Package java.applet

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Class Applet

public  class  java.applet.Applet
    extends  java.awt.Panel  
{
        // Constructors
    public Applet();	

        // Methods
    public void destroy();	
    public AppletContext getAppletContext();	
    public String getAppletInfo();	
    public AudioClip getAudioClip(URL  url);	
    public AudioClip getAudioClip(URL  url, String  name);	
    public URL getCodeBase();	
    public URL getDocumentBase();	
    public Image getImage(URL  url);	
    public Image getImage(URL  url, String  name);	
    public String getParameter(String  name);	
    public String[][] getParameterInfo();	
    public void init();	
    public boolean isActive();	
    public void play(URL  url);	
    public void play(URL  url, String  name);	
    public void resize(Dimension  d);	
    public void resize(int  width, int  height);	
    public final void setStub(AppletStub  stub);	
    public void showStatus(String  msg);	
    public void start();	
    public void stop();	
}

An applet is a small program that is not intended to be run on its own, but 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.

Constructors

Applet

public Applet() 

The default constructor for an applet

Methods

destroy

public void destroy() 

This method is called by the browser or applet viewer to inform thisapplet 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.

See Also: start .

getAppletContext

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.

Return Value:

Returns the applet's context.

getAppletInfo

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.

Return Value:

Returns a string containing information about the author, version and copyright of the applet.

getAudioClip

public AudioClip getAudioClip(URL  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.

Return Value:

Returns the audio clip at the specified URL.

Parameter	Description
url	an absolute URL giving the location of the audio clip

getAudioClip

public AudioClip getAudioClip(URL  url, String  name) 

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.

Return Value:

Returns the audio clip at the specified URL.

Parameter	Description
url	an absolute URL giving the base location of the audio clip
name	the location of the audio clip, relative to the url argument

getCodeBase

public URL getCodeBase() 

Return Value:

Returns the URL of this applet.

See Also: getDocumentBase .

getDocumentBase

public URL getDocumentBase() 

Return Value:

Returns the URL of the document that contains this applet.

See Also: getCodeBase .

getImage

public Image getImage(URL  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.

Return Value:

Returns the image at the specified URL.

Parameter	Description
url	an absolute URL giving the location of the image

getImage

public Image getImage(URL  url, String  name) 

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.

Return Value:

Returns the image at the specified URL.

Parameter	Description
url	an absolute URL giving the base location of the image
name	the location of the image, relative to the url argument

getParameter

public String getParameter(String  name) 

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> 

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

The name argument is case insensitive.

Return Value:

Returns the value of the named parameter.

Parameter	Description
name	a parameter name

getParameterInfo

public String[][] getParameterInfo() 

Returns information about the parameters than can are understood by this applet. An applet should override this method to return an array of 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.

Return Value:

Returns An array describing the parameters this applet looks for.

init

public void init() 

This method is 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.

See Also: stop .

isActive

public boolean isActive() 

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

Return Value:

Returns true if the applet is active; false otherwise.

See Also: start .

play

public void play(URL  url) 

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

Parameter	Description
url	an absolute URL giving the location of the audio clip

play

public void play(URL  url, String  name) 

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

Parameter	Description
url	an absolute URL giving the base location of the audio clip
name	the location of the audio clip, relative to the url argument

resize

public void resize(Dimension  d) 

Requests that this applet be resized.

Parameter	Description
d	An object giving the new width and height

Overrides:

resize in class Component .

resize

public void resize(int  width, int  height) 

Requests that this applet be resized.

Parameter	Description
width	the new requested width for the applet
height	the new requested height for the applet

Overrides:

resize in class Component .

setStub

public final void setStub(AppletStub  stub) 

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

Parameter	Description
stub	The new stub

showStatus

public void showStatus(String  msg) 

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

Parameter	Description
msg	a string to display in the status window

start

public void start() 

This method is 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.

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

See Also: init destroy .

stop

public void stop() 

This method is 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.

See Also: init destroy .