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java.lang.Object java.util.TimerTask
public abstract class TimerTask
A task that can be scheduled for one-time or repeated execution by a Timer.
Timer
Constructor Summary | |
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protected |
TimerTask()
Creates a TimerTask and marks it as not yet scheduled. |
Method Summary | |
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boolean |
cancel()
Marks the task as canceled and prevents any further execution. |
abstract void |
run()
The TimerTask must implement a run method that will be called by the Timer when the 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. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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protected TimerTask()
Method Detail |
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public boolean cancel()
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.
public abstract void run()
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
.
run
in interface Runnable
public long scheduledExecutionTime()
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()
.
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