Java tutorial
package develop.d2ru.kpop.fragments; import android.app.ProgressDialog; import android.content.res.Resources; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.support.v7.widget.StaggeredGridLayoutManager; import android.util.Pair; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import com.google.api.services.youtube.YouTube; import com.google.api.services.youtube.model.Video; import java.util.List; import develop.d2ru.kpop.youtube.GetPlaylistAsyncTask; import develop.d2ru.kpop.model.Playlist; import develop.d2ru.kpop.adapter.PlaylistCardAdapter; import develop.d2ru.kpop.R; /** * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * <p/> * http://www.apache.org/licenses/LICENSE-2.0 * <p/> * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * <p/> * <p/> * YouTubeRecyclerViewFragment contains a RecyclerView that shows a list of YouTube video cards. * <p/> */ public class YouTubeRecyclerViewFragment extends Fragment { // the fragment initialization parameter private static final String ARG_YOUTUBE_PLAYLIST_ID = "YOUTUBE_PLAYLIST_ID"; // key used in the saved instance bundle to persist the playlist private static final String KEY_SAVED_INSTANCE_PLAYLIST = "SAVED_INSTANCE_PLAYLIST"; private String mPlaylistId; private RecyclerView mRecyclerView; private Playlist mPlaylist; private RecyclerView.LayoutManager mLayoutManager; private PlaylistCardAdapter mAdapter; private YouTube mYouTubeDataApi; private ProgressDialog pDialog; /** * Use this factory method to create a new instance of * this fragment using the provided parameters. * * * @param youTubeDataApi * @param playlistId The YouTube Playlist ID parameter string * @return A new instance of fragment YouTubeRecyclerViewFragment. */ public static YouTubeRecyclerViewFragment newInstance(YouTube youTubeDataApi, String playlistId) { YouTubeRecyclerViewFragment fragment = new YouTubeRecyclerViewFragment(); Bundle args = new Bundle(); args.putString(ARG_YOUTUBE_PLAYLIST_ID, playlistId); fragment.setArguments(args); fragment.setYouTubeDataApi(youTubeDataApi); return fragment; } public YouTubeRecyclerViewFragment() { // Required empty public constructor } public void setYouTubeDataApi(YouTube api) { mYouTubeDataApi = api; } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); pDialog = new ProgressDialog(getActivity()); setRetainInstance(true); if (getArguments() != null) { mPlaylistId = getArguments().getString(ARG_YOUTUBE_PLAYLIST_ID); } } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // set the Picasso debug indicator only for debug builds // Inflate the layout for this fragment View rootView = inflater.inflate(R.layout.youtube_recycler_view_fragment, container, false); mRecyclerView = (RecyclerView) rootView.findViewById(R.id.youtube_recycler_view); // use this setting to improve performance if you know that changes // in content do not change the layout size of the RecyclerView mRecyclerView.setHasFixedSize(true); Resources resources = getResources(); if (resources.getBoolean(R.bool.isTablet)) { // use a staggered grid layout if we're on a large screen device mLayoutManager = new StaggeredGridLayoutManager(resources.getInteger(R.integer.columns), StaggeredGridLayoutManager.VERTICAL); } else { // use a linear layout on phone devices mLayoutManager = new LinearLayoutManager(getActivity()); } mRecyclerView.setLayoutManager(mLayoutManager); return rootView; } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); // if we have a playlist in our retained fragment, use it to populate the UI if (mPlaylist != null) { initAdapter(mPlaylist); } else { // otherwise create an empty playlist mPlaylist = new Playlist(mPlaylistId); // populate an empty UI initAdapter(mPlaylist); // and start fetching the playlist contents pDialog.setMessage("Downloading..."); pDialog.show(); new GetPlaylistAsyncTask(mYouTubeDataApi) { @Override public void onPostExecute(Pair<String, List<Video>> result) { handleGetPlaylistResult(mPlaylist, result); pDialog.hide(); } }.execute(mPlaylist.playlistId, mPlaylist.getNextPageToken()); } } private void initAdapter(final Playlist playlist) { // create the adapter with our playlist and a callback to handle when we reached the last item mAdapter = new PlaylistCardAdapter(playlist, new LastItemReachedListener() { @Override public void onLastItem(int position, String nextPageToken) { new GetPlaylistAsyncTask(mYouTubeDataApi) { @Override public void onPostExecute(Pair<String, List<Video>> result) { handleGetPlaylistResult(playlist, result); } }.execute(playlist.playlistId, playlist.getNextPageToken()); } }); mRecyclerView.setAdapter(mAdapter); } private void handleGetPlaylistResult(Playlist playlist, Pair<String, List<Video>> result) { if (result == null) return; final int positionStart = playlist.size(); playlist.setNextPageToken(result.first); playlist.addAll(result.second); mAdapter.notifyItemRangeInserted(positionStart, result.second.size()); } /** * Interface used by the {@link PlaylistCardAdapter} to inform us that we reached the last item in the list. */ public interface LastItemReachedListener { void onLastItem(int position, String nextPageToken); } }