Java tutorial
/* * Copyright 2017 Armann David Sigurdsson * * 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. */ package com.armannds.eldgos.katla.popularmovies.ui; import android.content.Context; import android.content.Intent; import android.net.ConnectivityManager; import android.net.NetworkInfo; import android.os.Bundle; import android.support.v4.app.LoaderManager; import android.support.v4.content.AsyncTaskLoader; import android.support.v4.content.Loader; import android.support.v7.app.AppCompatActivity; import android.support.v7.widget.GridLayoutManager; import android.support.v7.widget.RecyclerView; import android.util.DisplayMetrics; import android.util.Log; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.widget.ProgressBar; import android.widget.TextView; import com.armannds.eldgos.katla.popularmovies.PopularMoviesApplication; import com.armannds.eldgos.katla.popularmovies.R; import com.armannds.eldgos.katla.popularmovies.api.TheMovieDbResponse; import com.armannds.eldgos.katla.popularmovies.api.TheMovieDbService; import com.armannds.eldgos.katla.popularmovies.data.Movie; import com.armannds.eldgos.katla.popularmovies.ui.detail.MovieDetailsActivity; import com.armannds.eldgos.katla.popularmovies.utils.CollectionUtils; import org.parceler.Parcels; import java.io.IOException; import java.util.ArrayList; import java.util.List; import javax.inject.Inject; import butterknife.BindString; import butterknife.BindView; import butterknife.ButterKnife; import retrofit2.Call; public class MainActivity extends AppCompatActivity implements MoviesAdapter.MoviesAdapterOnClickHandler, LoaderManager.LoaderCallbacks<List<Movie>> { private static final String TAG = MainActivity.class.getSimpleName(); private static final int MOVIE_LOADER = 17; @BindString(R.string.movies_key) String mMoviesKey; @BindString(R.string.title_key) String mTitleKey; @BindView(R.id.rv_movies) RecyclerView mRecyclerView; @BindView(R.id.tv_error_message_display) TextView mErrorMessageDisplay; @BindView(R.id.pb_loading_indicator) ProgressBar mLoadingIndicator; private MoviesAdapter mMoviesAdapter; private int mMovieFilter; @Inject TheMovieDbService theMovieDbService; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ButterKnife.bind(this); ((PopularMoviesApplication) getApplication()).getNetworkComponent().inject(this); Context context = this; MoviesAdapter.MoviesAdapterOnClickHandler clickHandler = this; mMoviesAdapter = new MoviesAdapter(context, clickHandler); mRecyclerView.setAdapter(mMoviesAdapter); mRecyclerView.setLayoutManager(new GridLayoutManager(this, calculateNoOfColumns())); mRecyclerView.setHasFixedSize(true); if (isSavedInstanceStateValid(savedInstanceState)) { List<Movie> movies = Parcels.unwrap(savedInstanceState.getParcelable(mMoviesKey)); mMoviesAdapter.setMovies(movies); String title = savedInstanceState.getString(mTitleKey); setTitle(title); } else { if (isOnline()) { loadMovies(R.string.popular); } else { showErrorMessage(); } } } private int calculateNoOfColumns() { DisplayMetrics displayMetrics = getResources().getDisplayMetrics(); float dpWidth = displayMetrics.widthPixels / displayMetrics.density; return (int) (dpWidth / 180); } private boolean isSavedInstanceStateValid(Bundle savedInstanceState) { return savedInstanceState != null && savedInstanceState.containsKey(mMoviesKey) && savedInstanceState.containsKey(mTitleKey); } private boolean isOnline() { ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); NetworkInfo netInfo = cm.getActiveNetworkInfo(); return netInfo != null && netInfo.isConnectedOrConnecting(); } @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); if (CollectionUtils.isNotEmpty(mMoviesAdapter.getMovies())) { ArrayList<Movie> movies = new ArrayList<>(mMoviesAdapter.getMovies()); outState.putParcelable(mMoviesKey, Parcels.wrap(movies)); } outState.putString(mTitleKey, getTitle().toString()); } private void loadMovies(int movieFilter) { showMoviesGrid(); mMovieFilter = movieFilter; LoaderManager loaderManager = getSupportLoaderManager(); Loader<List<Movie>> movieLoader = loaderManager.getLoader(MOVIE_LOADER); if (movieLoader == null) { loaderManager.initLoader(MOVIE_LOADER, null, this); } else { loaderManager.restartLoader(MOVIE_LOADER, null, this); } setTitle(movieFilter); } @Override public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.movie_filter, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { int id = item.getItemId(); if (id == R.id.action_popular) { loadMovies(R.string.popular); return true; } if (id == R.id.action_top_rated) { loadMovies(R.string.top_rated); return true; } return super.onOptionsItemSelected(item); } @Override public void onClick(Movie movie) { Context context = this; Class destinationClass = MovieDetailsActivity.class; Intent intentToStartDetailsActivity = new Intent(context, destinationClass); intentToStartDetailsActivity.putExtra(Movie.EXTRA, Parcels.wrap(movie)); startActivity(intentToStartDetailsActivity); } private void showErrorMessage() { mRecyclerView.setVisibility(View.INVISIBLE); mErrorMessageDisplay.setVisibility(View.VISIBLE); } private void showMoviesGrid() { mRecyclerView.setVisibility(View.VISIBLE); mErrorMessageDisplay.setVisibility(View.INVISIBLE); } @Override public Loader<List<Movie>> onCreateLoader(int id, Bundle args) { return new AsyncTaskLoader<List<Movie>>(this) { List<Movie> mMovies; @Override public void onStartLoading() { if (mMovies != null) { deliverResult(mMovies); } else { mLoadingIndicator.setVisibility(View.VISIBLE); forceLoad(); } } @Override public void deliverResult(List<Movie> data) { mMovies = data; super.deliverResult(data); } @Override public List<Movie> loadInBackground() { Call<TheMovieDbResponse> theMovieDbResponse; if (mMovieFilter == R.string.top_rated) { theMovieDbResponse = theMovieDbService.getTopRatedMovies(); } else { theMovieDbResponse = theMovieDbService.getPopularMovies(); } List<Movie> movies = null; if (theMovieDbResponse != null) { try { movies = theMovieDbResponse.execute().body().getResults(); } catch (IOException e) { Log.e(TAG, "Error retrieving movies!"); } } return movies; } }; } @Override public void onLoadFinished(Loader<List<Movie>> loader, List<Movie> data) { mLoadingIndicator.setVisibility(View.INVISIBLE); if (data != null) { showMoviesGrid(); mMoviesAdapter.setMovies(data); } else { showErrorMessage(); } } @Override public void onLoaderReset(Loader<List<Movie>> loader) { } }