. lang。android.view ClassCastException。视图不能被转换为android.viewgroup。

I am now implementing a drag and drop operation . In this operation drag from a relative layout to anther one is allowed . If there's a child in a layout and another image is drag to it the images must exchange position . Here's my problem when i cast a view to view group , Class cast exception occurs . I really don't know how to solve it as I'm a new to android . The error line at log cat points at this ((ViewGroup)parent).addView(nextChild). Please give me advice . Sorry if my question bother you .I am now implementing a drag and drop operation