Class JApplet

All Implemented Interfaces:
ImageObserver, MenuContainer, Serializable, Accessible, RootPaneContainer 

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 its only child. The contentPane should be the parent of any children of the JApplet. As a convenience, the add, remove, and setLayout methods of this class are overridden, so that they delegate calls to the corresponding methods of the ContentPane. For example, you can add a child component to an applet as follows: 

applet.add(child);
And the child will be added to the contentPane. 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. Refer to RootPaneContainer for details on adding, removing and setting the LayoutManager of a JApplet.

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

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

See Also:
RootPaneContainer

Nested Classes

Modifier and Type Class and Description
protected class  JApplet.AccessibleJApplet

This class implements accessibility support for the JApplet class.

Nested classes/interfaces inherited from class java.applet.Applet

Applet.AccessibleApplet

Nested classes/interfaces inherited from class java.awt.Panel

Panel.AccessibleAWTPanel

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

Fields

Modifier and Type Field and Description
protected AccessibleContext accessibleContext
protected JRootPane rootPane
protected boolean rootPaneCheckingEnabled

If true then calls to add and setLayout will be forwarded to the contentPane.

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

Constructors

Constructor and Description
JApplet()

Creates a swing applet instance.

Methods

Modifier and Type Method and Description
protected void addImpl(Component comp, Object constraints, int index)

Adds the specified child Component.
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.
Graphics getGraphics()

Creates a graphics context for this component.
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.
TransferHandler getTransferHandler()

Gets the transferHandler property.
protected boolean isRootPaneCheckingEnabled()

Returns whether calls to add and setLayout are forwarded to the contentPane.
protected String paramString()

Returns a string representation of this JApplet.
void remove(Component comp)

Removes the specified component from the container.
void repaint(long time, int x, int y, int width, int height)

Repaints the specified rectangle of this component within time milliseconds.
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)

Sets the LayoutManager.
protected void setRootPane(JRootPane root)

Sets the rootPane property.
protected void setRootPaneCheckingEnabled(boolean enabled)

Sets whether calls to add and setLayout are forwarded to the contentPane.
void setTransferHandler(TransferHandler newHandler)

Sets the transferHandler property, which is a mechanism to support transfer of data into this component.
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, isValidateRoot, 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, getComponentZOrder, getContainerListeners, getFocusTraversalKeys, getFocusTraversalPolicy, getInsets, getLayout, getListeners, getMaximumSize, getMinimumSize, getMousePosition, getPreferredSize, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusCycleRoot, isFocusTraversalPolicyProvider, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paint, paintComponents, preferredSize, print, printComponents, processContainerEvent, processEvent, remove, removeAll, removeContainerListener, removeNotify, setComponentZOrder, setFocusCycleRoot, setFocusTraversalKeys, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setFont, 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, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getBackground, getBaseline, getBaselineResizeBehavior, getBounds, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocation, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMousePosition, 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, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, 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, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, revalidate, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeysEnabled, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Fields

rootPane

protected JRootPane rootPane
See Also:
getRootPane(), setRootPane(javax.swing.JRootPane)

rootPaneCheckingEnabled

protected boolean rootPaneCheckingEnabled

If true then calls to add and setLayout will be forwarded to the contentPane. This is initially false, but is set to true when the JApplet is constructed.

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

accessibleContext

protected AccessibleContext accessibleContext

Constructors

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()

Methods

createRootPane

protected JRootPane createRootPane()

Called by the constructor methods to create the default rootPane.

setTransferHandler

public void setTransferHandler(TransferHandler newHandler)

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

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

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

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

Parameters:
newHandler - the new TransferHandler
Since:
1.6
See Also:
TransferHandler, getTransferHandler(), Component.setDropTarget(java.awt.dnd.DropTarget)

getTransferHandler

public TransferHandler getTransferHandler()

Gets the transferHandler property.

Returns:
the value of the transferHandler property
Since:
1.6
See Also:
TransferHandler, setTransferHandler(javax.swing.TransferHandler)

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

Returns:
true if add and setLayout are forwarded; false otherwise
See Also:
addImpl(java.awt.Component, java.lang.Object, int), setLayout(java.awt.LayoutManager), setRootPaneCheckingEnabled(boolean), RootPaneContainer

setRootPaneCheckingEnabled

protected void setRootPaneCheckingEnabled(boolean enabled)

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

Parameters:
enabled - true if add and setLayout are forwarded, false if they should operate directly on the JApplet.
See Also:
addImpl(java.awt.Component, java.lang.Object, int), setLayout(java.awt.LayoutManager), isRootPaneCheckingEnabled(), RootPaneContainer

addImpl

protected void addImpl(Component comp,
                       Object constraints,
                       int 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 RootPaneContainer for details.

Overrides:
addImpl in class Container
Parameters:
comp - the component to be enhanced
constraints - the constraints to be respected
index - the index
Throws:
IllegalArgumentException - if index is invalid
IllegalArgumentException - if adding the container's parent to itself
IllegalArgumentException - if adding a window to a container
See Also:
setRootPaneCheckingEnabled(boolean), RootPaneContainer

remove

public void remove(Component 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.

Overrides:
remove in class Container
Parameters:
comp - the component to be removed
Throws:
NullPointerException - if comp is null
See Also:
Container.add(java.awt.Component), RootPaneContainer

setLayout

public void setLayout(LayoutManager manager)

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

Overrides:
setLayout in class Container
Parameters:
manager - the LayoutManager
See Also:
setRootPaneCheckingEnabled(boolean), RootPaneContainer

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)

getGraphics

public Graphics getGraphics()

Creates a graphics context for this component. This method will return null if this component is currently not displayable.

Overrides:
getGraphics in class Component
Returns:
a graphics context for this component, or null if it has none
Since:
1.6
See Also:
Component.paint(java.awt.Graphics)

repaint

public void repaint(long time,
                    int x,
                    int y,
                    int width,
                    int height)

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

Overrides:
repaint in class Component
Parameters:
time - maximum time in milliseconds before update
x - the x coordinate
y - the y coordinate
width - the width
height - the height
Since:
1.6
See Also:
RepaintManager

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

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https://docs.oracle.com/javase/8/docs/api/javax/swing/JApplet.html