This document discusses the applet skeleton in Java. It explains that applets override lifecycle methods like init(), start(), stop(), and destroy() to control their execution states. These methods are defined in the Applet class. It provides a code example of an applet skeleton that implements these methods, as well as the paint() method defined in the Component class. When run, this skeleton applet generates a window to display itself.

1. Applet skeleton
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2. Objectives
On completion of this period, you would be able
to learn
• Applet Skeleton
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3. Recap
In the last class, you have studied about the life cycle of an
applet
• Applet life cycle has different state
– Born
– Running
– Idle
– Dead
• The method useful for these state change
– init()
– start()
– stop()
– paint()
– destroy()
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4. Applet Skeleton
• All but the most trivial applets override a set of
methods that provides the basic mechanism
• Applet viewer interfaces to the applet and
controls its execution
• Applet methods are, init( ), start( ), stop( ), and
destroy( )
• All these methods already are defined by
Applet
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5. Applet Skeleton contd…
• paint( ), is defined by the AWT Component
class
• Applets do not need to override those methods
they do not use
• However, only very simple applets will not need
to define all of them
• These methods can be assembled into the
skeleton shown in next slide
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6. Applet Skeleton contd…
import java.awt.*;
import java.applet.*;
/*
<applet code="AppletSkel"width=300height=100>
</applet>
*/
public class AppletSkel extends Applet {
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7. Applet Skeleton contd…
// Called first
public void init() {
// initialization
}
/* Called second, after init(). Also called whenever
the applet is restarted. */
public void start() {
// start or resume execution
}
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8. Applet Skeleton contd..
// Called when the applet is stopped
public void stop(){
// suspends execution
}
/* Called when applet is terminated. This is the last
method executed. */
public void destroy() {
// perform shutdown activities
}
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9. Applet Skeleton contd..
// Called when an applet's window must be restored
public void paint (Graphics g) {
// redisplay contents of window
}
}
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10. Applet Skeleton contd..
• When Applet runs, it generates the window
shown below
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11. Summary
In this class, you have learnt
• All but the most trivial applets override a set of
methods that provides the basic mechanism by which
the browser or
• Applet methods are, init( ), start( ), stop( ), and
destroy( )
• These methods can be assembled into the skeleton
shown as shown in the code
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12. Quiz
1. Which class defines paint() method
a) Applet
b) Component
c) AWT
d) None
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13. Frequently Asked Questions
1. Write applet skeleton code
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