java.util
Class TimerTask
- Runnable
Task that can be run at a later time if given to a Timer.
The TimerTask must implement a run method that will be called by the
Timer when the task is scheduled for execution. The task can check when
it should have been scheduled and cancel itself when no longer needed.
Example:
Timer timer = new Timer();
TimerTask task = new TimerTask() {
public void run() {
if (this.scheduledExecutionTime() < System.currentTimeMillis() + 500)
// Do something
else
// Complain: We are more then half a second late!
if (someStopCondition)
this.cancel(); // This was our last execution
};
timer.scheduleAtFixedRate(task, 1000, 1000); // schedule every second
Note that a TimerTask object is a one shot object and can only given once
to a Timer. (The Timer will use the TimerTask object for bookkeeping,
in this implementation).
This class also implements
Runnable to make it possible to
give a TimerTask directly as a target to a
Thread.
TimerTask()- Creates a TimerTask and marks it as not yet scheduled.
|
boolean | cancel()- Marks the task as canceled and prevents any further execution.
|
abstract void | run()- Method that is called when this task is scheduled for execution.
|
long | scheduledExecutionTime()- Returns the last time this task was scheduled or (when called by the
task from the run method) the time the current execution of the task
was scheduled.
|
clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait |
TimerTask
protected TimerTask()
Creates a TimerTask and marks it as not yet scheduled.
cancel
public boolean cancel()
Marks the task as canceled and prevents any further execution.
Returns true if the task was scheduled for any execution in the future
and this cancel operation prevents that execution from happening.
A task that has been canceled can never be scheduled again.
In this implementation the TimerTask it is possible that the Timer does
keep a reference to the TimerTask until the first time the TimerTask
is actually scheduled. But the reference will disappear immediatly when
cancel is called from within the TimerTask run method.
run
public abstract void run()
Method that is called when this task is scheduled for execution.
- run in interface Runnable
scheduledExecutionTime
public long scheduledExecutionTime()
Returns the last time this task was scheduled or (when called by the
task from the run method) the time the current execution of the task
was scheduled. When the task has not yet run the return value is
undefined.
Can be used (when the task is scheduled at fixed rate) to see the
difference between the requested schedule time and the actual time
that can be found with
System.currentTimeMillis().
TimerTask.java -- Task that can be run at a later time if given to a Timer.
Copyright (C) 2000 Free Software Foundation, Inc.
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