Also see:

getRootPane
setRootPane

Also see:

isRootPaneCheckingEnabled
setRootPaneCheckingEnabled
javax.swing.RootPaneContainer

 public JApplet() throws HeadlessException 
{
                                      
        super();
        // Check the timerQ and restart if necessary.
        TimerQueue q = TimerQueue.sharedInstance();
        if(q != null) {
            synchronized(q) {
                if(!q.running)
                    q.start();
            }
        }
        /* Workaround for bug 4155072.  The shared double buffer image
         * may hang on to a reference to this applet; unfortunately
         * Image.getGraphics() will continue to call JApplet.getForeground()
         * and getBackground() even after this applet has been destroyed.
         * So we ensure that these properties are non-null here.
         */
        setForeground(Color.black);
        setBackground(Color.white);
        setLocale( JComponent.getDefaultLocale() );
        setLayout(new BorderLayout());
        setRootPane(createRootPane());
        setRootPaneCheckingEnabled(true);
        setFocusTraversalPolicyProvider(true);
        sun.awt.SunToolkit.checkAndSetPolicy(this, true);
        enableEvents(AWTEvent.KEY_EVENT_MASK);
}

Creates a swing applet instance.

This constructor sets the component's locale property to the value returned by JComponent.getDefaultLocale.

Throws:

HeadlessException - if GraphicsEnvironment.isHeadless() returns true.

Also see:

java.awt.GraphicsEnvironment#isHeadless
JComponent#getDefaultLocale
exception: HeadlessException - if GraphicsEnvironment.isHeadless() returns true.

 protected  void addImpl(Component comp,
    Object constraints,
    int index) 
{
        if(isRootPaneCheckingEnabled()) {
            getContentPane().add(comp, constraints, index);
        }
        else {
            super.addImpl(comp, constraints, index);
        }
}

Adds the specified child Component. This method is overridden to conditionally forward calls to the contentPane. By default, children are added to the contentPane instead of the frame, refer to javax.swing.RootPaneContainer for details.

 protected JRootPane createRootPane() 
{
        JRootPane rp = new JRootPane();
        // NOTE: this uses setOpaque vs LookAndFeel.installProperty as there
        // is NO reason for the RootPane not to be opaque. For painting to
        // work the contentPane must be opaque, therefor the RootPane can
        // also be opaque.
        rp.setOpaque(true);
        return rp;
}

Called by the constructor methods to create the default rootPane.

 public AccessibleContext getAccessibleContext() 
{
                                                     
        if (accessibleContext == null) {
            accessibleContext = new AccessibleJApplet();
        }
        return accessibleContext;
}

Gets the AccessibleContext associated with this JApplet. For JApplets, the AccessibleContext takes the form of an AccessibleJApplet. A new AccessibleJApplet instance is created if necessary.

 public Container getContentPane() 
{
        return getRootPane().getContentPane();
}

Returns the contentPane object for this applet.

 public Component getGlassPane() 
{
        return getRootPane().getGlassPane();
}

Returns the glassPane object for this applet.

 public Graphics getGraphics() 
{
        JComponent.getGraphicsInvoked(this);
        return super.getGraphics();
}

{@inheritDoc}

 public JMenuBar getJMenuBar() 
{
        return getRootPane().getMenuBar();
}

Returns the menubar set on this applet.

 public JLayeredPane getLayeredPane() 
{
        return getRootPane().getLayeredPane();
}

Returns the layeredPane object for this applet.

 public JRootPane getRootPane() 
{
        return rootPane;
}

Returns the rootPane object for this applet.

 public TransferHandler getTransferHandler() 
{
        return transferHandler;
}

Gets the transferHandler property.

 protected boolean isRootPaneCheckingEnabled() 
{
        return rootPaneCheckingEnabled;
}

Returns whether calls to add and setLayout are forwarded to the contentPane.

 protected String paramString() 
{
        String rootPaneString = (rootPane != null ?
                                 rootPane.toString() : "");
        String rootPaneCheckingEnabledString = (rootPaneCheckingEnabled ?
                                                "true" : "false");
        return super.paramString() +
        ",rootPane=" + rootPaneString +
        ",rootPaneCheckingEnabled=" + rootPaneCheckingEnabledString;
}

Returns a string representation of this JApplet. 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.

 public  void remove(Component comp) 
{
        if (comp == rootPane) {
            super.remove(comp);
        } else {
            getContentPane().remove(comp);
        }
}

Removes the specified component from the container. If comp is not the rootPane, this will forward the call to the contentPane. This will do nothing if comp is not a child of the JFrame or contentPane.

 public  void repaint(long time,
    int x,
    int y,
    int width,
    int height) 
{
        if (RepaintManager.HANDLE_TOP_LEVEL_PAINT) {
            RepaintManager.currentManager(this).addDirtyRegion(
                              this, x, y, width, height);
        }
        else {
            super.repaint(time, x, y, width, height);
        }
}

Repaints the specified rectangle of this component within time milliseconds. Refer to RepaintManager for details on how the repaint is handled.

 public  void setContentPane(Container contentPane) 
{
        getRootPane().setContentPane(contentPane);
}

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

 public  void setGlassPane(Component glassPane) 
{
        getRootPane().setGlassPane(glassPane);
}

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

 public  void setJMenuBar(JMenuBar menuBar) 
{
        getRootPane().setMenuBar(menuBar);
}

Sets the menubar for this applet.

 public  void setLayeredPane(JLayeredPane layeredPane) 
{
        getRootPane().setLayeredPane(layeredPane);
}

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

 public  void setLayout(LayoutManager manager) 
{
        if(isRootPaneCheckingEnabled()) {
            getContentPane().setLayout(manager);
        }
        else {
            super.setLayout(manager);
        }
}

Sets the LayoutManager. Overridden to conditionally forward the call to the contentPane. Refer to javax.swing.RootPaneContainer for more information.

 protected  void setRootPane(JRootPane root) 
{
        if(rootPane != null) {
            remove(rootPane);
        }
        rootPane = root;
        if(rootPane != null) {
            boolean checkingEnabled = isRootPaneCheckingEnabled();
            try {
                setRootPaneCheckingEnabled(false);
                add(rootPane, BorderLayout.CENTER);
            }
            finally {
                setRootPaneCheckingEnabled(checkingEnabled);
            }
        }
}

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

 protected  void setRootPaneCheckingEnabled(boolean enabled) 
{
        rootPaneCheckingEnabled = enabled;
}

Sets whether calls to add and setLayout are forwarded to the contentPane.

 public  void setTransferHandler(TransferHandler newHandler) 
{
        TransferHandler oldHandler = transferHandler;
        transferHandler = newHandler;
        SwingUtilities.installSwingDropTargetAsNecessary(this, transferHandler);
        firePropertyChange("transferHandler", oldHandler, newHandler);
}

Sets the {@code transferHandler} property, which is a mechanism to support transfer of data into this component. Use {@code null} if the component does not support data transfer operations.

If the system property {@code suppressSwingDropSupport} is {@code false} (the default) and the current drop target on this component is either {@code null} or not a user-set drop target, this method will change the drop target as follows: If {@code newHandler} is {@code null} it will clear the drop target. If not {@code null} it will install a new {@code DropTarget}.

Note: When used with {@code JApplet}, {@code TransferHandler} only provides data import capability, as the data export related methods are currently typed to {@code JComponent}.

Please see How to Use Drag and Drop and Data Transfer, a section in The Java Tutorial, for more information.

 public  void update(Graphics g) 
{
        paint(g);
}

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