列表视图和动画

我使用的ListView动画从API演示，例如2.下面是从onCreate方法的代码片段：

I'm using listview animation from API DEMOS, example 2. here's the snippet from OnCreate method:

ListView listview = (ListView) findViewById(android.R.id.list);

AnimationSet set = new AnimationSet(true);
Animation animation = new AlphaAnimation(0.0f, 1.0f);
animation.setDuration(50);
set.addAnimation(animation);

animation = new TranslateAnimation(
    Animation.RELATIVE_TO_SELF, 0.0f, Animation.RELATIVE_TO_SELF, 0.0f,
    Animation.RELATIVE_TO_SELF, -1.0f, Animation.RELATIVE_TO_SELF, 0.0f);

animation.setDuration(200);
set.addAnimation(animation);

LayoutAnimationController controller = new LayoutAnimationController(set, 0.5f);
listview.setLayoutAnimation(controller);

在未来的某个时候， notifyDataSetInvalidated（）是在列表的接口调用，并且我的列表刷新。但项不会在动画中显示的任何更多。

At some point in the future, notifyDataSetInvalidated() is called upon list's adapter, and my list is refreshed. but the items are not shown in animation any more.

请帮忙。