Question

我们正在为一个项目制作一个Android的MusicPlayer。我们有3个标签 - 歌曲（显示手机上的所有歌曲），正在播放（应显示当前排队的歌曲）和播放列表。

排队的歌曲不会出现在NowPlayingFragment中。我为我目前排队的歌曲实施了RecyclerView。歌曲通过SongsRecyclerAdapter（处理＆＃34;歌曲＆＃34;标签中的列表）排队。我在MusicProvider类中使用静态addToQueue（）方法，它将歌曲添加到List currentQueue（在同一个类中）并且恰好在来自适配器的NotifyDataSetChanged（）之后用于入队列表。适配器本身对其项目使用相同的List currentQueue。这是我的enqueueAdapter

public class NowPlayingRecyclerAdapter  extends RecyclerView.Adapter<NowPlayingRecyclerAdapter.ViewHolder>{
private Context context;
public List<MediaMetadataCompat> mSongs;
private LayoutInflater inflater;
public NowPlayingRecyclerAdapter(Context context,List<MediaMetadataCompat> songs){
    this.context = context;
    this.mSongs = songs;
    this.inflater = LayoutInflater.from(context);
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = inflater.inflate(R.layout.song_item,parent,false);
    return new ViewHolder(view);
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    MediaMetadataCompat currentSong = mSongs.get(position);
    holder.setData(currentSong,position);
    holder.setListeners();
}

private void removeSongFromQueue(int position) {
    mSongs.remove(position);
    notifyItemRemoved(position);
    notifyItemRangeChanged(position,getItemCount());
}

@Override
public int getItemCount() {
    return mSongs.size();
}

class ViewHolder extends RecyclerView.ViewHolder implements  View.OnClickListener {

    LinearLayout item;
    TextView title;
    TextView artist;
    ImageView deleteIcon;
    int position;
    MediaMetadataCompat current;
    ImageView dotsIcon;

    private ViewHolder(View itemView) {
        super(itemView);
        this.item = (LinearLayout) itemView.findViewById(R.id.song_item);
        this.artist = (TextView) itemView.findViewById(R.id.artist);
        this.title = (TextView) itemView.findViewById(R.id.title);
        this.deleteIcon = (ImageView) itemView.findViewById(R.id.img_delete);
        this.dotsIcon = (ImageView) itemView.findViewById(R.id.img_dots);
        dotsIcon.setVisibility(View.GONE);
    }

    private void setData(MediaMetadataCompat currentSong, int position) {
        this.current = currentSong;
        this.title.setText(currentSong.getDescription().getTitle());
        this.artist.setText(currentSong.getDescription().getSubtitle());
        this.position = position;
    }

    private void setListeners() {
        deleteIcon.setOnClickListener(ViewHolder.this);
    }

    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.img_delete) {
            removeSongFromQueue(position);
            //removeSongFromPlaylistFile();
        }
    }

}

这是我的NowPlaingFragment（用于入队）

public class NowPlayingFragment extends Fragment {

public static NowPlayingRecyclerAdapter adapter;
private Context context;
public static List<MediaMetadataCompat> songs;


@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.now_playing_fragment, container, false);

    context = getActivity();
    songs = MusicProvider.getCurrentQueue();
    context = getActivity();

    setUpRecyclerView(view);

    return view;
}

private void setUpRecyclerView(View view) {
    RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.recycler_view_queue);
    recyclerView.setHasFixedSize(true);
    adapter = new NowPlayingRecyclerAdapter(context,songs);
    //adapter = new SongsRecyclerAdapter(view.getContext(),songs,true);
    recyclerView.setAdapter(adapter);

    LinearLayoutManager myLinearLayoutManager = new LinearLayoutManager(view.getContext());
    myLinearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
    recyclerView.setLayoutManager(myLinearLayoutManager);
    recyclerView.addItemDecoration(new DividerItemDecoration(context, myLinearLayoutManager.getOrientation()));
}

这就是我在一个点击收听器中排队的歌曲

    MusicProvider.addToQueue(songs.get(getAdapterPosition())
                                        .getMediaId());
    NowPlayingRecyclerAdapter myAdapter = NowPlayingFragment.adapter;

                                myAdapter.notifyDataSetChanged();

MusicProvider类中的重要内容：

    public static void addToQueue(String mediaId) {
    if (currentQueue == null)
        currentQueue = new ArrayList<>();
    currentQueue.add(getSong(mediaId));
}
 public static List<MediaMetadataCompat> getCurrentQueue() {
    return currentQueue != null ? currentQueue : Collections.<MediaMetadataCompat>emptyList();
}

Answer 1

从适配器和片段内的歌曲中删除静态。 MediaProvider也充满了静态。您应该通过实例名称引用或创建单例并通过getInstance引用。

Answer 2

只需致电

 notifyDataSetChanged();
 or 
 notifyItemChanged(position);

RecyclerView无法可视化/更新

2 个答案: