Applet Life Cycle

The life cycle of an applet is as shown in the figure below:

• As shown in the above diagram, the life cycle of an applet starts with init() method and ends with destroy() method.
• Other life cycle methods are start(), stop() and paint(). 
• The methods to execute only once in the applet life cycle are init() and destroy(). 
• Other methods execute multiple times.

Below is the description of each applet life cycle method:

init(): 

• The init() method is the first method to execute when the applet is executed. 
• Variable declaration and initialization operations are performed in this method.

start(): 

• The start() method contains the actual code of the applet that should run. 
• The start() method executes immediately after the init() method.
• It also executes whenever the applet is restored, maximized or moving from one tab to another tab in the browser.

stop(): 

• The stop() method stops the execution of the applet. 
• The stop() method executes when the applet is minimized or when moving from one tab to another in the browser.

destroy(): 

• The destroy() method executes when the applet window is closed or when the tab containing the webpage is closed. 
• stop() method executes just before when destroy() method is invoked. 
• The destroy() method removes the applet object from memory.

paint(): 

• The paint() method is used to redraw the output on the applet display area. 
• The paint() method executes after the execution of start() method and whenever the applet or browser is resized.

The method execution sequence when an applet is executed is:

• init()
• start()
• paint()

The method execution sequence when an applet is closed is:

• stop()
• destroy()

Example program that demonstrates the life cycle of an applet is as follows:

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import java.awt.*; import java.applet.*; public class MyApplet extends Applet { public void init() { System.out.println("Applet initialized"); } public void start() { System.out.println("Applet execution started"); } public void stop() { System.out.println("Applet execution stopped"); } public void paint(Graphics g) { System.out.println("Painting..."); } public void destroy() { System.out.println("Applet destroyed"); } }

Output of the above applet program when run using appletviewer tool is:

Applet initialized
Applet execution started
Painting…
Painting…
Applet execution stopped
Applet destroyed