我下面http://developer.android.com/guide/topics/graphics/view-animation.html#frame-animation有细微的变化。我已决定把动画循环，并希望它从一开始就开始。

I am following http://developer.android.com/guide/topics/graphics/view-animation.html#frame-animation with minor changes. I have decided to make the animation loop and want it to start from the get-go.

我的动画是绘制/ listening.xml：

My animation is at drawable/listening.xml:

<animation-list
xmlns:android="http://schemas.android.com/apk/res/android"
android:oneshot="false">
<item
    android:drawable="@drawable/l_01"
    android:duration="200" />
<item
    android:drawable="@drawable/l_02"
    android:duration="200" />
<item
    android:drawable="@drawable/l_03"
    android:duration="200" />
</animation-list>

和我的初始化code：

and my init code:

 @Override public void onWindowFocusChanged(boolean hasFocus)  { 
      super.onWindowFocusChanged(hasFocus); 
      animImg = (ImageView)findViewById(R.id.listen_anim);
      animImg.setBackgroundResource(R.drawable.listening);
      anim = (AnimationDrawable) animImg.getBackground(); 
      anim.start();
 };

我看到的是第一帧，没有其他的图像。

All I see is the first frame and no other images.

推荐答案

在onResume（）运行此：

Run this in onResume():

class AnimTask extends AsyncTask<String, String,String> {
            Activity act;
            AnimTask(Activity act) {
                this.act = act;
            }

            @Override
            protected String doInBackground(String... params) {
                act.runOnUiThread(new Runnable() {
                    public void run(){
                        animImg = (ImageView)findViewById(R.id.listen_anim);
                        animImg.setBackgroundResource(R.drawable.listening);
                        anim = (AnimationDrawable) animImg.getBackground();
                        anim.start();
                    }
                });
                return null;
            }
        }