可重置的Java计时器 [英] Resettable Java Timer

问题描述

我希望在java中有一个带有可重置时间的java.utils.Timer。我需要在X秒内设置一次性事件。如果在创建计时器和X秒之间没有任何反应，则事件正常发生。

I'd like to have a java.utils.Timer with a resettable time in java.I need to set a once off event to occur in X seconds. If nothing happens in between the time the timer was created and X seconds, then the event occurs as normal.

但是，如果在X秒过去之前，我决定事件应该在Y秒之后发生，那么我希望能告诉计时器重置它时间，以便事件在Y秒内发生。
例如计时器应该能够执行以下操作：

If, however, before X seconds has elapsed, I decide that the event should occur after Y seconds instead, then I want to be able to tell the timer to reset its time so that the event occurs in Y seconds. E.g. the timer should be able to do something like:

Timer timer = new Timer();  
timer.schedule(timerTask, 5000); //Timer starts in 5000 ms (X)

//At some point between 0 and 5000 ms...  
setNewTime(timer, 8000);  //timerTask will fire in 8000ms from NOW (Y).

我没有看到使用utils计时器的方法，就好像你调用cancel（ ）你不能再安排它。

I don't see a way to do this using the utils timer, as if you call cancel() you cannot schedule it again.

我接近复制这种行为的唯一方法是使用javax.swing.Timer并涉及停止原始计时器，以及创造一个新的。即：

The only way I've come close to replicating this behavior is by using javax.swing.Timer and involves stopping the origional timer, and creating a new one. i.e.:

timer.stop();
timer = new Timer(8000, ActionListener);
timer.start();

有更简单的方法吗？

推荐答案

根据 计时器 文档，在Java 1.5及更高版本中，您应该更喜欢 ScheduledThreadPoolExecutor 。 （您可能希望使用 <$创建此执行程序c $ c>执行者 .newSingleThreadScheduledExecutor（）易于使用;它创建的东西很像计时器。）

According to the Timer documentation, in Java 1.5 onwards, you should prefer the ScheduledThreadPoolExecutor instead. (You may like to create this executor using Executors.newSingleThreadScheduledExecutor() for ease of use; it creates something much like a Timer.)

很酷的是，当你安排任务时（通过调用 schedule（）），它返回 ScheduledFuture 对象。您可以使用它来取消计划任务。然后，您可以自由地提交具有不同触发时间的新任务。

The cool thing is, when you schedule a task (by calling schedule()), it returns a ScheduledFuture object. You can use this to cancel the scheduled task. You're then free to submit a new task with a different triggering time.

ETA：链接的计时器文档没有说明 ScheduledThreadPoolExecutor ，但 OpenJDK 版本有这样的说法：

ETA: The Timer documentation linked to doesn't say anything about ScheduledThreadPoolExecutor, however the OpenJDK version had this to say:

Java 5.0引入了 java.util.concurrent package和
其中一个并发实用程序是
ScheduledThreadPoolExecutor 这是一个线程池，用于以给定的速率重复
执行任务或延迟。对于计时器 / TimerTask
组合，它实际上是一个更多的
多功能替代品，因为它允许多个服务线程，接受各种
时间单位，并且不需要子类化 TimerTask （只需
工具 Runnable ）。使用一个线程配置
ScheduledThreadPoolExecutor 使其相当于
计时器。

Java 5.0 introduced the java.util.concurrent package and one of the concurrency utilities therein is the ScheduledThreadPoolExecutor which is a thread pool for repeatedly executing tasks at a given rate or delay. It is effectively a more versatile replacement for the Timer/TimerTask combination, as it allows multiple service threads, accepts various time units, and doesn't require subclassing TimerTask (just implement Runnable). Configuring ScheduledThreadPoolExecutor with one thread makes it equivalent to Timer.

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