RecyclerView滚动时随机更改位置

Question

I have made a chat app where I have used a RecyclerView . Messages can be either text messages or audio messages. Everything is working fine except when I change the timer text on the TextView (for audio player layout I have made) , of how long has the song been played. I do this in a Runnable . But when I scroll the RecyclerView , the timer TextView changes text at random position.

Here is how I am changing the TextView text:

public void updateTimer(final int position) {
    View view = mRecyclerViewChat.getLayoutManager().findViewByPosition(position);
    timer = (TextView) view.findViewById(R.id.timer);

     r = new Runnable() {
        public void run() {
            int currentDuration;
            if (player.isPlaying()) {
                currentDuration = player.getCurrentPosition();
                timer.setText("" + milliSecondsToTimer((long) currentDuration));
                timer.postDelayed(this, 1000);
            } else {
                timer.removeCallbacks(this);
            }
        }
    };

    timer.post(r);
}

Here position is the position value I am getting from the onBindViewHolder .

EDIT

Here is the onBindViewHolder

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    if (TextUtils.equals(mChats.get(position).senderUid,
            FirebaseAuth.getInstance().getCurrentUser().getUid())) {
        if (mChats.get(position).mediaUrlLocal == null) {
            configureMyChatViewHolder((MyChatViewHolder) holder, position);
        } else {
            configureMyChatMediaViewHolder((MyChatMediaViewHolder) holder, position);
        }
    } else {
        if (mChats.get(position).mediaUrlLocal == null) {
            configureOtherChatViewHolder((OtherChatViewHolder) holder, position);
        } else {
            configureOtherChatMediaViewHolder((OtherChatMediaViewHolder) holder, position);
        }
    }
}

and here is the playMedia method which is called from configureMyChatMediaViewHolder method:

private void playMyMedia(final MyChatMediaViewHolder myChatViewHolder, final Chat chat, final int position) {
    MediaMetadataRetriever metaRetriever = new MediaMetadataRetriever();
    metaRetriever.setDataSource(chat.mediaUrlLocal);

    String duration =
            metaRetriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION);
    long dur = Long.parseLong(duration);
    String seconds = String.valueOf((dur % 60000) / 1000);

    String minutes = String.valueOf(dur / 60000);
    String out = minutes + ":" + seconds;

    myChatViewHolder.timer.setText(out);

    if (chat.isPlay) {
        myChatViewHolder.play.setVisibility(View.GONE);
        myChatViewHolder.pause.setVisibility(View.VISIBLE);
    } else {
        myChatViewHolder.play.setVisibility(View.VISIBLE);
        myChatViewHolder.pause.setVisibility(View.GONE);
    }

    myChatViewHolder.play.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            chat.isPlay = !chat.isPlay;
            if (previousChat != position && previousChat != -1) {
                previousChatObj = mChats.get(previousChat);
            }
            previousChat = position;
            myChatViewHolder.play.setVisibility(View.GONE);
            myChatViewHolder.pause.setVisibility(View.VISIBLE);
            callback.onPlayClickListener(chat, previousChatObj, position);
        }
    });

    myChatViewHolder.pause.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            chat.isPlay = !chat.isPlay;
            myChatViewHolder.play.setVisibility(View.VISIBLE);
            myChatViewHolder.pause.setVisibility(View.GONE);
            callback.onPauseClickListener(chat, position);
        }
    });
}

I have only one media player instance in the fragment from which the adapter for chat is set.

Answer 1

Recycler view is re-using the views that are not currently visible. So if your audio player starts updating one Text View , when you scroll that textview is the same reference but with different text ( song ), but your runnable instance is still active and doing its job to update the Text View with same reference.

1. You should create a custom Runnable class which will hold a position value and will be only responsible for the TextView it should update.

2. Other approach ( less efficient ) is to use ListView and not to re-use the cells to create new one for each item. This will cause performance issues

If you can send some code i would like to help you out.

*** EDITED ****

Here is some code part that can make things more clear

@Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        holder.songDurationView.setTag(position);
        //TODO: implement some more logic here and start the MusicSongRunnable
    }



class MusicSongRunnable implements Runnable {

    int positionOfSong;
    TextView textView;

    public MusicSongRunnable(int positionOfSong, TextView textView) {
        this.positionOfSong = positionOfSong;
        this.textView = textView;
    }

    @Override
    public void run() {
        if (player.isPlaying() && positionOfSong == textView.getTag()) {
        //TODO: update the song;
    }
}

Answer 2

It is not clear where you call updateTimer , but I assume that you call it from within callback.onPlayClickListener(..) and callback.onPauseClickListener(..) .

First , do not pass it the position you've got as a parameter in click listeners, but as documentation states you should use ViewHolder.getAdapterPosition() method. Note, that when you use the value of the position you should also check that it is different from RecuclerView.NO_POSITION each time and only then use it. Make your position parameter not final in all methods. It will prevent you from making mistakes. Each time you want to use position in click listeners use myChatViewHolder.getAdapterPosition()

Second , since you cache position value in the Runnable anyway, this is probably not enough. So you should pass myChatViewHolder.timer as a parameter to updateTimer and get rid of first two lines. In the end you call updateTimer like this:

updateTimer(myChatViewHolder.timer);

and your 'updateTimer' now is:

public void updateTimer(final TextView timer) {

    r = new Runnable() {
        public void run() {
            int currentDuration;
            if (player.isPlaying()) {
                currentDuration = player.getCurrentPosition();
                timer.setText("" + milliSecondsToTimer((long) currentDuration));
                timer.postDelayed(this, 1000);
            } else {
                timer.removeCallbacks(this);
            }
        }
    };

    timer.post(r);
}

More from the documentation on this matter:

RecyclerView will not call onBindViewHolder() method again if the position of the item changes in the data set unless the item itself is invalidated or the new position cannot be determined. For this reason, you should only use the position parameter while acquiring the related data item inside this method and should not keep a copy of it.