Class com.sun.java.swing.JComponent
java.lang.Object
|
+----java.awt.Component
|
+----java.awt.Container
|
+----com.sun.java.swing.JComponent
- public abstract class JComponent
- extends Container
- implements Serializable
The base class for the Swing components. JComponent provides:
- A "pluggable look and feel" (l&f) that can be specified by the
programmer or (optionally) selected by the user at runtime.
- Components that are designed to be combined and extended in order
to create custom components.
- Comprehensive keystroke-handling that works with nested components.
- Action objects, for single-point control of program actions initiated
by multiple components.
- A border property that implicitly defines the component's insets.
- The ability to set the preferred, minimim, and maximum size for a
component.
- ToolTips -- short descriptions that pop up when the cursor lingers
over a component.
- Autoscrolling -- automatic scrolling in a list, table, or tree that
occurs when the user is dragging the mouse.
- Simple, easy dialog construction using static methods in the JOptionPane
class that let you display information and query the user.
- Slow-motion graphics rendering using debugGraphics so you can see
what is being displayed on screen and whether or not it is being
overwritten.
- Support for Accessibility.
- Support for international Localization.
Keystroke Handling
The JComponent architecture makes it easy to handle keyboard events
in nested components. You register interest in a particular combination
of keystrokes by creating a KeyStroke object and registering it with the
component. When you register the keystroke combination and its associated
action, you also specify one of the following conditions to determine
when the action is initiated:
- The component has the focus.
- A child or grandchild of the component has the focus.
You can use this capability to define global actions
for a composite component. For example, a tree control could
act on the Plus key to expand all elements in the tree, as long
as any component in the tree has the focus.
- The window the component is in has the focus.
In other words, if the component is a child or grandchild of
a window, and any component in that window has the focus, then
the component receives the event. You can use this
capability to direct the keystroke combination Alt+C to the Cancel
button in a dialog, for example, as long any component in the dialog
has the focus.
Action objects
Action-interface objects provide a single point of control for program
actions. For example, a toolbar icon and a menu item can reference the
same Action object. When the Action object is disabled, the GUI items that
reference it are automatically disabled. The Action interface extends
ActionListener, specifying an enabled property as well as properties for
text-descriptions and graphic icons.
Compound Borders
Insets (the space between the edges of the component and the area
it is drawn in) can be specified with a blank border. In addition, many
border styles are available, which can be combined to create compound
borders.
Simple Dialog Construction
The JOptionPane class provides a variety of static methods that you
can invoke to create and display both message dialogs and user-choice
dialogs in a variety of formats. The "message" displayed in the
dialog can be a string, a string-generating object, or an arbitrary
component. You can also replace the choice-buttons with components
you specify for user-selections.
For example, the following line creates a simple message dialog that
requires the user's confirmation:
JOptionPane.showMessageDialog(null, "The file will be deleted.");
Additional options are described in the JOptionPane class.
Support for Accessibility
Swing has built-in support for developers to make
products that are compatible with Assistive Technologies (for
alternative interfaces like, for example, braille.) All of the Swing
components implement interface Accessible.
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 Swing1.0 applications. It will
not be possible to load serialized Swing1.0 objects with future releases
of Swing. The JDK1.2 release of Swing will be the compatibility
baseline for the serialized form of Swing objects.
- See Also:
- KeyStroke, Action, setBorder, registerKeyboardAction, JOptionPane, setDebugGraphicsOptions, setToolTipText, setAutoscrolls
Variable Index
- accessibleContext
- --- Accessibility Support ---
JComponent will contain all of the methods in interface Accessible,
though it won't actally implement the interface - that will be up
to the individual objects which extend JComponent.
- listenerList
-
- TOOL_TIP_TEXT_KEY
- The comment to display when the cursor is over the component,
also known as a "value tip", "flyover help", or "flyover label".
- ui
-
- UNDEFINED_CONDITION
-
Constant used by some of the apis to mean that no condition is defined.
- WHEN_ANCESTOR_OF_FOCUSED_COMPONENT
-
Constant used for registerKeyboardAction() which
means that the comand should be invoked when the receiving
component is an ancestor of the focused component or is
itself the focused component.
- WHEN_FOCUSED
-
Constant used for registerKeyboardAction() which
means that the command should be invoked when
the component has the focus.
- WHEN_IN_FOCUSED_WINDOW
- Constant used for registerKeyboardAction() which
means that the command should be invoked when
the receiving component is in the window that has the focus
or is itself the focused component.
Constructor Index
- JComponent()
- Default JComponent constructor.
Method Index
- addAncestorListener(AncestorListener)
- Registers listener so that it will receive AncestorEvents
when it or any of its ancestors move or are made visible / invisible.
- addNotify()
- Notification to this component that it now has a parent component.
- addPropertyChangeListener(PropertyChangeListener)
- Add a PropertyChangeListener to the listener list.
- addVetoableChangeListener(VetoableChangeListener)
- Add a VetoableChangeListener to the listener list.
- computeVisibleRect(Rectangle)
- Returns the Component's "visible rect rectangle" - the
intersection of the visible rectangles for this component
and all of its ancestors.
- contains(int, int)
- Give the UI delegate an opportunity to define the precise
shape of this component for the sake of mouse processing.
- createToolTip()
- Returns the instance of JToolTip that should be used to display the tooltip.
- firePropertyChange(String, boolean, boolean)
-
- firePropertyChange(String, byte, byte)
-
- firePropertyChange(String, char, char)
-
- firePropertyChange(String, double, double)
-
- firePropertyChange(String, float, float)
-
- firePropertyChange(String, int, int)
-
- firePropertyChange(String, long, long)
-
- firePropertyChange(String, Object, Object)
- Support for reporting bound property changes.
- firePropertyChange(String, short, short)
-
- fireVetoableChange(String, Object, Object)
- Support for reporting constrained property changes.
- getAccessibleContext()
- Get the AccessibleContext associated with this JComponent
- getActionForKeyStroke(KeyStroke)
-
Return the object that will perform the action registered for a
given keystroke.
- getAlignmentX()
-
- getAlignmentY()
-
- getAutoscrolls()
- Returns true if this component automatically scrolls its
contents when dragged, (when contained in a component that supports
scrolling, like JViewport
- getBorder()
- Returns the border of this component or null if no border is
currently set.
- getBounds(Rectangle)
-
Store the bounds of this component into "return value" rv and
return rv.
- getClientProperty(Object)
- A convenience method for looking up a property value.
- getComponentGraphics(Graphics)
- Returns the graphics object used to paint this component.
- getConditionForKeyStroke(KeyStroke)
-
Return the condition that determines whether a registered action
occurs in response to the specified keystroke.
- getDebugGraphicsOptions()
- Returns the state of graphics debugging.
- getGraphics()
- Returns this component's graphics context, which lets you draw
on a component.
- getHeight()
-
Return the current height of this component.
- getInsets()
- If a border has been set on this component, returns the
border's insets, else calls super.getInsets.
- getLocation(Point)
- Store the x,y origin of this component into "return value" rv
and return rv.
- getMaximumSize()
- If the maximumSize has been set to a non-null value
just return it.
- getMinimumSize()
- If the minimumSize has been set to a non-null value
just return it.
- getNextFocusableComponent()
- Return the next focusable component or null if the focus manager
should choose the next focusable component automatically
- getPreferredSize()
- If the preferredSize has been set to a non-null value
just return it.
- getRegisteredKeyStrokes()
-
Return the KeyStrokes that will initiate registered actions.
- getRootPane()
- Return the receiving component root pane
- getSize(Dimension)
- Store the width/height of this component into "return value" rv
and return rv.
- getToolTipLocation(MouseEvent)
- Return the tooltip location in the receiving component coordinate system
If null is returned, Swing will choose a location.
- getToolTipText()
- Return the tooltip string that has been set with setToolTipText()
- getToolTipText(MouseEvent)
- Returns the string to be used as the tooltip for event.
- getTopLevelAncestor()
- Returns the top-level ancestor of this component (either the
containing Window or Applet), or null if this component has not
been added to any container.
- getUIClassID()
- Return the UIDefaults key used to look up the name of the
swing.plaf.ComponentUI class that defines the look and feel
for this component.
- getVisibleRect()
- Returns the Component's "visible rectangle" - the
intersection of this components visible rectangle:
new Rectangle(0, 0, getWidth(), getHeight());
and all of its ancestors visible Rectangles.
- getWidth()
-
Return the current width of this component.
- getX()
-
Return the current x coordinate of the components origin.
- getY()
-
Return the current y coordinate of the components origin.
- grabFocus()
- Set the focus on the receiving component.
- hasFocus()
- Returns true if this Component has the keyboard focus.
- isDoubleBuffered()
- Return whether the receiving component should use a buffer to paint.
- isFocusCycleRoot()
-
Override this method and return true if your component is the root of
of a component tree with its own focus cycle.
- isFocusTraversable()
- Identifies whether or not this component can receive the focus.
- isLightweightComponent(Component)
- Returns true if this component is a lightweight, i.e.
- isManagingFocus()
- Override this method and return true if your JComponent manages focus.
- isOpaque()
- Returns true if this component is completely opaque.
- isOptimizedDrawingEnabled()
- Returns true if this component tiles its children, i.e.
- isPaintingTile()
- Returns true if the receiving component is currently painting a tile.
- isRequestFocusEnabled()
- Return whether the receiving component can obtain the focus by
calling requestFocus
- isValidateRoot()
-
If this method returns true, revalidate() calls by descendants of
this component will cause the entire tree beginning with this root
to be validated.
- paint(Graphics)
- This method is invoked by Swing to draw components.
- paintBorder(Graphics)
- Paint the component's border.
- paintChildren(Graphics)
- Paint this component's children.
- paintComponent(Graphics)
- If the UI delegate is non-null, call its paint
method.
- paintImmediately(int, int, int, int)
-
Paint the specified region in this component and all of its
descendants that overlap the region, immediately.
- paintImmediately(Rectangle)
-
Paint the specified region now.
- processComponentKeyEvent(KeyEvent)
- Process any key events that the component itself
recognizes.
- processFocusEvent(FocusEvent)
-
- processKeyEvent(KeyEvent)
- Override processKeyEvent to process events
- processMouseMotionEvent(MouseEvent)
-
- putClientProperty(Object, Object)
- A convenience method for storing up a property value.
- registerKeyboardAction(ActionListener, KeyStroke, int)
- Calls registerKeyboardAction(ActionListener,String,KeyStroke,condition) with a null command.
- registerKeyboardAction(ActionListener, String, KeyStroke, int)
- Register a new keyboard action.
- removeAncestorListener(AncestorListener)
- Unregisters listener so that it will no longer receive
AncestorEvents
This method will migrate to java.awt.Component in the next major JDK release
- removeNotify()
- Notification to this component that it no longer has a parent component.
- removePropertyChangeListener(PropertyChangeListener)
- Remove a PropertyChangeListener from the listener list.
- removeVetoableChangeListener(VetoableChangeListener)
- Remove a VetoableChangeListener from the listener list.
- repaint(long, int, int, int, int)
- Adds the specified region to the dirty region list if the component
is showing.
- repaint(Rectangle)
- Adds the specified region to the dirty region list if the component
is showing.
- requestDefaultFocus()
-
Request the focus for the component that should have the focus
by default.
- requestFocus()
- Set focus on the receiving component if isRequestFocusEnabled returns true
- resetKeyboardActions()
-
Unregister all keyboard actions
- reshape(int, int, int, int)
-
Moves and resizes this component.
- revalidate()
- Support for deferred automatic layout.
- scrollRectToVisible(Rectangle)
- Forwards the scrollRectToVisible() message to the JComponent's
parent.
- setAlignmentX(float)
- Set the value of the alignmentX property.
- setAlignmentY(float)
- Set the value of the alignmentY property.
- setAutoscrolls(boolean)
- If true this component will automatically scroll its contents when
dragged, if contained in a component that supports scrolling, such as
JViewport
- setBorder(Border)
- Sets the border of this component.
- setBounds(Rectangle)
-
Moves and resizes this component.
- setDebugGraphicsOptions(int)
- Enables or disables diagnostic information about every graphics
operation performed within the component or one of its children.
- setDoubleBuffered(boolean)
- Set whether the receiving component should use a buffer to paint.
- setMaximumSize(Dimension)
- Sets the maximumSize of this component to a constant
value.
- setMinimumSize(Dimension)
- Sets the minimumSize of this component to a constant
value.
- setNextFocusableComponent(Component)
- Specifies the next component to get the focus after this one,
for example, when the tab key is pressed.
- setOpaque(boolean)
- If true the components background will be filled with the
background color.
- setPreferredSize(Dimension)
- Set the preferred size of the receiving component.
- setRequestFocusEnabled(boolean)
-
Set whether the receiving component can obtain the focus by
calling requestFocus.
- setToolTipText(String)
- Registers the text to display in a tool tip.
- setUI(ComponentUI)
- Set the look and feel delegate for this component.
- setVisible(boolean)
-
- unregisterKeyboardAction(KeyStroke)
-
Unregister a keyboard action.
- update(Graphics)
- Calls paint(g).
- updateUI()
- Resets the UI property to a value from the current look and feel.
Variables
ui
protected ComponentUI ui
listenerList
protected EventListenerList listenerList
WHEN_FOCUSED
public static final int WHEN_FOCUSED
- Constant used for registerKeyboardAction() which
means that the command should be invoked when
the component has the focus.
WHEN_ANCESTOR_OF_FOCUSED_COMPONENT
public static final int WHEN_ANCESTOR_OF_FOCUSED_COMPONENT
- Constant used for registerKeyboardAction() which
means that the comand should be invoked when the receiving
component is an ancestor of the focused component or is
itself the focused component.
WHEN_IN_FOCUSED_WINDOW
public static final int WHEN_IN_FOCUSED_WINDOW
- Constant used for registerKeyboardAction() which
means that the command should be invoked when
the receiving component is in the window that has the focus
or is itself the focused component.
UNDEFINED_CONDITION
public static final int UNDEFINED_CONDITION
- Constant used by some of the apis to mean that no condition is defined.
TOOL_TIP_TEXT_KEY
public static final String TOOL_TIP_TEXT_KEY
- The comment to display when the cursor is over the component,
also known as a "value tip", "flyover help", or "flyover label".
accessibleContext
protected AccessibleContext accessibleContext
- --- Accessibility Support ---
JComponent will contain all of the methods in interface Accessible,
though it won't actally implement the interface - that will be up
to the individual objects which extend JComponent.
Constructors
JComponent
public JComponent()
- Default JComponent constructor. This constructor does
no initialization beyond calling the Container constructor,
e.g. the initial layout manager is null.
Methods
updateUI
public void updateUI()
- Resets the UI property to a value from the current look and feel.
JComponent subclasses must override this method like this:
public void updateUI() {
setUI((SliderUI)UIManager.getUI(this);
}
- See Also:
- setUI, getLookAndFeel, getUI
setUI
protected void setUI(ComponentUI newUI)
- Set the look and feel delegate for this component.
JComponent subclasses generally override this method
to narrow the argument type, e.g. in JSlider:
public void setUI(SliderUI newUI) {
super.setUI(newUI);
}
Additionaly JComponent subclasses must provide a getUI
method that returns the correct type, e.g.
public SliderUI getUI() {
return (SliderUI)ui;
}
- See Also:
- updateUI, getLookAndFeel, getUI
getUIClassID
public String getUIClassID()
- Return the UIDefaults key used to look up the name of the
swing.plaf.ComponentUI class that defines the look and feel
for this component. Most applications will never need to
call this method. Subclasses of JComponent that support
pluggable look and feel should override this method to
return the name of the ComponentUI subclass that defines
their look and feel.
- Returns:
- The name of a ComponentUI subclass.
- See Also:
- getUI
getComponentGraphics
protected Graphics getComponentGraphics(Graphics g)
- Returns the graphics object used to paint this component.
If DebugGraphics is turned on we create a new DebugGraphics
object if neccessary otherwise we just configure the
specified graphics objects foreground and font.
- Returns:
- A Graphics object configured for this component
paintComponent
protected void paintComponent(Graphics g)
- If the UI delegate is non-null, call its paint
method. We pass the delegate a copy of the Graphics
object to protect the rest of the paint code from
irrevocable changes (e.g. Graphics.translate()).
- See Also:
- paint
paintChildren
protected void paintChildren(Graphics g)
- Paint this component's children.
If shouldUseBuffer is true, no component ancestor has a buffer and
the component children can use a buffer if they have one.
Otherwise, one ancestor has a buffer currently in use and children
should not use a buffer to paint.
- See Also:
- paint, paint
paintBorder
protected void paintBorder(Graphics g)
- Paint the component's border.
- See Also:
- paint, setBorder
update
public void update(Graphics g)
- Calls paint(g). Doesn't clear the background but see
ComponentUI.update() which is called by paintComponent.
- Overrides:
- update in class Container
- See Also:
- paint, paintComponent, ComponentUI
paint
public void paint(Graphics g)
- This method is invoked by Swing to draw components.
Applications should not invoke paint directly,
but should instead use the
repaint
method to
schedule the component for redrawing.
This method actually delegates the work of painting to three
protected methods: paintComponent
, paintBorder
,
and paintChildren
. They're called in the order
listed to ensure that children appear on top of component itself.
Generally speaking, the component and its children should not
paint in the insets area allocated to the border. Subclasses can
just override this method, as always. A subclass that just
wants to specialize the UI (look and feel) delegates paint
method should just override paintComponent
.
- Overrides:
- paint in class Container
- See Also:
- paintComponent, paintBorder, paintChildren, getComponentGraphics, repaint
isPaintingTile
public boolean isPaintingTile()
- Returns true if the receiving component is currently painting a tile.
If this method returns true, paint will be called again for another
tile. This method returns false if you are not painting a tile or
if the last tile is painted.
Use this method to keep some state you might need between tiles.
isFocusCycleRoot
public boolean isFocusCycleRoot()
- Override this method and return true if your component is the root of
of a component tree with its own focus cycle.
isManagingFocus
public boolean isManagingFocus()
- Override this method and return true if your JComponent manages focus.
If your component manages focus, the focus manager will handle your
component's children. All key event will be sent to your key listener
including TAB and SHIFT+TAB. CONTROL + TAB and CONTROL + SHIFT + TAB
will move the focus to the next / previous component.
setNextFocusableComponent
public void setNextFocusableComponent(Component aComponent)
- Specifies the next component to get the focus after this one,
for example, when the tab key is pressed. Invoke this method
to override the default focus-change sequence.
getNextFocusableComponent
public Component getNextFocusableComponent()
- Return the next focusable component or null if the focus manager
should choose the next focusable component automatically
setRequestFocusEnabled
public void setRequestFocusEnabled(boolean aFlag)
- Set whether the receiving component can obtain the focus by
calling requestFocus. The default value is true.
Note: Setting this property to false will not prevent the focus
manager from setting the focus to this component, it will prevent
the component from getting the focus when the focus is requested
explicitly. Override isFocusTraversable and return false if the
component should never get the focus.
isRequestFocusEnabled
public boolean isRequestFocusEnabled()
- Return whether the receiving component can obtain the focus by
calling requestFocus
- See Also:
- setRequestFocusEnabled
requestFocus
public void requestFocus()
- Set focus on the receiving component if isRequestFocusEnabled returns true
- Overrides:
- requestFocus in class Component
grabFocus
public void grabFocus()
- Set the focus on the receiving component. This method is for focus managers, you
rarely want to call this method, use requestFocus() enstead.
setPreferredSize
public void setPreferredSize(Dimension preferredSize)
- Set the preferred size of the receiving component.
if
preferredSize
is null, the UI will
be asked for the preferred size
getPreferredSize
public Dimension getPreferredSize()
- If the preferredSize has been set to a non-null value
just return it. If the UI delegates getPreferredSize()
method returns a non null then value return that, otherwise
defer to the components layout manager.
- Returns:
- the value of the preferredSize property.
- Overrides:
- getPreferredSize in class Container
- See Also:
- setPreferredSize
setMaximumSize
public void setMaximumSize(Dimension maximumSize)
- Sets the maximumSize of this component to a constant
value. Subsequent calls to getMaximumSize will always
return this value, the components UI will not be asked
to compute it. Setting the maximumSize to null
restores the default behavior.
- See Also:
- getMaximumSize
getMaximumSize
public Dimension getMaximumSize()
- If the maximumSize has been set to a non-null value
just return it. If the UI delegates getMaximumSize()
method returns a non null value then return that, otherwise
defer to the components layout manager.
- Returns:
- the value of the maximumSize property.
- Overrides:
- getMaximumSize in class Container
- See Also:
- setMaximumSize
setMinimumSize
public void setMinimumSize(Dimension minimumSize)
- Sets the minimumSize of this component to a constant
value. Subsequent calls to getMinimumSize will always
return this value, the components UI will not be asked
to compute it. Setting the minimumSize to null
restores the default behavior.
- See Also:
- getMinimumSize
getMinimumSize
public Dimension getMinimumSize()
- If the minimumSize has been set to a non-null value
just return it. If the UI delegates getMinimumSize()
method returns a non null value then return that, otherwise
defer to the components layout manager.
- Returns:
- the value of the minimumSize property.
- Overrides:
- getMinimumSize in class Container
- See Also:
- setMinimumSize
contains
public boolean contains(int x,
int y)
- Give the UI delegate an opportunity to define the precise
shape of this component for the sake of mouse processing.
- Returns:
- true if this component logically contains x,y.
- Overrides:
- contains in class Component
- See Also:
- contains
setBorder
public void setBorder(Border border)
- Sets the border of this component. The Border object is
responsible for defining the insets for the component
(overriding any insets set directly on the component) and
for optionally rendering any border decorations within the
bounds of those insets. Borders should be used (rather
than insets) for creating both decorative and non-decorative
(e.g. margins and padding) regions for a swing component.
Compound borders can be used to nest multiple borders within a
single component.
This is a bound property.
- Parameters:
- border - the border to be rendered for this component
- See Also:
- Border, CompoundBorder
getBorder
public Border getBorder()
- Returns the border of this component or null if no border is
currently set.
- Returns:
- the border object for this component
- See Also:
- setBorder
getInsets
public Insets getInsets()
- If a border has been set on this component, returns the
border's insets, else calls super.getInsets.
- Returns:
- the value of the insets property.
- Overrides:
- getInsets in class Container
- See Also:
- setBorder
getAlignmentY
public float getAlignmentY()
- Returns:
- the value of the alignmentY property.
- Overrides:
- getAlignmentY in class Container
- See Also:
- setAlignmentY, getAlignmentY
setAlignmentY
public void setAlignmentY(float alignmentY)
- Set the value of the alignmentY property.
- See Also:
- getAlignmentY
getAlignmentX
public float getAlignmentX()
- Returns:
- the value of the alignmentX property.
- Overrides:
- getAlignmentX in class Container
- See Also:
- setAlignmentX, getAlignmentX
setAlignmentX
public void setAlignmentX(float alignmentX)
- Set the value of the alignmentX property.
- See Also:
- getAlignmentX
getGraphics
public Graphics getGraphics()
- Returns this component's graphics context, which lets you draw
on a component. Use this method get a Graphics object and
then invoke oeprations on that object to draw on the component.
- Overrides:
- getGraphics in class Component
setDebugGraphicsOptions
public void setDebugGraphicsOptions(int debugOptions)
- Enables or disables diagnostic information about every graphics
operation performed within the component or one of its children. The
value of debugOptions determines how the component should
display this information:
- DebugGraphics.LOG_OPTION - causes a text message to be printed.
- DebugGraphics.FLASH_OPTION - causes the drawing to flash several
times.
- DebugGraphics.BUFFERED_OPTION - creates an ExternalWindow that
displays the operations performed on the View's offscreen buffer.
debug is bitwise OR'd into the current value.
DebugGraphics.NONE_OPTION disables debugging.
A value of 0 causes no changes to the debugging options.
getDebugGraphicsOptions
public int getDebugGraphicsOptions()
- Returns the state of graphics debugging.
- See Also:
- setDebugGraphicsOptions
registerKeyboardAction
public void registerKeyboardAction(ActionListener anAction,
String aCommand,
KeyStroke aKeyStroke,
int aCondition)
- Register a new keyboard action.
anAction will be invoked if a key event matching aKeyStroke occurs
and aCondition is verified. The KeyStroke object defines a
particular combination of a keyboard key and one or more modifiers
(alt, shift, ctrl, meta).
The aCommand will be set in the delivered event if specified.
The Condition can be one of:
- WHEN_FOCUSED
- The action will be invoked only when the keystroke occurs
while the component has the focus.
- WHEN_IN_FOCUSED_WINDOW
- The action will be invoked when the keystroke occurs while
the component has the focus or if the component is in the
window that has the focus. Note that the component need not
be an immediate descendent of the window -- it can be
anywhere in the window's containment hierarchy. In other
words, whenever any component in the window has the focus,
the action registered with this component is invoked.
- WHEN_ANCESTOR_OF_FOCUSED_COMPONENT
- The action will be invoked when the keystroke occurs while the
component has the focus or if the component is an ancestor of
the component that has the focus.
The combination of keystrokes and conditions lets you define high
level (semantic) action events for a specified keystroke+modifier
combination (using the KeyStroke class) and direct to a parent or
child of a component that has the focus, or to the component itself.
In other words, in any hierarchical structure of components, an
arbitrary key-combination can be immediately directed to the
appropriate component in the hierarchy, and cause a specific method
to be invoked (usually by way of adapter objects).
If an action has already been registered for the receiving
container, with the same charCode and the same modifiers,
anAction will replace the action.
- See Also:
- KeyStroke
registerKeyboardAction
public void registerKeyboardAction(ActionListener anAction,
KeyStroke aKeyStroke,
int aCondition)
- Calls registerKeyboardAction(ActionListener,String,KeyStroke,condition) with a null command.
unregisterKeyboardAction
public void unregisterKeyboardAction(KeyStroke aKeyStroke)
- Unregister a keyboard action.
- See Also:
- registerKeyboardAction
getRegisteredKeyStrokes
public KeyStroke[] getRegisteredKeyStrokes()
- Return the KeyStrokes that will initiate registered actions.
- Returns:
- an array of KeyStroke objects
- See Also:
- registerKeyboardAction
getConditionForKeyStroke
public int getConditionForKeyStroke(KeyStroke aKeyStroke)
- Return the condition that determines whether a registered action
occurs in response to the specified keystroke.
- Returns:
- the action-keystroke condition
- See Also:
- registerKeyboardAction
getActionForKeyStroke
public ActionListener getActionForKeyStroke(KeyStroke aKeyStroke)
- Return the object that will perform the action registered for a
given keystroke.
- Returns:
- the ActionListener object invoked when the keystroke occurs
- See Also:
- registerKeyboardAction
resetKeyboardActions
public void resetKeyboardActions()
- Unregister all keyboard actions
- See Also:
- registerKeyboardAction
requestDefaultFocus
public boolean requestDefaultFocus()
- Request the focus for the component that should have the focus
by default. The default implementation will recursively request
the focus on the first component that is focus-traversable.
- Returns:
- false if the focus has not been set, otherwise
return true
setVisible
public void setVisible(boolean aFlag)
- Overrides:
- setVisible in class Component
isFocusTraversable
public boolean isFocusTraversable()
- Identifies whether or not this component can receive the focus.
A disabled button, for example, would return false.
- Returns:
- true if this component can receive the focus
- Overrides:
- isFocusTraversable in class Component
processFocusEvent
protected void processFocusEvent(FocusEvent e)
- Overrides:
- processFocusEvent in class Component
processComponentKeyEvent
protected void processComponentKeyEvent(KeyEvent e)
- Process any key events that the component itself
recognizes. This will be called after the focus
manager and any interested listeners have been
given a chance to steal away the event. This
method will only be called is the event has not
yet been consumed. This method is called prior
to the keyboard UI logic.
This is implemented to do nothing. Subclasses would
normally override this method if they process some
key events themselves. If the event is processed,
it should be consumed.
processKeyEvent
protected void processKeyEvent(KeyEvent e)
- Override processKeyEvent to process events
- Overrides:
- processKeyEvent in class Component
setToolTipText
public void setToolTipText(String text)
- Registers the text to display in a tool tip.
The text displays when the cursor lingers over the component.
- Parameters:
- text - The string to display. If the text is null,
the tool tip is turned off for this component.
- See Also:
- TOOL_TIP_TEXT_KEY
getToolTipText
public String getToolTipText()
- Return the tooltip string that has been set with setToolTipText()
- Returns:
- the text of the tool tip
- See Also:
- TOOL_TIP_TEXT_KEY
getToolTipText
public String getToolTipText(MouseEvent event)
- Returns the string to be used as the tooltip for event. By default
this returns any string set using setToolTipText(). If a component provides
more extensize API to support differing tooltips at different locations,
this method should be overridden.
getToolTipLocation
public Point getToolTipLocation(MouseEvent event)
- Return the tooltip location in the receiving component coordinate system
If null is returned, Swing will choose a location.
The default implementation returns null.
event is the MouseEvent that caused the ToolTipManager to
show the tooltip.
createToolTip
public JToolTip createToolTip()
- Returns the instance of JToolTip that should be used to display the tooltip.
Components typically would not override this method, but it can be used to
cause different tooltips to be displayed differently.
scrollRectToVisible
public void scrollRectToVisible(Rectangle aRect)
- Forwards the scrollRectToVisible() message to the JComponent's
parent. Components that can service the request, such as a JViewport,
override this method and perform the scrolling.
- See Also:
- JViewport
setAutoscrolls
public void setAutoscrolls(boolean autoscrolls)
- If true this component will automatically scroll its contents when
dragged, if contained in a component that supports scrolling, such as
JViewport
- See Also:
- JViewport, getAutoscrolls
getAutoscrolls
public boolean getAutoscrolls()
- Returns true if this component automatically scrolls its
contents when dragged, (when contained in a component that supports
scrolling, like JViewport
- See Also:
- JViewport, setAutoscrolls
processMouseMotionEvent
protected void processMouseMotionEvent(MouseEvent e)
- Overrides:
- processMouseMotionEvent in class Component
getAccessibleContext
public AccessibleContext getAccessibleContext()
- Get the AccessibleContext associated with this JComponent
- Returns:
- the AccessibleContext of this JComponent
getClientProperty
public final Object getClientProperty(Object key)
- A convenience method for looking up a property value. It is
equivalent to:
getClientProperties().get(key);
- Returns:
- the value of this property or null
- See Also:
- putClientProperty, getClientProperty
putClientProperty
public final void putClientProperty(Object key,
Object value)
- A convenience method for storing up a property value. It is
equivalent to:
getClientProperties().put(key, value);
If value is null this method will remove the property
This method fires PropertyChangeEvents to notify interested
parties of changes to a client property.
- See Also:
- getClientProperty, getClientProperty
isLightweightComponent
public static boolean isLightweightComponent(Component c)
- Returns true if this component is a lightweight, i.e. if it doesn't
have a native window system peer.
This method will migrate to java.awt.Component in the next major JDK release
- Returns:
- true if this component is a lightweight
reshape
public void reshape(int x,
int y,
int w,
int h)
- Moves and resizes this component.
- Overrides:
- reshape in class Component
- See Also:
- setBounds
setBounds
public void setBounds(Rectangle r)
- Moves and resizes this component.
- Overrides:
- setBounds in class Component
- See Also:
- setBounds
getBounds
public Rectangle getBounds(Rectangle rv)
- Store the bounds of this component into "return value" rv and
return rv. If rv is null a new Rectangle is allocated.
This version of getBounds() is useful if the caller
wants to avoid allocating a new Rectangle object on the heap.
- Parameters:
- rv - the return value, modified to the components bounds
- Returns:
- rv
getSize
public Dimension getSize(Dimension rv)
- Store the width/height of this component into "return value" rv
and return rv. If rv is null a new Dimension object is
allocated. This version of getSize() is useful if the
caller wants to avoid allocating a new Dimension object on the heap.
- Parameters:
- rv - the return value, modified to the components size
- Returns:
- rv
getLocation
public Point getLocation(Point rv)
- Store the x,y origin of this component into "return value" rv
and return rv. If rv is null a new Point is allocated.
This version of getLocation() is useful if the
caller wants to avoid allocating a new Point object on the heap.
- Parameters:
- rv - the return value, modified to the components location
- Returns:
- rv
getX
public int getX()
- Return the current x coordinate of the components origin.
This method is preferable to writing component.getBounds().x,
or component.getLocation().x because it doesn't cause any
heap allocations.
This method will migrate to java.awt.Component in the next major JDK release
- Returns:
- the current x coordinate of the components origin.
getY
public int getY()
- Return the current y coordinate of the components origin.
This method is preferable to writing component.getBounds().y,
or component.getLocation().y because it doesn't cause any
heap allocations.
This method will migrate to java.awt.Component in the next major JDK release
- Returns:
- the current y coordinate of the components origin.
getWidth
public int getWidth()
- Return the current width of this component.
This method is preferable to writing component.getBounds().width,
or component.getSize().width because it doesn't cause any
heap allocations.
This method will migrate to java.awt.Component in the next major JDK release
- Returns:
- the current width of this component.
getHeight
public int getHeight()
- Return the current height of this component.
This method is preferable to writing component.getBounds().height,
or component.getSize().height because it doesn't cause any
heap allocations.
This method will migrate to java.awt.Component in the next major JDK release
- Returns:
- the current height of this component.
hasFocus
public boolean hasFocus()
- Returns true if this Component has the keyboard focus.
This method will migrate to java.awt.Component in the next major JDK release
- Returns:
- true if this Component has the keyboard focus.
isOpaque
public boolean isOpaque()
- Returns true if this component is completely opaque.
An opaque component paints every pixel within its
rectangular region. A non-opaque component paints only some of
its pixels, allowing the pixels underneath it to "show through".
A component that does not fully paint its pixels therefore
provides a degree of transparency.
Subclasses that guarantee to always completely paint their contents should
override this method and return true.
This method will migrate to java.awt.Component in the next major JDK release
- Returns:
- true if this component is completely opaque.
- See Also:
- setOpaque
setOpaque
public void setOpaque(boolean isOpaque)
- If true the components background will be filled with the
background color. Otherwise, the background is transparent,
and whatever is underneath will show through.
The default value of this property is false.
This is a JavaBeans bound property.
- See Also:
- isOpaque
computeVisibleRect
public void computeVisibleRect(Rectangle visibleRect)
- Returns the Component's "visible rect rectangle" - the
intersection of the visible rectangles for this component
and all of its ancestors. The return value is stored in
visibleRect
- See Also:
- getVisibleRect
getVisibleRect
public Rectangle getVisibleRect()
- Returns the Component's "visible rectangle" - the
intersection of this components visible rectangle:
new Rectangle(0, 0, getWidth(), getHeight());
and all of its ancestors visible Rectangles.
- Returns:
- the visible rectangle
firePropertyChange
protected void firePropertyChange(String propertyName,
Object oldValue,
Object newValue)
- Support for reporting bound property changes. If oldValue and
newValue are not equal and the PropertyChangeEvent listener list
isn't empty, then fire a PropertyChange event to each listener.
This method has an overloaded method for each primitive type. For
example, here's how to write a bound property set method whose
value is an int:
public void setFoo(int newValue) {
int oldValue = foo;
foo = newValue;
firePropertyChange("foo", oldValue, newValue);
}
This method will migrate to java.awt.Component in the next major JDK release
- Parameters:
- propertyName - The programmatic name of the property that was changed.
- oldValue - The old value of the property.
- newValue - The new value of the property.
- See Also:
- PropertyChangeSupport
firePropertyChange
public void firePropertyChange(String propertyName,
byte oldValue,
byte newValue)
- See Also:
- firePropertyChange
firePropertyChange
public void firePropertyChange(String propertyName,
char oldValue,
char newValue)
- See Also:
- firePropertyChange
firePropertyChange
public void firePropertyChange(String propertyName,
short oldValue,
short newValue)
- See Also:
- firePropertyChange
firePropertyChange
public void firePropertyChange(String propertyName,
int oldValue,
int newValue)
- See Also:
- firePropertyChange
firePropertyChange
public void firePropertyChange(String propertyName,
long oldValue,
long newValue)
- See Also:
- firePropertyChange
firePropertyChange
public void firePropertyChange(String propertyName,
float oldValue,
float newValue)
- See Also:
- firePropertyChange
firePropertyChange
public void firePropertyChange(String propertyName,
double oldValue,
double newValue)
- See Also:
- firePropertyChange
firePropertyChange
public void firePropertyChange(String propertyName,
boolean oldValue,
boolean newValue)
- See Also:
- firePropertyChange
addPropertyChangeListener
public synchronized void addPropertyChangeListener(PropertyChangeListener listener)
- Add a PropertyChangeListener to the listener list.
The listener is registered for all properties.
A PropertyChangeEvent will get fired in response to setting
a bound property, e.g. setFont, setBackground, or setForeground.
Note that if the current component is inheriting its foreground,
background, or font from its container, then no event will be
fired in response to a change in the inherited property.
This method will migrate to java.awt.Component in the next major JDK release
- Parameters:
- listener - The PropertyChangeListener to be added
removePropertyChangeListener
public synchronized void removePropertyChangeListener(PropertyChangeListener listener)
- Remove a PropertyChangeListener from the listener list.
This removes a PropertyChangeListener that was registered
for all properties.
This method will migrate to java.awt.Component in the next major JDK release
- Parameters:
- listener - The PropertyChangeListener to be removed
fireVetoableChange
protected void fireVetoableChange(String propertyName,
Object oldValue,
Object newValue) throws PropertyVetoException
- Support for reporting constrained property changes. This method can be called
when a constrained property has changed and it will send the appropriate
PropertyChangeEvent to any registered VetoableChangeListeners.
This method will migrate to java.awt.Component in the next major JDK release
- Throws: PropertyVetoException
- when the attempt to set the property is vetoed
by the receiver.
addVetoableChangeListener
public synchronized void addVetoableChangeListener(VetoableChangeListener listener)
- Add a VetoableChangeListener to the listener list.
The listener is registered for all properties.
This method will migrate to java.awt.Component in the next major JDK release
- Parameters:
- listener - The VetoableChangeListener to be added
removeVetoableChangeListener
public synchronized void removeVetoableChangeListener(VetoableChangeListener listener)
- Remove a VetoableChangeListener from the listener list.
This removes a VetoableChangeListener that was registered
for all properties.
This method will migrate to java.awt.Component in the next major JDK release
- Parameters:
- listener - The VetoableChangeListener to be removed
getTopLevelAncestor
public Container getTopLevelAncestor()
- Returns the top-level ancestor of this component (either the
containing Window or Applet), or null if this component has not
been added to any container.
- Returns:
- the top-level Container which this component is in.
addAncestorListener
public void addAncestorListener(AncestorListener listener)
- Registers listener so that it will receive AncestorEvents
when it or any of its ancestors move or are made visible / invisible.
Events are also sent when the component or its ancestors are added
or removed from the Component hierarchy
This method will migrate to java.awt.Component in the next major JDK release
- See Also:
- AncestorEvent
removeAncestorListener
public void removeAncestorListener(AncestorListener listener)
- Unregisters listener so that it will no longer receive
AncestorEvents
This method will migrate to java.awt.Component in the next major JDK release
- See Also:
- addAncestorListener
addNotify
public void addNotify()
- Notification to this component that it now has a parent component.
When this method is invoked, the chain of parent components is
set up with KeyboardAction event listeners.
- Overrides:
- addNotify in class Container
- See Also:
- registerKeyboardAction
removeNotify
public void removeNotify()
- Notification to this component that it no longer has a parent component.
When this method is invoked, any KeyboardActions set up in the
the chain of parent components are removed.
- Overrides:
- removeNotify in class Container
- See Also:
- registerKeyboardAction
repaint
public void repaint(long tm,
int x,
int y,
int width,
int height)
- Adds the specified region to the dirty region list if the component
is showing. The component will be repainted after all of the
currently pending events have been dispatched.
- Overrides:
- repaint in class Component
- See Also:
- isShowing, addDirtyRegion
repaint
public void repaint(Rectangle r)
- Adds the specified region to the dirty region list if the component
is showing. The component will be repainted after all of the
currently pending events have been dispatched.
- See Also:
- isShowing, addDirtyRegion
revalidate
public void revalidate()
- Support for deferred automatic layout.
Calls invalidate() and then adds this components validateRoot
to a list of components that need to be validated. Validation
will occur after all currently pending events have been dispatched.
By default only JScrollPane.isValidateRoot() returns true. In other
words after this method is called, the first JScrollPane that
contains this component (if any) will be validated.
- See Also:
- invalidate, validate, isValidateRoot, addInvalidComponent
isValidateRoot
public boolean isValidateRoot()
- If this method returns true, revalidate() calls by descendants of
this component will cause the entire tree beginning with this root
to be validated. Returns false by default. JScrollPane overrides
this method and returns true.
- Returns:
- false
- See Also:
- revalidate, invalidate, validate
isOptimizedDrawingEnabled
public boolean isOptimizedDrawingEnabled()
- Returns true if this component tiles its children, i.e. if
it can guarantee that the children will not overlap. The
repainting system is substantially more efficient in this
common case. JComponent subclasses that can't make this
guarantee, e.g. JLayeredPane, should override this method
to return false.
- Returns:
- true if this components children don't overlap
paintImmediately
public void paintImmediately(int x,
int y,
int w,
int h)
- Paint the specified region in this component and all of its
descendants that overlap the region, immediately.
It's rarely neccessary to call this method. In most cases it's
more efficient to call repaint which defers the actual painting
and can collapse redundant requests into a single paint call.
This method is useful if one needs to update the display while
the current event is being dispatched.
- See Also:
- repaint
paintImmediately
public void paintImmediately(Rectangle r)
- Paint the specified region now.
This method will migrate to java.awt.Component in the next major JDK release
setDoubleBuffered
public void setDoubleBuffered(boolean aFlag)
- Set whether the receiving component should use a buffer to paint.
If set to true, all the drawing from this component will be done
in an offscreen painting buffer. The offscreen painting buffer will
the be copied onto the screen.
Swing's painting system always use a maximum of one double buffer.
If a Component is buffered and one of its ancestor is also buffered,
the ancestor buffer will be used.
isDoubleBuffered
public boolean isDoubleBuffered()
- Return whether the receiving component should use a buffer to paint.
getRootPane
public JRootPane getRootPane()
- Return the receiving component root pane
