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为什么不推荐使用thread.stop而不支持timer.cancel？

[英]Why thread.stop deprecated and timer.cancel is not?

原文 2011-06-27 19:04:50 7 3 java

What is the difference between stopping a java Thread and stopping an instance of Timer ? 停止java Thread和停止Timer实例有什么区别？

Why is timer.cancel thread safe or is it ? 为什么timer.cancel线程安全或者是它？

3 个解决方案

Cancelling a timer doesn't have any of the potentially destabilizing behaviour of aborting a thread. 取消计时器不具有中止线程的任何潜在的不稳定行为。 From the docs : 来自文档：

Does not interfere with a currently executing task (if it exists). 不干扰当前正在执行的任务（如果存在）。

In other words, it's not going to try to stop a task which is already running, which could potentially end up with monitors not being released etc. It's just going to avoid running any more tasks. 换句话说，它不会试图阻止其已在运行的任务，这有可能与未在发布等监控者，它只是要避免运行任何更多的任务结束了。

Timer.cancel only cancels timer tasks that have not yet been started. Timer.cancel仅取消尚未启动的计时器任务。 The Thread.stop method stops the thread (by throwing an Error ) and may leave the system in an inconsistent state, since the thread is stopped in an unknown place, possibly while doing something. Thread.stop方法停止线程（通过抛出Error ）并且可能使系统处于不一致状态，因为线程在未知位置停止，可能在执行某些操作时。

Java's Timer implementation uses a loop and a flag to indicate whether its underlying Thread should continue processing timer events. Java的Timer实现使用循环和标志来指示其底层Thread是否应该继续处理计时器事件。 When you call cancel() , the newTasksMayBeScheduled flag is set to false, which clears any pending events, and causes the thread's loop to stop (allowing its run() method to return). 当你调用cancel() ， newTasksMayBeScheduled标志被设置为false，它清除所有挂起的事件，并导致线程的循环停止（允许其run()方法返回）。 In other words, it does not use the unsafe Thread#stop() method. 换句话说，它不使用不安全的Thread#stop()方法。