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Class java.applet.Applet
java.lang.Object
|
+----java.awt.Component
|
+----java.awt.Container
|
+----java.awt.Panel
|
+----java.applet.Applet
- 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.
- Applet()
- 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.
- getAppletContext()
- Determines this applet's context, which allows the applet to query and affect the environment in which it runs.
- getAppletInfo()
- Returns information about this applet.
- getAudioClip(URL)
- Returns the
AudioClip
object specified by the URL
argument. - getAudioClip(URL, String)
- Returns the
AudioClip
object specified by the URL
and name
arguments. - getCodeBase()
- Gets the base URL.
- getDocumentBase()
- Gets the document URL.
- getImage(URL)
- Returns an
Image
object that can then be painted on the screen. - getImage(URL, String)
- Returns an
Image
object that can then be painted on the screen. - getLocale()
- Gets the Locale for the applet, if it has been set.
- getParameter(String)
- Returns the value of the named parameter in the HTML tag.
- getParameterInfo()
- Returns information about the parameters than are understood by this applet.
- init()
- Called by the browser or applet viewer to inform this applet that it has been loaded into the system.
- isActive()
- Determines if this applet is active.
- play(URL)
- Plays the audio clip at the specified absolute URL.
- play(URL, String)
- Plays the audio clip given the URL and a specifier that is relative to it.
- resize(Dimension)
- Requests that this applet be resized.
- resize(int, int)
- Requests that this applet be resized.
- setStub(AppletStub)
- Sets this applet's stub.
- showStatus(String)
- Requests that the argument string be displayed in the "status window".
- start()
- Called by the browser or applet viewer to inform this applet that it should start its execution.
- stop()
- Called by the browser or applet viewer to inform this applet that it should stop its execution.
Applet
public Applet()
setStub
public final void setStub(AppletStub stub)
- Sets this applet's stub. This is done automatically by the system.
- Parameters:
- stub - the new stub.
isActive
public boolean isActive()
- Determines if this applet is active. An applet is marked active just before its
start
method is called. It becomes inactive immediately after its stop
method is called. - Returns:
true
if the applet is active; false
otherwise. - See Also:
- start, stop
getDocumentBase
public URL getDocumentBase()
- Gets the document URL. This is the URL of the document in which the applet is embedded.
- Returns:
- the
URL
of the document that contains this applet. - See Also:
- getCodeBase
getCodeBase
public URL getCodeBase()
- Gets the base URL. This is the URL of the applet itself.
- Returns:
- the
URL
of this applet. - See Also:
- getDocumentBase
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>
then a call to getParameter("Color")
returns the value "blue"
.
The name
argument is case insensitive.
- Parameters:
- name - a parameter name.
- Returns:
- the value of the named parameter.
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.
- Returns:
- the applet's context.
resize
public void resize(int width,
int height)
- Requests that this applet be resized.
- Parameters:
- width - the new requested width for the applet.
- height - the new requested height for the applet.
- Overrides:
- resize in class Component
resize
public void resize(Dimension d)
- Requests that this applet be resized.
- Parameters:
- d - an object giving the new width and height.
- Overrides:
- resize in class Component
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 window, where the application can inform users of its current state.
- Parameters:
- msg - a string to display in the status window.
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.
- Parameters:
- url - an absolute URL giving the location of the image.
- Returns:
- the image at the specified URL.
- See Also:
- 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.
- Parameters:
- url - an absolute URL giving the base location of the image.
- name - the location of the image, relative to the
url
argument. - Returns:
- the image at the specified URL.
- See Also:
- Image
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.
- Parameters:
- url - an absolute URL giving the location of the audio clip.
- Returns:
- the audio clip at the specified URL.
- See Also:
- AudioClip
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.
- Parameters:
- url - an absolute URL giving the base location of the audio clip.
- name - the location of the audio clip, relative to the
url
argument. - Returns:
- the audio clip at the specified URL.
- See Also:
- AudioClip
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
.
- Returns:
- a string containing information about the author, version, and copyright of the applet.
getLocale
public Locale getLocale()
- Gets the Locale for the applet, if it has been set. If no Locale has been set, then the default Locale is returned.
- Returns:
- [Needs to be documented!]
- Overrides:
- getLocale in class Component
getParameterInfo
public String[][] getParameterInfo()
- Returns information about the parameters than 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
.
- Returns:
- an array describing the parameters this applet looks for.
play
public void play(URL url)
- Plays the audio clip at the specified absolute URL. Nothing happens if the audio clip cannot be found.
- Parameters:
- 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 is relative to it. Nothing happens if the audio clip cannot be found.
- Parameters:
- url - an absolute URL giving the base location of the audio clip.
- name - the location of the audio clip, relative to the
url
argument.
init
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.
- See Also:
- destroy, start, stop
start
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.
The implementation of this method provided by the Applet
class does nothing.
- See Also:
- destroy, init, stop
stop
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.
- See Also:
- destroy, init
destroy
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.
- See Also:
- init, start, stop
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