Java tutorial
/* * Copyright 2017 Andrius Baruckis www.baruckis.com * * 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.baruckis.nanodegree.spotifystreamer.fragments; import android.content.Context; import android.net.Uri; import android.os.Bundle; import android.support.annotation.Nullable; import android.support.v4.app.ListFragment; import android.text.Editable; import android.text.TextWatcher; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.EditText; import android.widget.ListView; import android.widget.Toast; import com.baruckis.nanodegree.spotifystreamer.App; import com.baruckis.nanodegree.spotifystreamer.InfoView; import com.baruckis.nanodegree.spotifystreamer.R; import com.baruckis.nanodegree.spotifystreamer.Utils; import com.baruckis.nanodegree.spotifystreamer.adapters.ArtistArrayAdapter; import com.baruckis.nanodegree.spotifystreamer.models.CustomArtist; import java.util.ArrayList; import kaaes.spotify.webapi.android.SpotifyService; import kaaes.spotify.webapi.android.models.Artist; import kaaes.spotify.webapi.android.models.ArtistsPager; import retrofit.Callback; import retrofit.RetrofitError; import retrofit.client.Response; /** * A list fragment representing a list of Items (Artists). This fragment * also supports tablet devices by allowing list items to be given an * 'activated' state upon selection. This helps indicate which item is * currently being viewed in a {@link ArtistTracksListFragment}. * <p/> * Activities containing this fragment MUST implement the {@link Callbacks} * interface. */ public class ArtistsListFragment extends ListFragment { /** * The serialization (saved instance state) Bundle key representing the * found artists list. */ private static final String STATE_ARTISTS_LIST = "artists_list"; private EditText mSearchEditText; private InfoView mInfoView; private SpotifyService mSpotifyService; private ArtistArrayAdapter mListAdapter; private ArrayList<CustomArtist> mArtistsList; /** * The fragment's current callback object, which is notified of list item * clicks. */ private Callbacks mCallbacks = sDummyCallbacks; /** * A callback interface that all activities containing this fragment must * implement. This mechanism allows activities to be notified of item * selections. */ public interface Callbacks { /** * Callback for when an item has been selected. */ void onItemSelected(String searchText, String artistId, String artistName); /** * Callback for when an text has been changed. */ void onSearchTextChanged(); } /** * A dummy implementation of the {@link Callbacks} interface that does * nothing. Used only when this fragment is not attached to an activity. */ private static Callbacks sDummyCallbacks = new Callbacks() { @Override public void onItemSelected(String searchText, String artistId, String artistName) { } public void onSearchTextChanged() { } }; /** * Mandatory empty constructor for the fragment manager to instantiate the * fragment (e.g. upon screen orientation changes). */ public ArtistsListFragment() { } /* * Events * */ @Override public void onAttach(Context context) { super.onAttach(context); // Context containing this fragment must implement its callbacks. if (!(context instanceof Callbacks)) { throw new IllegalStateException("Context must implement fragment's callbacks."); } mCallbacks = (Callbacks) context; } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mListAdapter = new ArtistArrayAdapter(getActivity(), new ArrayList<CustomArtist>()); setListAdapter(mListAdapter); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = super.onCreateView(inflater, container, savedInstanceState); ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment_artists_list, container, false); mSearchEditText = (EditText) rootView.findViewById(R.id.search_edit_text); mInfoView = (InfoView) rootView.findViewById(R.id.info_view); ViewGroup contentLayout = (ViewGroup) rootView.findViewById(R.id.content_layout); contentLayout.addView(view); // after add info view goes behind and becomes unclickable, so that's why it is moved to front. mInfoView.bringToFront(); return rootView; } @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); if (savedInstanceState != null) { // Check if error message should be shown, and if yes than don't continue on other checks and return; if (savedInstanceState.containsKey(InfoView.STATE_IS_ERROR) && savedInstanceState.getBoolean(InfoView.STATE_IS_ERROR)) { showError(); return; } // If the was no error than get artists list, which can be empty or filled with data. // If it is empty than there was no such artists based on search and message for the user will be showed. if (savedInstanceState.containsKey(STATE_ARTISTS_LIST)) { // restore the previously serialized artists list. mArtistsList = savedInstanceState.getParcelableArrayList(STATE_ARTISTS_LIST); showArtists(); return; } } // if there was no error or no artist list saved (is null), that means that initial message should be shown mInfoView.showEmpty(getString(R.string.info_msg_empty_artists_list_init)); resetActionBar(); } @Override public void onActivityCreated(@Nullable Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); mSpotifyService = ((App) getActivity().getApplication()).getSpotifyService(); } @Override public void onResume() { super.onResume(); mSearchEditText.addTextChangedListener(mTextWatcher); } @Override public void onPause() { mSearchEditText.removeTextChangedListener(mTextWatcher); super.onPause(); } @Override public void onListItemClick(ListView listView, View view, int position, long id) { super.onListItemClick(listView, view, position, id); // Notify the active callbacks interface (the activity, if the // fragment is attached to one) that an item has been selected. CustomArtist clickedArtist = mListAdapter.getItem(position); mCallbacks.onItemSelected(mSearchEditText.getText().toString(), clickedArtist.getId(), clickedArtist.getName()); } @Override public void onSaveInstanceState(Bundle outState) { // Check if error message is shown and save state if it is. if (mInfoView != null && mInfoView.getIsError()) { outState.putBoolean(InfoView.STATE_IS_ERROR, mInfoView.getIsError()); // If artists list is empty or filled with data than save it. // If it is null, means initial search message for user is shown. } else if (mArtistsList != null) { // Serialize and persist found artists list. outState.putParcelableArrayList(STATE_ARTISTS_LIST, mArtistsList); } super.onSaveInstanceState(outState); } @Override public void onDetach() { super.onDetach(); // Reset the active callbacks interface to the dummy implementation. mCallbacks = sDummyCallbacks; } /* * Objects * */ private TextWatcher mTextWatcher = new TextWatcher() { Boolean block = false; @Override public void beforeTextChanged(CharSequence s, int start, int count, int after) { block = count == after; } @Override public void onTextChanged(CharSequence s, int start, int before, int count) { } @Override public void afterTextChanged(Editable s) { if (block || mSpotifyService == null) return; getListView().clearChoices(); mListAdapter.clear(); mInfoView.hide(); resetActionBar(); mCallbacks.onSearchTextChanged(); if (s.toString().length() == 0) { mArtistsList = null; mInfoView.showEmpty(getString(R.string.info_msg_empty_artists_list_init)); } else { mSpotifyService.searchArtists(s.toString(), searchArtistsCallback); } } }; private Callback<ArtistsPager> searchArtistsCallback = new Callback<ArtistsPager>() { @Override public void success(ArtistsPager artistsPager, Response response) { /* Block filling list with new artists if text entered inside search box is different * compared to query text for which data response came back. * This can happen if user change search text inside search box too fast. * */ String searchString = mSearchEditText.getText().toString(); Uri uri = Uri.parse(response.getUrl()); String queryString = uri.getQueryParameter("q"); if (!searchString.equals(queryString)) return; mArtistsList = new ArrayList<CustomArtist>(); // if OK than fill adapter with new data for (Artist artist : artistsPager.artists.items) { CustomArtist customArtist = new CustomArtist(); customArtist.setId(artist.id); customArtist.setName(artist.name); customArtist.setImageUrl(Utils.getImageSmallUrl(artist.images)); mArtistsList.add(customArtist); } showArtists(); } @Override public void failure(RetrofitError error) { Toast.makeText(getContext(), error.getLocalizedMessage(), Toast.LENGTH_LONG).show(); Log.e(ArtistsListFragment.class.getSimpleName(), error.getMessage()); showError(); } }; /* * Methods * */ /** * Turns on activate-on-click mode. When this mode is on, list items will be * given the 'activated' state when touched. */ public void setActivateOnItemClick(boolean activateOnItemClick) { // When setting CHOICE_MODE_SINGLE, ListView will automatically // give items the 'activated' state when touched. getListView().setChoiceMode(activateOnItemClick ? ListView.CHOICE_MODE_SINGLE : ListView.CHOICE_MODE_NONE); } public void restoreSearchEditText(String text) { if (text == null) return; mSearchEditText.addTextChangedListener(mTextWatcher); mSearchEditText.setText(text); // set the EditText cursor to the end of its text mSearchEditText.setSelection(mSearchEditText.getText().length()); } private void resetActionBar() { Utils.setActionBar(getActivity(), getString(R.string.app_name), null); } private void showArtists() { mInfoView.setIsError(false); if (mArtistsList.isEmpty()) { mInfoView.showEmpty(getString(R.string.info_msg_empty_artists_list)); return; } Utils.fillAdapter(mListAdapter, mArtistsList); } private void showError() { // Show error message with ability to for user to restart the call by pressing a button mInfoView.showError(getString(R.string.info_msg_error), new View.OnClickListener() { @Override public void onClick(View v) { mInfoView.hide(); mSpotifyService.searchArtists(mSearchEditText.getText().toString(), searchArtistsCallback); } }); } }