javax.swing
Class JApplet

java.lang.Object
  java.awt.Component
      java.awt.Container
          java.awt.Panel
              java.applet.Applet
                  javax.swing.JApplet

All Implemented Interfaces:

Accessible, ImageObserver, MenuContainer, RootPaneContainer, Serializable

public class JApplet

extends Applet

implements Accessible, RootPaneContainer

An extended version of java.applet.Applet that adds support for the JFC/Swing component architecture. You can find task-oriented documentation about using JApplet in The Java Tutorial, in the section How to Make Applets.

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.

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 JavaBeans^TM has been added to the java.beans package. Please see XMLEncoder.

Nested Class Summary

protected class

JApplet.AccessibleJApplet This class implements accessibility support for the JApplet class.

Nested classes inherited from class java.applet.Applet

Applet.AccessibleApplet

Nested classes inherited from class java.awt.Panel

Panel.AccessibleAWTPanel

Nested classes inherited from class java.awt.Container

Container.AccessibleAWTContainer

Nested classes inherited from class java.awt.Component

Component.AccessibleAWTComponent, Component.BltBufferStrategy, Component.FlipBufferStrategy

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

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

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() Gets 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 String	paramString() Returns a string representation of this JApplet.
void	remove(Component comp) Removes the specified component from this container.
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, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getAlignmentX, getAlignmentY, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getContainerListeners, getFocusTraversalKeys, getFocusTraversalPolicy, getInsets, getLayout, getListeners, getMaximumSize, getMinimumSize, getPreferredSize, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusCycleRoot, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paint, paintComponents, preferredSize, print, printComponents, processContainerEvent, processEvent, remove, removeAll, removeContainerListener, removeNotify, setFocusCycleRoot, setFocusTraversalKeys, setFocusTraversalPolicy, setFont, transferFocusBackward, transferFocusDownCycle, validate, validateTree

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, disable, disableEvents, dispatchEvent, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, getBackground, getBounds, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocation, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, 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, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeysEnabled, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setName, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusUpCycle

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(javax.swing.JRootPane)

rootPaneCheckingEnabled

protected boolean rootPaneCheckingEnabled

See Also:

isRootPaneCheckingEnabled(), setRootPaneCheckingEnabled(boolean)

accessibleContext

protected AccessibleContext accessibleContext

Constructor Detail

JApplet

public JApplet()
        throws HeadlessException

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.

See Also:

GraphicsEnvironment.isHeadless(), JComponent.getDefaultLocale()

Method Detail

createRootPane

protected JRootPane createRootPane()

Called by the constructor methods to create the default rootPane.

update

public void update(Graphics g)

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

Overrides:

update in class Container

Parameters:

g - the specified Graphics window

See Also:

Component.update(Graphics)

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(javax.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.

Overrides:

addImpl in class Container

Parameters:

comp - the component to be added

constraints - an object expressing layout constraints for this component

index - the position in the container's list at which to insert the component, where -1 means append to the end

Throws:

Error - if called with rootPaneChecking true

See Also:

setRootPaneCheckingEnabled(boolean)

remove

public void remove(Component comp)

Removes the specified component from this container.

Overrides:

remove in class Container

Parameters:

comp - the component to be removed

See Also:

Container.add(java.awt.Component)

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:

 thisComponent.getContentPane().setLayout(new GridLayout(1, 2))
 

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

Overrides:

setLayout in class Container

Parameters:

manager - the specified layout manager

Throws:

Error - if called with rootPaneChecking true

See Also:

setRootPaneCheckingEnabled(boolean)

getRootPane

public JRootPane getRootPane()

Returns the rootPane object for this applet.

Specified by:

getRootPane in interface RootPaneContainer

Returns:

this components single JRootPane child.

See Also:

setRootPane(javax.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

Returns:

the value of the contentPane property.

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

Returns:

the value of the layeredPane property.

Throws:

IllegalComponentStateException - (a runtime exception) if the layered pane parameter is null

See Also:

setLayeredPane(javax.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(javax.swing.JLayeredPane)

getGlassPane

public Component getGlassPane()

Returns the glassPane object for this applet.

Specified by:

getGlassPane in interface RootPaneContainer

Returns:

the value of the glassPane property.

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)

paramString

protected String paramString()

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.

Overrides:

paramString in class Container

Returns:

a string representation of this JApplet.

getAccessibleContext

public AccessibleContext getAccessibleContext()

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.

Specified by:

getAccessibleContext in interface Accessible

Overrides:

getAccessibleContext in class Applet

Returns:

an AccessibleJApplet that serves as the AccessibleContext of this JApplet