android - fragment 中的接口(interface)类有什么用？

Question

我创建了一个 fragment ，但找不到该 fragment 中接口(interface)类的用途...我用谷歌搜索但找不到正确的文档？

感谢您的关心!

public class SongListFragment extends Fragment {

        public SongListFragment() {
            // Required empty public constructor
        }

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            if (getArguments() != null) {
                songIds = getArguments().getIntArray(SONG_IDS);
            }
        }
      @Override
        public void onAttach(Context context) {
            super.onAttach(context);
            if (context instanceof OnFragmentInteractionListener) {
                mListener = (OnFragmentInteractionListener) context;
            } else {
                throw new RuntimeException(context.toString()
                        + " must implement OnFragmentInteractionListener");
            }
        }



//what's the use?  
public interface OnFragmentInteractionListener {
            public void onSongSelected(int songId);
        }
}

Answer 1

OnFragmentInteractionListener 可用于 communicate fragment 之间

To allow a Fragment to communicate up to its Activity, you can define an interface in the Fragment class and implement it within the Activity. The Fragment captures the interface implementation during its onAttach() lifecycle method and can then call the Interface methods in order to communicate with the Activity.

查找另一个 SO 示例 here