Animating Layout Changes(展开收起)

原文地址：https://developer.android.com/training/animation/layout.html#add

（1）设置布局文件：

<LinearLayout android:id="@+id/container"
    android:animateLayoutChanges="true"
    ...
/>

（2）Java代码

private ViewGroup mContainerView;
...
private void addItem() {
    View newView;
    ...
    mContainerView.addView(newView, 0);
}