如何刷新recyclerview？

Question

我用碎片制作了一个mediaplayer应用程序；歌曲、专辑、艺术家、流派、播放列表

这是我的一个片段中的代码，我将以艺术家为例

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View rootView = inflater.inflate(R.layout.fragment_tab3, container, false);
    recyclerViewArtists = rootView.findViewById(R.id.recyclerViewArtists);

    initRecyclerView();

    return rootView;
}

private void initRecyclerView(){
    items = Main.songs.getArtists();

    if ((items != null) && (! items.isEmpty())) {
        adapter = new Adapter(getContext(), items);
        recyclerViewArtists.setLayoutManager(new LinearLayoutManager(getActivity()));
        recyclerViewArtists.setHasFixedSize(true);
        recyclerViewArtists.setAdapter(adapter);
        Log.i(TAG, "Artists found in list!");

    recyclerViewArtists.addOnItemTouchListener(new OnItemClickListeners(getContext(), new OnItemClickListeners.OnItemClickListener() {
        @TargetApi(Build.VERSION_CODES.O)
        @Override
        public void onItemClick(View view, int position) {
            Toast.makeText(getContext(), "You Clicked position: " + position + " " + items.get(position) , Toast.LENGTH_SHORT).show();
            if (! Main.songs.isInitialized()){
                return;
            }
            String selectedArtist = items.get(position);

            Main.musicList = Main.songs.getSongsByArtist(selectedArtist);
            Intent intent = new Intent(getContext(), ListSongsActivity.class);
            intent.putExtra("title", selectedArtist);
            startActivity(intent);
        }
    }));

    }else{
        Log.i(TAG, "No artists found in list!");
    }
}

在我的initRecyClaire View（）方法中，我有一个名为“项目”的数组列表，其中包含歌曲艺术家。Main.songs.get艺术家-

现在，当用户点击一个艺术家时，另一个活动将启动ListSong sActivity.java

这是类中的代码ListSong sActivity.java

 @Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.list_songs_layout);

    //Holds all the songs in a scrollable list.
    recyclerViewListSongs = findViewById(R.id.recyclerViewListSongs);
    Intent intent = getIntent();
    Bundle bundle = intent.getExtras();

    // Connects the song list to an adapter
    // (thing that creates several Layouts from the song list)
    if ((Main.musicList != null) && (!Main.musicList.isEmpty())) {
        allSongsAdapter = new AllSongsAdapter(this, Main.musicList);
        recyclerViewListSongs.setLayoutManager(new LinearLayoutManager(getApplicationContext()));
        recyclerViewListSongs.setHasFixedSize(true);
        recyclerViewListSongs.setAdapter(allSongsAdapter);
        allSongsAdapter.notifyDataSetChanged();
    }

    mToolbar = findViewById(R.id.mToolbar);
    setSupportActionBar(mToolbar);

    if ((getSupportActionBar() != null) && (bundle != null)) {
        getSupportActionBar().setTitle((String) bundle.get("title"));
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_home_up);
    }

    recyclerViewListSongs.addOnItemTouchListener(new OnItemClickListeners(getApplicationContext(), new OnItemClickListeners.OnItemClickListener() {
        @Override
        public void onItemClick(View view, int position) {
            playAudio(position);
            Toast.makeText(getApplicationContext(), "You Clicked position: " + position + Main.musicList.get(position).getData(), Toast.LENGTH_SHORT).show();
        }
    }));
}

private void playAudio(int songIndex) {
    //Check if service is active
    if (!MediaPlayerService.musicBound) {
        StorageUtil storageUtil = new StorageUtil(this);
        storageUtil.storeSong(Main.musicList);
        storageUtil.storeSongIndex(songIndex);

        Intent playerIntent = new Intent(this, MediaPlayerService.class);
        startService(playerIntent);
        bindService(playerIntent, Main.musicConnection, Context.BIND_AUTO_CREATE);
    } else {
        //Store new songIndex in mSharedPreferences
        StorageUtil storageUtil = new StorageUtil(this);
        storageUtil.storeSong(Main.musicList);
        storageUtil.storeSongIndex(songIndex);

        //MediaService is active
        //Send media with BroadcastReceiver
        Intent broadCastReceiverIntent = new Intent(broadCast_PlAY_NEW_SONG);
        sendBroadcast(broadCastReceiverIntent);
    }
}

在这个类中，我存储songList和songIndex，其中songlist=保存歌曲信息的数组列表，songindex=单击位置

public class StorageUtil {
private final String STORAGE = "com.vince_mp3player.STORAGE";
private SharedPreferences mSharedPreferences;
private Context context;
private SharedPreferences.Editor mEditor;



public StorageUtil(Context context){
    this.context = context;
}

public void storeSong(List<Song> list){
    mSharedPreferences = context.getSharedPreferences(STORAGE, Context.MODE_PRIVATE);
    mEditor = mSharedPreferences.edit();
    Gson gson = new Gson();
    String json = gson.toJson(list);
    mEditor.putString("songList", json);
    mEditor.apply();
}

public ArrayList<Song> getSongs(){
    mSharedPreferences = context.getSharedPreferences(STORAGE, Context.MODE_PRIVATE);
    Gson gson = new Gson();
    String json = mSharedPreferences.getString("songList", null);
    Type type = new TypeToken<List<Song>>(){
    }.getType();
    return gson.fromJson(json, type);
}

public void storeSongIndex(int index) {
    mSharedPreferences = context.getSharedPreferences(STORAGE, Context.MODE_PRIVATE);
    mEditor = mSharedPreferences.edit();
    mEditor.putInt("songIndex", index);
    mEditor.apply();
}

public int loadSongIndex() {
    mSharedPreferences = context.getSharedPreferences(STORAGE, Context.MODE_PRIVATE);
    return mSharedPreferences.getInt("songIndex", -1);//return -1 if no data found
}

public void clearCachedAudioPlaylist() {
    mSharedPreferences = context.getSharedPreferences(STORAGE, Context.MODE_PRIVATE);
    mEditor = mSharedPreferences.edit();
    mEditor.clear();
    mEditor.apply();
}
 }

我的问题开始了，假设我们从名单中选择艺术家甲-

然后当我按后退按钮返回，选择艺术家B并点击其中一首歌曲时，它仍然播放艺术家A的歌曲。

即使在我第一个显示所有歌曲的片段中，当我点击一首歌曲时，它也只播放我在“艺术家”选项卡中选择的艺术家的歌曲，当我在3点结束时选择另一首歌曲时，它会崩溃。

当我点击后退按钮时，如何更新我的recyclerviews？

如果你不明白我的帖子，我会给dropbox，github添加代码，这样你就可以自己测试了。

提前谢谢，

文斯

Answer 1

看起来，当您将广播发送到MediaPlayerService时，songList变量仍然设置为创建服务时的初始歌曲。我首先在MediaPlayerService的NewSongBroadcastReceiver中更新了songList，使它能够工作。java：

private BroadcastReceiver NewSongBroadCastReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        songList = new StorageUtil(getApplicationContext()).getSongs();
        songIndex = new StorageUtil(getApplicationContext()).loadSongIndex();
        if (songIndex != -1 && songIndex < songList.size()){
            activeSong = songList.get(songIndex);
        }else{
            stopSelf();
        }
        stopSong();
        mediaPlayer.reset();
        initMediaPlayer();
        updateMetaData();
        NotificationBuilder(PlaybackStatus.PLAYING);
    }
};