Class com.sun.java.swing.JApplet

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Class com.sun.java.swing.JApplet

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.Container
              |
              +--java.awt.Panel
                    |
                    +--java.applet.Applet
                          |
                          +--com.sun.java.swing.JApplet

public class JApplet
extends Applet
implements Accessible, RootPaneContainer

An extended version of java.applet.Applet that adds support for interposing input and painting behavior in front of the applets children (see glassPane), support for special children that are managed by a LayeredPane (see rootPane) and for Swing MenuBars.

The JApplet class is slightly incompatible with java.applet.Applet. JApplet contains a JRootPane as it's only child. The contentPane should be the parent of any children of the JApplet. This is different than java.applet.Applet, e.g. to add a child to an an java.applet.Applet you'd write:

       applet.add(child);

However using JApplet you need to add the child to the JApplet's contentPane instead:

       applet.getContentPane().add(child);

The same is true for setting LayoutManagers, removing components, listing children, etc. All these methods should normally be sent to the contentPane() instead of the JApplet itself. The contentPane() will always be non-null. Attempting to set it to null will cause the JApplet to throw an exception. The default contentPane() will have a BorderLayout manager set on it.

Please see the JRootPane documentation for a complete description of the contentPane, glassPane, and layeredPane properties.

For the keyboard keys used by this component in the standard Look and Feel (L&F) renditions, see the JApplet key assignments.

Both Netscape Communicator and Internet Explorer 4.0 unconditionally print an error message to the Java console when an applet attempts to access the AWT system event queue. Swing applets do this once, to check if access is permitted. To prevent the warning message in a production applet one can set a client property called "defeatSystemEventQueueCheck" on the JApplets RootPane to any non null value, e.g:

 JRootPane rp = myJApplet.getRootPane();
 rp.putClientProperty("defeatSystemEventQueueCheck", Boolean.TRUE);

We hope that future versions of the browsers will not have this limitation and we'll be able to retire this hack.

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:: Serialized Form

Inner Class Summary
protected	JApplet.AccessibleJApplet

Field Summary
protected AccessibleContext	accessibleContext
protected JRootPane	rootPane
protected boolean	rootPaneCheckingEnabled

Fields inherited from class java.awt.Component
BOTTOM_ALIGNMENT , CENTER_ALIGNMENT , LEFT_ALIGNMENT , RIGHT_ALIGNMENT , TOP_ALIGNMENT

Constructor Summary
JApplet() Creates a swing applet instance.

Method Summary
protected void	addImpl(Component comp, Object constraints, int index) By default, children may not be added directly to a this component, they must be added to its contentPane instead.
protected JRootPane	createRootPane() Called by the constructor methods to create the default rootPane.
AccessibleContext	getAccessibleContext() Get the AccessibleContext associated with this JApplet
Container	getContentPane() Returns the contentPane object for this applet.
Component	getGlassPane() Returns the glassPane object for this applet.
JMenuBar	getJMenuBar() Returns the menubar set on this applet.
JLayeredPane	getLayeredPane() Returns the layeredPane object for this applet.
JRootPane	getRootPane() Returns the rootPane object for this applet.
protected boolean	isRootPaneCheckingEnabled()
protected void	processKeyEvent(KeyEvent e)
void	setContentPane(Container contentPane) Sets the contentPane property.
void	setGlassPane(Component glassPane) Sets the glassPane property.
void	setJMenuBar(JMenuBar menuBar) Sets the menubar for this applet.
void	setLayeredPane(JLayeredPane layeredPane) Sets the layeredPane property.
void	setLayout(LayoutManager manager) By default the layout of this component may not be set, the layout of its contentPane should be set instead.
protected void	setRootPane(JRootPane root) Sets the rootPane property.
protected void	setRootPaneCheckingEnabled(boolean enabled) If true then calls to add() and setLayout() will cause an exception to be thrown.
void	update(Graphics g) Just calls `paint(g)`.

Methods inherited from class java.applet.Applet
destroy , getAppletContext , getAppletInfo , getAudioClip , getAudioClip , getCodeBase , getDocumentBase , getImage , getImage , getLocale , getParameter , getParameterInfo , init , isActive , newAudioClip , play , play , resize , resize , setStub , showStatus , start , stop

Methods inherited from class java.awt.Panel
addNotify

Methods inherited from class java.awt.Container

add , add , add , add , add , addContainerListener , countComponents , deliverEvent , doLayout , findComponentAt , findComponentAt , getAlignmentX , getAlignmentY , getComponent , getComponentAt , getComponentAt , getComponentCount , getComponents , getInsets , getLayout , getMaximumSize , getMinimumSize , getPreferredSize , insets , invalidate , isAncestorOf , layout , list , list , locate , minimumSize , paint , paintComponents , paramString , preferredSize , print , printComponents , processContainerEvent , processEvent , remove , remove , removeAll , removeContainerListener , removeNotify , validate , validateTree

Methods inherited from class java.awt.Component

action , add , addComponentListener , addFocusListener , addInputMethodListener , addKeyListener , addMouseListener , addMouseMotionListener , addPropertyChangeListener , addPropertyChangeListener , bounds , checkImage , checkImage , coalesceEvents , contains , contains , createImage , createImage , disable , disableEvents , dispatchEvent , enable , enable , enableEvents , enableInputMethods , firePropertyChange , getBackground , getBounds , getBounds , getColorModel , getComponentOrientation , getCursor , getDropTarget , getFont , getFontMetrics , getForeground , getGraphics , getHeight , getInputContext , getInputMethodRequests , getLocation , getLocation , getLocationOnScreen , getName , getParent , getPeer , getSize , getSize , getToolkit , getTreeLock , getWidth , getX , getY , gotFocus , handleEvent , hasFocus , hide , imageUpdate , inside , isDisplayable , isDoubleBuffered , isEnabled , isFocusTraversable , isLightweight , isOpaque , isShowing , isValid , isVisible , keyDown , keyUp , list , list , list , location , lostFocus , mouseDown , mouseDrag , mouseEnter , mouseExit , mouseMove , mouseUp , move , nextFocus , paintAll , postEvent , prepareImage , prepareImage , printAll , processComponentEvent , processFocusEvent , processInputMethodEvent , processMouseEvent , processMouseMotionEvent , remove , removeComponentListener , removeFocusListener , removeInputMethodListener , removeKeyListener , removeMouseListener , removeMouseMotionListener , removePropertyChangeListener , removePropertyChangeListener , repaint , repaint , repaint , repaint , requestFocus , reshape , setBackground , setBounds , setBounds , setComponentOrientation , setCursor , setDropTarget , setEnabled , setFont , setForeground , setLocale , setLocation , setLocation , setName , setSize , setSize , setVisible , show , show , size , toString , transferFocus

Methods inherited from class java.lang.Object
clone , equals , finalize , getClass , hashCode , notify , notifyAll , wait , wait , wait

Field Detail

rootPane

protected JRootPane rootPane

See Also:: getRootPane(), setRootPane(com.sun.java.swing.JRootPane)

rootPaneCheckingEnabled

protected boolean rootPaneCheckingEnabled

See Also:: isRootPaneCheckingEnabled(), setRootPaneCheckingEnabled(boolean)

accessibleContext

protected AccessibleContext accessibleContext

Constructor Detail

JApplet

public JApplet()

Creates a swing applet instance.

Method Detail

createRootPane

protected JRootPane createRootPane()

Called by the constructor methods to create the default rootPane.

processKeyEvent

protected void processKeyEvent(KeyEvent e)

Overrides:: processKeyEvent in class Component

update

public void update(Graphics g)

Just calls paint(g). This method was overridden to prevent an unneccessary call to clear the background.

Overrides:: update in class Container

setJMenuBar

public void setJMenuBar(JMenuBar menuBar)

Sets the menubar for this applet.

Parameters:: menubar - the menubar being placed in the applet
See Also:: getJMenuBar()

getJMenuBar

public JMenuBar getJMenuBar()

Returns the menubar set on this applet.

See Also:: setJMenuBar(com.sun.java.swing.JMenuBar)

isRootPaneCheckingEnabled

protected boolean isRootPaneCheckingEnabled()

Returns:: true if add and setLayout should be checked
See Also:: addImpl(java.awt.Component, java.lang.Object, int), setLayout(java.awt.LayoutManager), setRootPaneCheckingEnabled(boolean)

setRootPaneCheckingEnabled

protected void setRootPaneCheckingEnabled(boolean enabled)

If true then calls to add() and setLayout() will cause an exception to be thrown.

See Also:: addImpl(java.awt.Component, java.lang.Object, int), setLayout(java.awt.LayoutManager), isRootPaneCheckingEnabled()

addImpl

protected void addImpl(Component comp,
                       Object constraints,
                       int index)

By default, children may not be added directly to a this component, they must be added to its contentPane instead. For example:

 thiComponent.getContentPane().add(child)

An attempt to add to directly to this component will cause an runtime exception to be thrown. Subclasses can disable this behavior.

Throws:: Error - if called with rootPaneChecking true
Overrides:: addImpl in class Container
See Also:: setRootPaneCheckingEnabled(boolean)

setLayout

public void setLayout(LayoutManager manager)

By default the layout of this component may not be set, the layout of its contentPane should be set instead. For example:

 thiComponent.getContentPane().setLayout(new BorderLayout())

An attempt to set the layout of this component will cause an runtime exception to be thrown. Subclasses can disable this behavior.

Throws:: Error - if called with rootPaneChecking true
Overrides:: setLayout in class Container
See Also:: setRootPaneCheckingEnabled(boolean)

getRootPane

public JRootPane getRootPane()

Returns the rootPane object for this applet.

Specified by:: getRootPane in interface RootPaneContainer
See Also:: setRootPane(com.sun.java.swing.JRootPane), RootPaneContainer.getRootPane()

setRootPane

protected void setRootPane(JRootPane root)

Sets the rootPane property. This method is called by the constructor.

Parameters:: root - the rootPane object for this applet
See Also:: getRootPane()

getContentPane

public Container getContentPane()

Returns the contentPane object for this applet.

Specified by:: getContentPane in interface RootPaneContainer
See Also:: setContentPane(java.awt.Container), RootPaneContainer.getContentPane()

setContentPane

public void setContentPane(Container contentPane)

Sets the contentPane property. This method is called by the constructor.

Specified by:: setContentPane in interface RootPaneContainer
Parameters:: contentPane - the contentPane object for this applet
Throws:: IllegalComponentStateException - (a runtime exception) if the content pane parameter is null
See Also:: getContentPane(), RootPaneContainer.setContentPane(java.awt.Container)

getLayeredPane

public JLayeredPane getLayeredPane()

Returns the layeredPane object for this applet.

Specified by:: getLayeredPane in interface RootPaneContainer
Throws:: IllegalComponentStateException - (a runtime exception) if the layered pane parameter is null
See Also:: setLayeredPane(com.sun.java.swing.JLayeredPane), RootPaneContainer.getLayeredPane()

setLayeredPane

public void setLayeredPane(JLayeredPane layeredPane)

Sets the layeredPane property. This method is called by the constructor.

Specified by:: setLayeredPane in interface RootPaneContainer
Parameters:: layeredPane - the layeredPane object for this applet
See Also:: getLayeredPane(), RootPaneContainer.setLayeredPane(com.sun.java.swing.JLayeredPane)

getGlassPane

public Component getGlassPane()

Returns the glassPane object for this applet.

Specified by:: getGlassPane in interface RootPaneContainer
See Also:: setGlassPane(java.awt.Component), RootPaneContainer.getGlassPane()

setGlassPane

public void setGlassPane(Component glassPane)

Sets the glassPane property. This method is called by the constructor.

Specified by:: setGlassPane in interface RootPaneContainer
Parameters:: glassPane - the glassPane object for this applet
See Also:: getGlassPane(), RootPaneContainer.setGlassPane(java.awt.Component)

getAccessibleContext

public AccessibleContext getAccessibleContext()

Get the AccessibleContext associated with this JApplet

Specified by:: getAccessibleContext in interface Accessible
Returns:: the AccessibleContext of this JApplet