程序包 java.util

类 TimerTask

java.lang.Object

java.util.TimerTask

所有已实现的接口:

Runnable

public abstract class TimerTask
extends Object
implements Runnable

A task that can be scheduled for one-time or repeated execution by a Timer.

从以下版本开始:

1.3

另请参阅:

Timer

构造器概要

构造器

限定符	构造器	说明
protected	TimerTask()	Creates a new timer task.

方法概要

限定符和类型	方法	说明
boolean	cancel()	Cancels this timer task.
abstract void	run()	The action to be performed by this timer task.
long	scheduledExecutionTime()	Returns the scheduled execution time of the most recent actual execution of this task.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

构造器详细资料

TimerTask

protected TimerTask()

Creates a new timer task.

方法详细资料

run

public abstract void run()

The action to be performed by this timer task.

指定者:

run 在接口中 Runnable

另请参阅:

Thread.run()

cancel

public boolean cancel()

Cancels this timer task. If the task has been scheduled for one-time execution and has not yet run, or has not yet been scheduled, it will never run. If the task has been scheduled for repeated execution, it will never run again. (If the task is running when this call occurs, the task will run to completion, but will never run again.)

Note that calling this method from within the run method of a repeating timer task absolutely guarantees that the timer task will not run again.

This method may be called repeatedly; the second and subsequent calls have no effect.

返回:

true if this task is scheduled for one-time execution and has not yet run, or this task is scheduled for repeated execution. Returns false if the task was scheduled for one-time execution and has already run, or if the task was never scheduled, or if the task was already cancelled. (Loosely speaking, this method returns true if it prevents one or more scheduled executions from taking place.)

scheduledExecutionTime

public long scheduledExecutionTime()

Returns the scheduled execution time of the most recent actual execution of this task. (If this method is invoked while task execution is in progress, the return value is the scheduled execution time of the ongoing task execution.)

This method is typically invoked from within a task's run method, to determine whether the current execution of the task is sufficiently timely to warrant performing the scheduled activity:

   public void run() {
       if (System.currentTimeMillis() - scheduledExecutionTime() >=
           MAX_TARDINESS)
               return;  // Too late; skip this execution.
       // Perform the task
   }
 

This method is typically not used in conjunction with fixed-delay execution repeating tasks, as their scheduled execution times are allowed to drift over time, and so are not terribly significant.

返回:

the time at which the most recent execution of this task was scheduled to occur, in the format returned by Date.getTime(). The return value is undefined if the task has yet to commence its first execution.

另请参阅:

Date.getTime()