为什么动画在计时器滴答声时重新启动

Question

我有一个看动画和计时器的课。这是我的onCreate方法的内容：

    chronometer = ((Chronometer) findViewById(R.id.clock_time));
    chronometer.setOnChronometerTickListener(this);
    chronometer.start();
    v = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
    final SurfaceView surfaceViewTimer = (SurfaceView) findViewById(R.id.surface_view_timer);
    final RelativeLayout timeView = (RelativeLayout) findViewById(R.id.time_view);
    ViewTreeObserver observer = timeView.getViewTreeObserver();
    observer.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            int animationDuration = getIntent().getIntExtra(
                    MainActivity.TOTAL_TIME, -1);
            TranslateAnimation surfaceGrowingAnimation = new TranslateAnimation(
                    0, 0, timeView.getHeight(), 0);
            surfaceGrowingAnimation.setDuration(animationDuration * 1000);          
            surfaceViewTimer.startAnimation(surfaceGrowingAnimation);

我对计时器还有另一种方法：

@Override
public void onChronometerTick(Chronometer chronometer) {
    int intervalOfVibration = getIntent().getIntExtra(
            MainActivity.VIBRATION_INTERVAL, -1);
    long elapsedMillis = (SystemClock.elapsedRealtime() - ((Chronometer) findViewById(R.id.clock_time))
            .getBase()) / 1000;
    if (((elapsedMillis % intervalOfVibration) == 0) && (elapsedMillis > 0))
        v.vibrate(300);
}

但是我的动画会在计时器的每次滴答声中重新启动。

我该如何解决这个问题？

现在我收到这些错误：

11-26 17:58:57.908: W/dalvikvm(15596): threadid=3: thread exiting with uncaught exception (group=0x2aaca228)
11-26 17:58:57.908: E/AndroidRuntime(15596): Uncaught handler: thread main exiting due to uncaught exception
11-26 17:58:57.908: E/AndroidRuntime(15596): java.lang.IllegalStateException: This ViewTreeObserver is not alive, call getViewTreeObserver() again
11-26 17:58:57.908: E/AndroidRuntime(15596):    at android.view.ViewTreeObserver.checkIsAlive(ViewTreeObserver.java:492)
11-26 17:58:57.908: E/AndroidRuntime(15596):    at android.view.ViewTreeObserver.removeGlobalOnLayoutListener(ViewTreeObserver.java:339)
11-26 17:58:57.908: E/AndroidRuntime(15596):    at com.activities.TimerActivity$1.onGlobalLayout(TimerActivity.java:64)
11-26 17:58:57.908: E/AndroidRuntime(15596):    at android.view.ViewTreeObserver.dispatchOnGlobalLayout(ViewTreeObserver.java:549)

Answer 1

每次

屏幕布局时都会调用您的OnGlobalLayoutListener，其中包括每次Chronometer更改时（因为它会更改宽度，可能的高度等，并且所有内容都无效）。

在onGlobalLayout()方法中使用removeOnGlobalLayoutListener();：

ViewTreeObserver observer = timeView.getViewTreeObserver(); // Make this final
observer.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
    @Override
    @SuppressWarnings("deprecation")
    public void onGlobalLayout() {
        // Your code ...
        if (android.os.Build.VERSION.SDK_INT < 16) // Use old, deprecated method
            timeView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
        else // Use new method
            timeView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
    }
}

注意：对于 API <16，您必须改用removeGlobalOnLayoutListener()。（方法名称已在 API 级别 16 中更改。它们以相同的方式执行。