Methods for Milestones
The Applet class provides a framework for applet execution, defining methods that the system calls when milestones occur. Milestones are major events in an applet's life cycle. Most applets override some or all of these methods to respond appropriately to milestones.
init method is useful for one-time initialization that doesn't take very long. The
init method typically contains the code that you would normally put into a constructor. The reason applets don't usually have constructors is that they aren't guaranteed to have a full environment until their
init method is called. Keep the
init method short so that your applet can load quickly.
Every applet that performs tasks after initialization (except in direct response to user actions) must override the
start method. The
start method starts the execution of the applet. It is good practice to return quickly from the
start method. If you need to perform computationally intensive operations it might be better to start a new thread for this purpose.
Most applets that override the
start should also override the
stop method. The
stop method should suspend the applet's execution, so that it doesn't take up system resources when the user isn't viewing the applet's page. For example, an applet that displays an animation should stop trying to draw the animation when the user isn't viewing it.
Many applets don't need to override the
destroy method because their
stop method (which is called before
destroy ) will perform all tasks necessary to shut down the applet's execution. However, the
destroy method is available for applets that need to release additional resources.
Keep implementations of the
destroy method as short as possible, because there is no guarantee that this method will be completely executed. The Java Virtual Machine might exit before a long
destroy method has completed.