ClassCastException：转换为已创建的接口问题？

Question

public class MyPostsScreen extends Fragment implements
    LoaderManager.LoaderCallbacks<Cursor>, MediaStoreAdapter.OnClickThumbListener{

    private OnFragmentInteractionListener mListener;

    private final static int READ_EXTERNAL_STORAGE_PERMMISSION_RESULT = 0;
    private final static int MEDIASTORE_LOADER_ID = 0;
    private RecyclerView mThumbnailRecyclerView;
    private MediaStoreAdapter mMediaStoreAdapter;

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


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_my_posts_screen, container, false);

        mThumbnailRecyclerView = (RecyclerView) v.findViewById(R.id.thumbnailRv);
        GridLayoutManager gridLayoutManager = new GridLayoutManager(this.getContext(), 3);
        mThumbnailRecyclerView.setLayoutManager(gridLayoutManager);
        mMediaStoreAdapter = new MediaStoreAdapter(this.getActivity());
        mThumbnailRecyclerView.setAdapter(mMediaStoreAdapter);

        checkReadExternalStoragePermission();

        // Inflate the layout for this fragment
        return v;
    }
}

public class MediaStoreAdapter extends RecyclerView.Adapter<MediaStoreAdapter.ViewHolder> {
    private Cursor mMediaStoreCursor;
    private final Activity mActivity;
    private OnClickThumbListener mOnClickThumbListener;

    public interface OnClickThumbListener {
        void OnClickImage(Uri imageUri);
        void OnClickVideo(Uri videoUri);
    }
    public MediaStoreAdapter(Activity activity) {
        this.mActivity = activity;
        //TODO: Figure out why this fails Java Class Exception, and FIX.
        this.mOnClickThumbListener = (OnClickThumbListener)activity;
    }
}

Answer 1

将其更改为

private final Context mActivity;
....
....

public MediaStoreAdapter(Context context, OnClickThumbListener onClickThumbListener) {
    this.mActivity = context;
    this.mOnClickThumbListener = onClickThumbListener;

}

在MyPostsScreen片段中，调用适配器构造函数，如下所示，

mMediaStoreAdapter = new MediaStoreAdapter(this.getActivity(), this);
mThumbnailRecyclerView.setAdapter(mMediaStoreAdapter);

这是因为您的接口是由片段实现的，而不是由MainActivity实现的。