- java.lang.Object
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- java.awt.Component
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- java.awt.Container
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- java.awt.Panel
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- java.applet.Applet
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- All Implemented Interfaces:
- ImageObserver, MenuContainer, Serializable, Accessible
- Direct Known Subclasses:
- JApplet
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. TheApplet
class provides a standard interface between applets and their environment.- Since:
- JDK1.0
- See Also:
- Serialized Form
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Nested Class Summary
Nested Classes Modifier and Type Class and Description protected class
Applet.AccessibleApplet
This class implements accessibility support for theApplet
class.-
Nested classes/interfaces inherited from class java.awt.Panel
Panel.AccessibleAWTPanel
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Nested classes/interfaces inherited from class java.awt.Container
Container.AccessibleAWTContainer
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Nested classes/interfaces inherited from class java.awt.Component
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
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Field Summary
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Fields inherited from class java.awt.Component
BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
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Constructor Summary
Constructors Constructor and Description Applet()
Constructs a new Applet.
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Method Summary
Methods Modifier and Type Method and Description 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.AccessibleContext
getAccessibleContext()
Gets the AccessibleContext associated with this Applet.AppletContext
getAppletContext()
Determines this applet's context, which allows the applet to query and affect the environment in which it runs.String
getAppletInfo()
Returns information about this applet.AudioClip
getAudioClip(URL url)
Returns theAudioClip
object specified by theURL
argument.AudioClip
getAudioClip(URL url, String name)
Returns theAudioClip
object specified by theURL
andname
arguments.URL
getCodeBase()
Gets the base URL.URL
getDocumentBase()
Gets the URL of the document in which this applet is embedded.Image
getImage(URL url)
Returns anImage
object that can then be painted on the screen.Image
getImage(URL url, String name)
Returns anImage
object that can then be painted on the screen.Locale
getLocale()
Gets the locale of the applet.String
getParameter(String name)
Returns the value of the named parameter in the HTML tag.String[][]
getParameterInfo()
Returns information about the parameters that are understood by this applet.void
init()
Called by the browser or applet viewer to inform this applet that it has been loaded into the system.boolean
isActive()
Determines if this applet is active.boolean
isValidateRoot()
Indicates if this container is a validate root.static AudioClip
newAudioClip(URL url)
Get an audio clip from the given URL.void
play(URL url)
Plays the audio clip at the specified absolute URL.void
play(URL url, String name)
Plays the audio clip given the URL and a specifier that is relative to it.void
resize(Dimension d)
Requests that this applet be resized.void
resize(int width, int height)
Requests that this applet be resized.void
setStub(AppletStub stub)
Sets this applet's stub.void
showStatus(String msg)
Requests that the argument string be displayed in the "status window".void
start()
Called by the browser or applet viewer to inform this applet that it should start its execution.void
stop()
Called by the browser or applet viewer to inform this applet that it should stop its execution.-
Methods inherited from class java.awt.Panel
addNotify
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Methods inherited from class java.awt.Container
add, add, add, add, add, addContainerListener, addImpl, 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, paramString, preferredSize, print, printComponents, processContainerEvent, processEvent, remove, remove, removeAll, removeContainerListener, removeNotify, setComponentZOrder, setFocusCycleRoot, setFocusTraversalKeys, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setFont, setLayout, transferFocusDownCycle, update, validate, validateTree
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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, getGraphics, 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, 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
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Constructor Detail
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Applet
public Applet() throws HeadlessException
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 injava.applet.Applet
in the constructor.- Throws:
HeadlessException
- if GraphicsEnvironment.isHeadless() returns true.- Since:
- 1.4
- See Also:
GraphicsEnvironment.isHeadless()
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Method Detail
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setStub
public final void setStub(AppletStub stub)
Sets this applet's stub. This is done automatically by the system.If there is a security manager, its
checkPermission
method is called with theAWTPermission("setAppletStub")
permission if a stub has already been set.- Parameters:
stub
- the new stub.- Throws:
SecurityException
- if the caller cannot set the stub
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isActive
public boolean isActive()
Determines if this applet is active. An applet is marked active just before itsstart
method is called. It becomes inactive just before itsstop
method is called.
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getDocumentBase
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:
The document base is:http://java.sun.com/products/jdk/1.2/index.html
http://java.sun.com/products/jdk/1.2/index.html
- Returns:
- the
URL
of the document that contains this applet. - See Also:
getCodeBase()
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getCodeBase
public URL getCodeBase()
Gets the base URL. This is the URL of the directory which contains this applet.- Returns:
- the base
URL
of the directory which contains this applet. - See Also:
getDocumentBase()
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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,
or
null
if not set.
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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.
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resize
public void resize(int width, int height)
Requests that this applet be resized.
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resize
public void resize(Dimension d)
Requests that this applet be resized.
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isValidateRoot
public boolean isValidateRoot()
Indicates if this container is a validate root.Applet
objects are the validate roots, and, therefore, they override this method to returntrue
.- Overrides:
isValidateRoot
in classContainer
- Returns:
true
- Since:
- 1.7
- See Also:
Container.isValidateRoot()
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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.
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getImage
public Image getImage(URL url)
Returns anImage
object that can then be painted on the screen. Theurl
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
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getImage
public Image getImage(URL url, String name)
Returns anImage
object that can then be painted on the screen. Theurl
argument must specify an absolute URL. Thename
argument is a specifier that is relative to theurl
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 theurl
argument.- Returns:
- the image at the specified URL.
- See Also:
Image
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newAudioClip
public static final AudioClip newAudioClip(URL url)
Get an audio clip from the given URL.- Parameters:
url
- points to the audio clip- Returns:
- the audio clip at the specified URL.
- Since:
- 1.2
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getAudioClip
public AudioClip getAudioClip(URL url)
Returns theAudioClip
object specified by theURL
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
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getAudioClip
public AudioClip getAudioClip(URL url, String name)
Returns theAudioClip
object specified by theURL
andname
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 theurl
argument.- Returns:
- the audio clip at the specified URL.
- See Also:
AudioClip
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getAppletInfo
public String getAppletInfo()
Returns information about this applet. An applet should override this method to return aString
containing information about the author, version, and copyright of the applet.The implementation of this method provided by the
Applet
class returnsnull
.- Returns:
- a string containing information about the author, version, and copyright of the applet.
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getLocale
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.- Overrides:
getLocale
in classComponent
- Returns:
- the locale of the applet; if no locale has been set, the default locale is returned.
- Since:
- JDK1.1
- See Also:
Component.setLocale(java.util.Locale)
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getParameterInfo
public String[][] getParameterInfo()
Returns information about the parameters that are understood by this applet. An applet should override this method to return an array ofStrings
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 returnsnull
.- Returns:
- an array describing the parameters this applet looks for.
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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.
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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 theurl
argument.
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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 thestart
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 theinit
method to create the threads and thedestroy
method to kill them.The implementation of this method provided by the
Applet
class does nothing.
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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 theinit
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 thestart
method to resume animation, and thestop
method to suspend the animation.Note: some methods, such as
getLocationOnScreen
, can only provide meaningful results if the applet is showing. BecauseisShowing
returnsfalse
when the applet'sstart
is first called, methods requiringisShowing
to returntrue
should be called from aComponentListener
.The implementation of this method provided by the
Applet
class does nothing.
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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 thestart
method to resume animation, and thestop
method to suspend the animation.The implementation of this method provided by the
Applet
class does nothing.
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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. Thestop
method will always be called beforedestroy
.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 theinit
method to create the threads and thedestroy
method to kill them.The implementation of this method provided by the
Applet
class does nothing.
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getAccessibleContext
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.- Specified by:
getAccessibleContext
in interfaceAccessible
- Overrides:
getAccessibleContext
in classPanel
- Returns:
- an AccessibleApplet that serves as the AccessibleContext of this Applet
- Since:
- 1.3
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Document heeft de 11/06/2005 gemaakt, de laatste keer de 04/03/2020 gewijzigd
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