Java tutorial
/*** Copyright (c) 2008-2016 CommonsWare, LLC 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 http://www.apache.org/licenses/LICENSE-2.0. 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. Covered in detail in the book _The Busy Coder's Guide to Android Development_ https://commonsware.com/Android */ package com.commonsware.android.recyclerview.videotable; import android.Manifest; import android.app.LoaderManager; import android.content.CursorLoader; import android.content.Loader; import android.content.pm.PackageManager; import android.database.Cursor; import android.os.Bundle; import android.provider.MediaStore; import android.support.v4.app.ActivityCompat; import android.support.v4.content.ContextCompat; import android.support.v7.widget.GridLayoutManager; import android.support.v7.widget.RecyclerView; import android.view.ViewGroup; public class MainActivity extends RecyclerViewActivity implements LoaderManager.LoaderCallbacks<Cursor> { private static final int[] COLUMN_WEIGHTS = { 1, 4, 1 }; private static final String STATE_IN_PERMISSION = "inPermission"; private static final int REQUEST_PERMS = 137; private boolean isInPermission = false; @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); ColumnWeightSpanSizeLookup spanSizer = new ColumnWeightSpanSizeLookup(COLUMN_WEIGHTS); GridLayoutManager mgr = new GridLayoutManager(this, spanSizer.getTotalSpans()); mgr.setSpanSizeLookup(spanSizer); setLayoutManager(mgr); setAdapter(new VideoAdapter()); if (icicle != null) { isInPermission = icicle.getBoolean(STATE_IN_PERMISSION, false); } if (hasFilesPermission()) { loadVideos(); } else if (!isInPermission) { isInPermission = true; ActivityCompat.requestPermissions(this, new String[] { Manifest.permission.READ_EXTERNAL_STORAGE }, REQUEST_PERMS); } } @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putBoolean(STATE_IN_PERMISSION, isInPermission); } @Override public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) { isInPermission = false; if (requestCode == REQUEST_PERMS) { if (hasFilesPermission()) { loadVideos(); } else { finish(); // denied permission, so we're done } } } @Override public Loader<Cursor> onCreateLoader(int arg0, Bundle arg1) { return (new CursorLoader(this, MediaStore.Video.Media.EXTERNAL_CONTENT_URI, null, null, null, MediaStore.Video.Media.TITLE)); } @Override public void onLoadFinished(Loader<Cursor> loader, Cursor c) { ((VideoAdapter) getAdapter()).setVideos(c); } @Override public void onLoaderReset(Loader<Cursor> loader) { ((VideoAdapter) getAdapter()).setVideos(null); } private boolean hasFilesPermission() { return (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED); } private void loadVideos() { getLoaderManager().initLoader(0, null, this); } class VideoAdapter extends RecyclerView.Adapter<BaseVideoController> { Cursor videos = null; @Override public BaseVideoController onCreateViewHolder(ViewGroup parent, int viewType) { BaseVideoController result = null; switch (viewType) { case 0: result = new VideoThumbnailController( getLayoutInflater().inflate(R.layout.thumbnail, parent, false)); break; case 1: int cursorColumn = videos.getColumnIndex(MediaStore.Video.VideoColumns.DISPLAY_NAME); result = new VideoTextController(getLayoutInflater().inflate(R.layout.label, parent, false), android.R.id.text1, cursorColumn); break; case 2: cursorColumn = videos.getColumnIndex(MediaStore.Video.VideoColumns.DURATION); result = new VideoTextController(getLayoutInflater().inflate(R.layout.label, parent, false), android.R.id.text1, cursorColumn); break; } return (result); } @Override public void onBindViewHolder(BaseVideoController holder, int position) { videos.moveToPosition(position / 3); holder.bindModel(videos); } void setVideos(Cursor videos) { this.videos = videos; notifyDataSetChanged(); } @Override public int getItemCount() { if (videos == null) { return (0); } return (videos.getCount() * 3); } @Override public int getItemViewType(int position) { return (position % 3); } } }