public class Applet
extends Panel

An applet is a small program that is intended not to be run on its own, but rather to be embedded inside another application.

The Applet class must be the superclass of any applet that is to be embedded in a Web page or viewed by the Java Applet Viewer. The Applet class provides a standard interface between applets and their environment.

public Applet()

Constructs a new Applet.

Note: Many methods in java.applet.Applet may be invoked by the applet only after the applet is fully constructed; applet should avoid calling methods in java.applet.Applet in the constructor.

HeadlessException: if GraphicsEnvironment.isHeadless() returns true.

public void destroy()

Called by the browser or applet viewer to inform this applet that it is being reclaimed and that it should destroy any resources that it has allocated. The stop method will always be called before destroy.

A subclass of Applet should override this method if it has any operation that it wants to perform before it is destroyed. For example, an applet with threads would use the init method to create the threads and the destroy method to kill them.

The implementation of this method provided by the Applet class does nothing.

public AccessibleContext getAccessibleContext()

Gets the AccessibleContext associated with this Applet. For applets, the AccessibleContext takes the form of an AccessibleApplet. A new AccessibleApplet instance is created if necessary.

public AppletContext getAppletContext()

Determines this applet's context, which allows the applet to query and affect the environment in which it runs.

This environment of an applet represents the document that contains the applet.

public String getAppletInfo()

Returns information about this applet. An applet should override this method to return a String containing information about the author, version, and copyright of the applet.

The implementation of this method provided by the Applet class returns null.

public AudioClip getAudioClip(URL)

Returns the AudioClip object specified by the URL argument.

This method always returns immediately, whether or not the audio clip exists. When this applet attempts to play the audio clip, the data will be loaded.

URL url: an absolute URL giving the location of the audio clip.

public AudioClip getAudioClip(URL, String)

Returns the AudioClip object specified by the URL and name arguments.

This method always returns immediately, whether or not the audio clip exists. When this applet attempts to play the audio clip, the data will be loaded.

URL url: an absolute URL giving the base location of the audio clip.

String name: the location of the audio clip, relative to the url argument.

public URL getCodeBase()

Gets the base URL. This is the URL of the directory which contains this applet.

public URL getDocumentBase()

Gets the URL of the document in which this applet is embedded. For example, suppose an applet is contained within the document:

    http://java.sun.com/products/jdk/1.2/index.html
 

    http://java.sun.com/products/jdk/1.2/index.html
 

public Image getImage(URL)

Returns an Image object that can then be painted on the screen. The url that is passed as an argument must specify an absolute URL.

This method always returns immediately, whether or not the image exists. When this applet attempts to draw the image on the screen, the data will be loaded. The graphics primitives that draw the image will incrementally paint on the screen.

URL url: an absolute URL giving the location of the image.

public Image getImage(URL, String)

Returns an Image object that can then be painted on the screen. The url argument must specify an absolute URL. The name argument is a specifier that is relative to the url argument.

This method always returns immediately, whether or not the image exists. When this applet attempts to draw the image on the screen, the data will be loaded. The graphics primitives that draw the image will incrementally paint on the screen.

URL url: an absolute URL giving the base location of the image.

String name: the location of the image, relative to the url argument.

public Locale getLocale()

Gets the locale of the applet. It allows the applet to maintain its own locale separated from the locale of the browser or appletviewer.

public String getParameter(String)

Returns the value of the named parameter in the HTML tag. For example, if this applet is specified as

 <applet code="Clock" width=50 height=50>
 <param name=Color value="blue">
 </applet>
 

then a call to getParameter("Color") returns the value "blue".

The name argument is case insensitive.

String name: a parameter name.

public String getParameterInfo()

Returns information about the parameters that are understood by this applet. An applet should override this method to return an array of Strings describing these parameters.

Each element of the array should be a set of three Strings containing the name, the type, and a description. For example:

 String pinfo[][] = {
   {"fps",    "1-10",    "frames per second"},
   {"repeat", "boolean", "repeat image loop"},
   {"imgs",   "url",     "images directory"}
 };
 

The implementation of this method provided by the Applet class returns null.

public void init()

Called by the browser or applet viewer to inform this applet that it has been loaded into the system. It is always called before the first time that the start method is called.

A subclass of Applet should override this method if it has initialization to perform. For example, an applet with threads would use the init method to create the threads and the destroy method to kill them.

The implementation of this method provided by the Applet class does nothing.

public boolean isActive()

Determines if this applet is active. An applet is marked active just before its start method is called. It becomes inactive just before its stop method is called.

public static final AudioClip newAudioClip(URL)

Get an audio clip from the given URL.

URL url: points to the audio clip

public void play(URL)

Plays the audio clip at the specified absolute URL. Nothing happens if the audio clip cannot be found.

URL url: an absolute URL giving the location of the audio clip.

public void play(URL, String)

Plays the audio clip given the URL and a specifier that is relative to it. Nothing happens if the audio clip cannot be found.

URL url: an absolute URL giving the base location of the audio clip.

String name: the location of the audio clip, relative to the url argument.

public void resize(Dimension)

Requests that this applet be resized.

Dimension d: an object giving the new width and height.

public void resize(int, int)

Requests that this applet be resized.

int width: the new requested width for the applet.

int height: the new requested height for the applet.

public final void setStub(AppletStub)

Sets this applet's stub. This is done automatically by the system.

If there is a security manager, its checkPermission method is called with the AWTPermission("setAppletStub") permission if a stub has already been set.

AppletStub stub: the new stub.

SecurityException: if the caller cannot set the stub

public void showStatus(String)

Requests that the argument string be displayed in the "status window". Many browsers and applet viewers provide such a window, where the application can inform users of its current state.

String msg: a string to display in the status window.

public void start()

Called by the browser or applet viewer to inform this applet that it should start its execution. It is called after the init method and each time the applet is revisited in a Web page.

A subclass of Applet should override this method if it has any operation that it wants to perform each time the Web page containing it is visited. For example, an applet with animation might want to use the start method to resume animation, and the stop method to suspend the animation.

Note: some methods, such as getLocationOnScreen, can only provide meaningful results if the applet is showing. Because isShowing returns false when the applet's start is first called, methods requiring isShowing to return true should be called from a ComponentListener.

The implementation of this method provided by the Applet class does nothing.

public void stop()

Called by the browser or applet viewer to inform this applet that it should stop its execution. It is called when the Web page that contains this applet has been replaced by another page, and also just before the applet is to be destroyed.

A subclass of Applet should override this method if it has any operation that it wants to perform each time the Web page containing it is no longer visible. For example, an applet with animation might want to use the start method to resume animation, and the stop method to suspend the animation.

The implementation of this method provided by the Applet class does nothing.