to a new row as
necessary. If the visibleRowCount property is less than
or equal to zero, wrapping is determined by the width of the
list; otherwise wrapping is done in such a way as to ensure
visibleRowCount rows in the list.
|
VERTICAL_WRAP
| Cells are layed out vertically, wrapping to a new column as
necessary. If the visibleRowCount property is less than
or equal to zero, wrapping is determined by the height of the
list; otherwise wrapping is done at visibleRowCount rows.
|
The default value of this property is VERTICAL
.
layoutOrientation
- the new layout orientation, one of:
VERTICAL
, HORIZONTAL_WRAP
or VERTICAL_WRAP
IllegalArgumentException
- if layoutOrientation
isn't one of the
allowable valuesgetLayoutOrientation()
,
setVisibleRowCount(int)
,
getScrollableTracksViewportHeight()
,
getScrollableTracksViewportWidth()
public int getFirstVisibleIndex()
componentOrientation
, the first visible
cell is found closest to the list's upper-left corner. In right-to-left
orientation, it is found closest to the upper-right corner.
If nothing is visible or the list is empty, -1
is returned.
Note that the returned cell may only be partially visible.
getLastVisibleIndex()
,
JComponent.getVisibleRect()
public int getLastVisibleIndex()
-1
is returned.
Note that the returned cell may only be partially visible.
getFirstVisibleIndex()
,
JComponent.getVisibleRect()
public void ensureIndexIsVisible(int index)
scrollRectToVisible
with
the bounds of the specified cell. For this method to work, the
JList
must be within a JViewport
.
If the given index is outside the list's range of cells, this method results in nothing.
index
- the index of the cell to make visibleJComponent.scrollRectToVisible(java.awt.Rectangle)
,
JComponent.getVisibleRect()
public void setDragEnabled(boolean b)
true
, and the
list's TransferHandler
needs to be non-null
.
The default value of the dragEnabled
property is false
.
The job of honoring this property, and recognizing a user drag gesture,
lies with the look and feel implementation, and in particular, the list's
ListUI
. When automatic drag handling is enabled, most look and
feels (including those that subclass BasicLookAndFeel
) begin a
drag and drop operation whenever the user presses the mouse button over
an item and then moves the mouse a few pixels. Setting this property to
true
can therefore have a subtle effect on how selections behave.
If a look and feel is used that ignores this property, you can still
begin a drag and drop operation by calling exportAsDrag
on the
list's TransferHandler
.
b
- whether or not to enable automatic drag handling
HeadlessException
- if
b
is true
and
GraphicsEnvironment.isHeadless()
returns true
GraphicsEnvironment.isHeadless()
,
getDragEnabled()
,
JComponent.setTransferHandler(javax.swing.TransferHandler)
,
TransferHandler
public boolean getDragEnabled()
dragEnabled
propertysetDragEnabled(boolean)
public final void setDropMode(DropMode dropMode)
DropMode.USE_SELECTION
.
Usage of one of the other modes is recommended, however, for an
improved user experience. DropMode.ON
, for instance,
offers similar behavior of showing items as selected, but does so without
affecting the actual selection in the list.
JList
supports the following drop modes:
DropMode.USE_SELECTION
DropMode.ON
DropMode.INSERT
DropMode.ON_OR_INSERT
TransferHandler
that accepts drops.
dropMode
- the drop mode to use
IllegalArgumentException
- if the drop mode is unsupported
or null
getDropMode()
,
getDropLocation()
,
JComponent.setTransferHandler(javax.swing.TransferHandler)
,
TransferHandler
public final DropMode getDropMode()
setDropMode(javax.swing.DropMode)
public final JList.DropLocation getDropLocation()
null
if no location is to currently be shown.
This method is not meant for querying the drop location
from a TransferHandler
, as the drop location is only
set after the TransferHandler
's canImport
has returned and has allowed for the location to be shown.
When this property changes, a property change event with name "dropLocation" is fired by the component.
By default, responsibility for listening for changes to this property
and indicating the drop location visually lies with the list's
ListUI
, which may paint it directly and/or install a cell
renderer to do so. Developers wishing to implement custom drop location
painting and/or replace the default cell renderer, may need to honor
this property.
setDropMode(javax.swing.DropMode)
,
TransferHandler.canImport(TransferHandler.TransferSupport)
public int getNextMatch(String prefix, int startIndex, Position.Bias bias)
toString
value
starts with the given prefix.
prefix
- the string to test for a matchstartIndex
- the index for starting the searchbias
- the search direction, either
Position.Bias.Forward or Position.Bias.Backward.
-1
IllegalArgumentException
- if prefix is null
or startIndex is out of boundspublic String getToolTipText(MouseEvent event)
JComponent
's getToolTipText
to first check the cell
renderer component for the cell over which the event occurred, returning
its tooltip text, if any. This implementation allows you to specify
tooltip text on the cell level, by using setToolTipText
on your
cell renderer component.
JList
to properly display the
tooltips of its renderers in this manner, JList
must be a
registered component with the ToolTipManager
. This registration
is done automatically in the constructor. However, if at a later point
JList
is unregistered, by way of a call to
setToolTipText(null)
, tips from the renderers will no longer display.
getToolTipText
in class JComponent
event
- the MouseEvent
to fetch the tooltip text forJComponent.setToolTipText(java.lang.String)
,
JComponent.getToolTipText()
public int locationToIndex(Point location)
getCellBounds
. This method returns -1
if the model is empty
This is a cover method that delegates to the method of the same name
in the list's ListUI
. It returns -1
if the list has
no ListUI
.
location
- the coordinates of the point
-1
public Point indexToLocation(int index)
null
if the index isn't valid.
This is a cover method that delegates to the method of the same name
in the list's ListUI
. It returns null
if the list has
no ListUI
.
index
- the cell index
null
public Rectangle getCellBounds(int index0, int index1)
If the smaller index is outside the list's range of cells, this method
returns null
. If the smaller index is valid, but the larger
index is outside the list's range, the bounds of just the first index
is returned. Otherwise, the bounds of the valid range is returned.
This is a cover method that delegates to the method of the same name
in the list's ListUI
. It returns null
if the list has
no ListUI
.
index0
- the first index in the rangeindex1
- the second index in the range
null
public ListModel getModel()
JList
component.
ListModel
that provides the displayed
list of itemssetModel(javax.swing.ListModel)
public void setModel(ListModel model)
This is a JavaBeans bound property.
model
- the ListModel
that provides the
list of items for display
IllegalArgumentException
- if model
is
null
getModel()
,
clearSelection()
public void setListData(Object[] listData)
ListModel
from an array of objects,
and calls setModel
with this model.
Attempts to pass a null
value to this method results in
undefined behavior and, most likely, exceptions. The created model
references the given array directly. Attempts to modify the array
after invoking this method results in undefined behavior.
listData
- an array of Objects
containing the items to
display in the listsetModel(javax.swing.ListModel)
public void setListData(Vector<?> listData)
ListModel
from a Vector
and calls setModel
with this model.
Attempts to pass a null
value to this method results in
undefined behavior and, most likely, exceptions. The created model
references the given Vector
directly. Attempts to modify the
Vector
after invoking this method results in undefined behavior.
listData
- a Vector
containing the items to
display in the listsetModel(javax.swing.ListModel)
protected ListSelectionModel createSelectionModel()
DefaultListSelectionModel
; called
during construction to initialize the list's selection model
property.
DefaultListSelecitonModel
, used to initialize
the list's selection model property during constructionsetSelectionModel(javax.swing.ListSelectionModel)
,
DefaultListSelectionModel
public ListSelectionModel getSelectionModel()
ListSelectionModel
that maintains the
list's selectionssetSelectionModel(javax.swing.ListSelectionModel)
,
ListSelectionModel
protected void fireSelectionValueChanged(int firstIndex, int lastIndex, boolean isAdjusting)
ListSelectionListener
s added directly to the list
of selection changes made to the selection model. JList
listens for changes made to the selection in the selection model,
and forwards notification to listeners added to the list directly,
by calling this method.
This method constructs a ListSelectionEvent
with this list
as the source, and the specified arguments, and sends it to the
registered ListSelectionListeners
.
firstIndex
- the first index in the range, <= lastIndex
lastIndex
- the last index in the range, >= firstIndex
isAdjusting
- whether or not this is one in a series of
multiple events, where changes are still being madeaddListSelectionListener(javax.swing.event.ListSelectionListener)
,
removeListSelectionListener(javax.swing.event.ListSelectionListener)
,
ListSelectionEvent
,
EventListenerList
public void addListSelectionListener(ListSelectionListener listener)
JList
takes care of listening for selection state
changes in the selection model, and notifies the given listener of
each change. ListSelectionEvent
s sent to the listener have a
source
property set to this list.
listener
- the ListSelectionListener
to addgetSelectionModel()
,
getListSelectionListeners()
public void removeListSelectionListener(ListSelectionListener listener)
listener
- the ListSelectionListener
to removeaddListSelectionListener(javax.swing.event.ListSelectionListener)
,
getSelectionModel()
public ListSelectionListener[] getListSelectionListeners()
ListSelectionListener
s added
to this JList
by way of addListSelectionListener
.
ListSelectionListener
s on this list, or
an empty array if no listeners have been addedaddListSelectionListener(javax.swing.event.ListSelectionListener)
public void setSelectionModel(ListSelectionModel selectionModel)
selectionModel
for the list to a
non-null
ListSelectionModel
implementation. The selection model handles the task of making single
selections, selections of contiguous ranges, and non-contiguous
selections.
This is a JavaBeans bound property.
selectionModel
- the ListSelectionModel
that
implements the selections
IllegalArgumentException
- if selectionModel
is null
getSelectionModel()
public void setSelectionMode(int selectionMode)
The following list describes the accepted selection modes:
ListSelectionModel.SINGLE_SELECTION
-
Only one list index can be selected at a time. In this mode,
setSelectionInterval
and addSelectionInterval
are
equivalent, both replacing the current selection with the index
represented by the second argument (the "lead").
ListSelectionModel.SINGLE_INTERVAL_SELECTION
-
Only one contiguous interval can be selected at a time.
In this mode, addSelectionInterval
behaves like
setSelectionInterval
(replacing the current selection},
unless the given interval is immediately adjacent to or overlaps
the existing selection, and can be used to grow the selection.
ListSelectionModel.MULTIPLE_INTERVAL_SELECTION
-
In this mode, there's no restriction on what can be selected.
This mode is the default.
selectionMode
- the selection mode
IllegalArgumentException
- if the selection mode isn't
one of those allowedgetSelectionMode()
public int getSelectionMode()
setSelectionMode(int)
public int getAnchorSelectionIndex()
ListSelectionModel.getAnchorSelectionIndex()
public int getLeadSelectionIndex()
ListSelectionModel.getLeadSelectionIndex()
public int getMinSelectionIndex()
-1
if the selection
is empty. This is a cover method that delegates to the method of the same
name on the list's selection model.
-1
ListSelectionModel.getMinSelectionIndex()
public int getMaxSelectionIndex()
-1
if the selection
is empty. This is a cover method that delegates to the method of the same
name on the list's selection model.
ListSelectionModel.getMaxSelectionIndex()
public boolean isSelectedIndex(int index)
true
if the specified index is selected,
else false
. This is a cover method that delegates to the method
of the same name on the list's selection model.
index
- index to be queried for selection state
true
if the specified index is selected,
else false
ListSelectionModel.isSelectedIndex(int)
,
setSelectedIndex(int)
public boolean isSelectionEmpty()
true
if nothing is selected, else false
.
This is a cover method that delegates to the method of the same
name on the list's selection model.
true
if nothing is selected, else false
ListSelectionModel.isSelectionEmpty()
,
clearSelection()
public void clearSelection()
isSelectionEmpty
will return true
. This is a cover method that delegates to the
method of the same name on the list's selection model.
public void setSelectionInterval(int anchor, int lead)
anchor
and lead
indices are included. anchor
doesn't have to be less than or
equal to lead
. This is a cover method that delegates to the
method of the same name on the list's selection model.
Refer to the documentation of the selection model class being used
for details on how values less than 0
are handled.
anchor
- the first index to selectlead
- the last index to selectListSelectionModel.setSelectionInterval(int, int)
,
DefaultListSelectionModel.setSelectionInterval(int, int)
,
createSelectionModel()
,
addSelectionInterval(int, int)
,
removeSelectionInterval(int, int)
public void addSelectionInterval(int anchor, int lead)
anchor
and lead
indices are
included. anchor
doesn't have to be less than or
equal to lead
. This is a cover method that delegates to the
method of the same name on the list's selection model.
Refer to the documentation of the selection model class being used
for details on how values less than 0
are handled.
anchor
- the first index to add to the selectionlead
- the last index to add to the selectionListSelectionModel.addSelectionInterval(int, int)
,
DefaultListSelectionModel.addSelectionInterval(int, int)
,
createSelectionModel()
,
setSelectionInterval(int, int)
,
removeSelectionInterval(int, int)
public void removeSelectionInterval(int index0, int index1)
index0
and index1
indices are removed. index0
doesn't have to be less than or
equal to index1
. This is a cover method that delegates to the
method of the same name on the list's selection model.
Refer to the documentation of the selection model class being used
for details on how values less than 0
are handled.
index0
- the first index to remove from the selectionindex1
- the last index to remove from the selectionListSelectionModel.removeSelectionInterval(int, int)
,
DefaultListSelectionModel.removeSelectionInterval(int, int)
,
createSelectionModel()
,
setSelectionInterval(int, int)
,
addSelectionInterval(int, int)
public void setValueIsAdjusting(boolean b)
valueIsAdjusting
property. When
true
, upcoming changes to selection should be considered part
of a single change. This property is used internally and developers
typically need not call this method. For example, when the model is being
updated in response to a user drag, the value of the property is set
to true
when the drag is initiated and set to false
when the drag is finished. This allows listeners to update only
when a change has been finalized, rather than handling all of the
intermediate values.
You may want to use this directly if making a series of changes that should be considered part of a single change.
This is a cover method that delegates to the method of the same name on
the list's selection model. See the documentation for
ListSelectionModel.setValueIsAdjusting(boolean)
for
more details.
b
- the new value for the propertyListSelectionModel.setValueIsAdjusting(boolean)
,
ListSelectionEvent.getValueIsAdjusting()
,
getValueIsAdjusting()
public boolean getValueIsAdjusting()
isAdjusting
property.
This is a cover method that delegates to the method of the same name on the list's selection model.
isAdjusting
property.setValueIsAdjusting(boolean)
,
ListSelectionModel.getValueIsAdjusting()
public int[] getSelectedIndices()
removeSelectionInterval(int, int)
,
addListSelectionListener(javax.swing.event.ListSelectionListener)
public void setSelectedIndex(int index)
setSelectionInterval
on the selection model. Refer to the
documentation for the selection model class being used for details on
how values less than 0
are handled.
index
- the index of the cell to selectListSelectionModel.setSelectionInterval(int, int)
,
isSelectedIndex(int)
,
addListSelectionListener(javax.swing.event.ListSelectionListener)
public void setSelectedIndices(int[] indices)
addSelectionInterval
on the selection model to add the indices.
Refer to the documentation of the selection model class being used for
details on how values less than 0
are handled.
indices
- an array of the indices of the cells to select,
non-null
NullPointerException
- if the given array is null
ListSelectionModel.addSelectionInterval(int, int)
,
isSelectedIndex(int)
,
addListSelectionListener(javax.swing.event.ListSelectionListener)
public Object[] getSelectedValues()
isSelectedIndex(int)
,
getModel()
,
addListSelectionListener(javax.swing.event.ListSelectionListener)
public int getSelectedIndex()
-1
if there is
no selection.
This method is a cover that delegates to getMinSelectionIndex
.
getMinSelectionIndex()
,
addListSelectionListener(javax.swing.event.ListSelectionListener)
public Object getSelectedValue()
null
if there is no selection.
This is a convenience method that simply returns the model value for
getMinSelectionIndex
.
getMinSelectionIndex()
,
getModel()
,
addListSelectionListener(javax.swing.event.ListSelectionListener)
public void setSelectedValue(Object anObject, boolean shouldScroll)
anObject
- the object to selectshouldScroll
- true
if the list should scroll to display
the selected object, if one exists; otherwise false
public Dimension getPreferredScrollableViewportSize()
visibleRowCount
rows. The value returned by this method depends on the layout
orientation:
VERTICAL
:
This is trivial if both fixedCellWidth
and fixedCellHeight
have been set (either explicitly or by specifying a prototype cell value).
The width is simply the fixedCellWidth
plus the list's horizontal
insets. The height is the fixedCellHeight
multiplied by the
visibleRowCount
, plus the list's vertical insets.
If either fixedCellWidth
or fixedCellHeight
haven't been
specified, heuristics are used. If the model is empty, the width is
the fixedCellWidth
, if greater than 0
, or a hard-coded
value of 256
. The height is the fixedCellHeight
multiplied
by visibleRowCount
, if fixedCellHeight
is greater than
0
, otherwise it is a hard-coded value of 16
multiplied by
visibleRowCount
.
If the model isn't empty, the width is the preferred size's width,
typically the width of the widest list element. The height is the
fixedCellHeight
multiplied by the visibleRowCount
,
plus the list's vertical insets.
VERTICAL_WRAP
or HORIZONTAL_WRAP
:
This method simply returns the value from getPreferredSize
.
The list's ListUI
is expected to override getPreferredSize
to return an appropriate value.
getPreferredScrollableViewportSize
in interface Scrollable
visibleRowCount
rowsgetPreferredScrollableViewportSize()
,
setPrototypeCellValue(java.lang.Object)
public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction)
For horizontal scrolling, if the layout orientation is VERTICAL
,
then the list's font size is returned (or 1
if the font is
null
).
getScrollableUnitIncrement
in interface Scrollable
visibleRect
- the view area visible within the viewportorientation
- SwingConstants.HORIZONTAL
or
SwingConstants.VERTICAL
direction
- less or equal to zero to scroll up/back,
greater than zero for down/forward
IllegalArgumentException
- if visibleRect
is null
, or
orientation
isn't one of SwingConstants.VERTICAL
or
SwingConstants.HORIZONTAL
getScrollableBlockIncrement(java.awt.Rectangle, int, int)
,
Scrollable.getScrollableUnitIncrement(java.awt.Rectangle, int, int)
public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction)
For vertical scrolling, the following rules are used:
visibleRect.height
if the list is empty
For horizontal scrolling, when the layout orientation is either
VERTICAL_WRAP
or HORIZONTAL_WRAP
:
visibleRect.width
if the list is empty
For horizontal scrolling and VERTICAL
orientation,
returns visibleRect.width
.
Note that the value of visibleRect
must be the equal to
this.getVisibleRect()
.
getScrollableBlockIncrement
in interface Scrollable
visibleRect
- the view area visible within the viewportorientation
- SwingConstants.HORIZONTAL
or
SwingConstants.VERTICAL
direction
- less or equal to zero to scroll up/back,
greater than zero for down/forward
IllegalArgumentException
- if visibleRect
is null
, or
orientation
isn't one of SwingConstants.VERTICAL
or
SwingConstants.HORIZONTAL
getScrollableUnitIncrement(java.awt.Rectangle, int, int)
,
Scrollable.getScrollableBlockIncrement(java.awt.Rectangle, int, int)
public boolean getScrollableTracksViewportWidth()
true
if this JList
is displayed in a
JViewport
and the viewport is wider than the list's
preferred width, or if the layout orientation is HORIZONTAL_WRAP
and visibleRowCount <= 0
; otherwise returns false
.
If false
, then don't track the viewport's width. This allows
horizontal scrolling if the JViewport
is itself embedded in a
JScrollPane
.
getScrollableTracksViewportWidth
in interface Scrollable
Scrollable.getScrollableTracksViewportWidth()
public boolean getScrollableTracksViewportHeight()
true
if this JList
is displayed in a
JViewport
and the viewport is taller than the list's
preferred height, or if the layout orientation is VERTICAL_WRAP
and visibleRowCount <= 0
; otherwise returns false
.
If false
, then don't track the viewport's height. This allows
vertical scrolling if the JViewport
is itself embedded in a
JScrollPane
.
getScrollableTracksViewportHeight
in interface Scrollable
Scrollable.getScrollableTracksViewportHeight()
protected String paramString()
String
representation of this JList
.
This method is intended to be used only for debugging purposes,
and the content and format of the returned String
may vary
between implementations. The returned String
may be empty,
but may not be null
.
paramString
in class JComponent
String
representation of this JList
.public AccessibleContext getAccessibleContext()
AccessibleContext
associated with this JList
.
For JList
, the AccessibleContext
takes the form of an
AccessibleJList
.
A new AccessibleJList
instance is created if necessary.
getAccessibleContext
in interface Accessible
getAccessibleContext
in class JComponent
AccessibleJList
that serves as the
AccessibleContext
of this JList
|
Java™ Platform Standard Ed. 6 |
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