This abstract Runnable class represents a task that is scheduled with a Timer object for one-time or repeated execution in the future. You can define a task by subclassing TimerTask and implementing the abstract run( ) method. Schedule the task for future execution by passing an instance of your subclass to one of the schedule( ) or scheduleAtFixedRate( ) methods of Timer . The Timer object will then invoke the run( ) method at the scheduled time or times. Call cancel( ) to cancel the one-time or repeated execution of a TimerTask( ) . This method returns TRue if a pending execution was actually canceled . It returns false if the task has already been canceled, was never scheduled, or was scheduled for one-time execution and has already been executed. scheduledExecutionTime( ) returns the time in milliseconds at which the most recent execution of the TimerTask was scheduled to occur. When the host system is heavily loaded, the run( ) method may not be invoked exactly when scheduled. Some tasks may choose to do nothing if they are not invoked on time. The run( ) method can compare the return values of scheduledExecutionTime( ) and System.currentTimeMillis( ) to determine whether the current invocation is sufficiently timely . Figure 16-60. java.util.TimerTaskpublic abstract class TimerTask implements Runnable { // Protected Constructors protected TimerTask ( ); // Public Instance Methods public boolean cancel ( ); public long scheduledExecutionTime ( ); // Methods Implementing Runnable public abstract void run ( ); } Passed ToTimer.{schedule( ) , scheduleAtFixedRate( )} |