Applet

 Introduction to Applet:

•  Applet is a one type java program.
•  The Applet class is contained in the java.applet package.
• All applets are subclasses of Applet.
• Applet is a java program and it runs in the viewer and browser.
• Here, following is the Applet class hierarchy.

Applet Life Cycle:

•  Java applet inherits a set of default behaviours from the Applet class.
• Applet has the following state.

               1)Born state

               2)Running state

               3)Idle and stopped state

               4)Dead State

1)Initialization State:

•  Applet enters the initialization state when it is first loaded.
•  This is achieved by calling the init() method of Applet class. 
•  The applet is born.
•  At this stage, we may do the following, if required.

                    o Create objects needed by the applet

                    o Setup initial values

                    o Load images or fonts

                    o Set up colors

•  The initialization occurs only once in the applet’s life cycle.
•  We must declare init() method in the born state.

            public void init()

           {

                       -----------

                       -----------(Action)

                       -----------

           }

2)Running state:

•  Applet enters the running state when the system calls the start() method of Applet class.
•  This occurs automatically after the applet is initialized.
•  For example, we may leave the web page containing the applet temporarily to another page and return back to the page. 
• This again starts the applet running.
•  Start() method may be called more than once.

                public void start()

               {

                           ------------

                           ------------(Action)

                           ------------

               }

3)Idle or Stopped state:

•  An applet becomes idle when it is stopped from running.
•  Stopping occurs automatically when we leave the page containing the currently running applet.
• We can also do so by calling the stop() method explicitly.
•  If we use a thread to run the applet, then we use a thread to run the applet, then we must use stop() method to terminate the thread.

             public void stop()

            {

                         ------------

                         ------------(Action)

                         ------------

            }

4)Dead state:

•  An applet is said to be dead when it is removed from memory.
•  This occurs automatically by invoking the destroy() method when we quit the browser.
•  Like initialization , destroying stage occurs only once in the applet life cycle.

           public void destroy()

          {

                    ------------

                    ------------(Action)

                    ------------

          }

5)Display state:

•  Applet moves to the display state whenever it has to perform some output operations on the screen.
•  This happens immediately after the applet enters into the running state.
•  The paint() method is called to complete this task.
•  Every applet have a paint method.
  

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