如何TimerTask的Andr​​oid上管理线程？ [英] How does TimerTask on Android manages threads?

问题描述

我不知道怎么一个TimerTask正在与线程。

I was wondering how the TimerTask is working with threads.

例如，我有一个执行TimerTask的，它有它运行在UI线程一个'运行'方法的code。

For example, I've got a code that executes a TimerTask, which has a 'run' method which will run on the UI Thread.

class looper extends TimerTask {

    public looper() {

    }

    public void run() {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                timer.schedule(new looper(), new Date(new Date().getTime() + 100));
            }
        });
    }
}

和计时器就开始这样的：

and the timer would start like this:

    timer = new Timer();
    timer.schedule(new looper(), new Date());

请问TimerTask的创建一个新的线程？如果是这样，如何​​ runOnUiThread 将工作？将它移到了code到UI线程？

Will the TimerTask create a new thread? if so, how does runOnUiThread will work? will it move the code to the UI thread?

我试过，无需再次调用TimerTask的（ timer.schedule ），只是使用在运行一个无限循环来进行计算 - 但会阻止用户界面线程和应用程序不响应

I've tried to eliminate the need to call the TimerTask again (timer.schedule) and just use an infinite loop inside the run to make calculations - but that would block the UI thread and the app will not respond.

PS - 我必须在UI线程上的code运行，因为它有更新UI

P.S - I must have the code run on the UI thread, because it has to update the UI.

那么，到底是怎么回事？

So, what's going on here?

推荐答案

关于你的问题：

• runOnUiThread 从文档：

运行在UI线程上指定的操作。如果当前线程是UI线程，则该动作被立即执行。如果当前线程不是UI线程，该操作被张贴到UI线程的事件队列。

Runs the specified action on the UI thread. If the current thread is the UI thread, then the action is executed immediately. If the current thread is not the UI thread, the action is posted to the event queue of the UI thread.

在code在TimerTask的是在不同的线程中执行，所以你应该叫 runOnUiThread 执行code。

The code at TimerTask it is executed on a different thread, so you should call runOnUiThread to execute code.

您这样做是对的，但你为什么要重新创建一个TimerTask的run方法？考虑使用 scheduleAtFixedTime 时，100会期及延迟0。 run方法，然后将执行它应该做的工作。

You are doing it right, but why are you re-creating the timertask at the run method ? Consider using scheduleAtFixedTime , the 100 will be the period and the delay 0. The run method then will execute the task it is supposed to do.

    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            //do whatever
        }
    });

<一个href="http://developer.android.com/reference/java/util/Timer.html#scheduleAtFixedRate%28java.util.TimerTask,%20java.util.Date,%20long%29"相对=nofollow> scheduleAtFixedTime

*的更新：

如果其更新到视图，最好是使用 handler.postDelayed ，看到一个<一个href="http://stackoverflow.com/questions/6242268/repeat-a-task-with-a-time-delay?answertab=votes#tab-top">example这里它将在UI线程上的延迟之后执行。

If its an update to a view it is better to use handler.postDelayed, see an example here it will be executed after a delay on the UI thread.

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