显示后如何检测每个 RecyclerView 项目

Question

I want to detect each item in my RecylerView after it is displayed to the user.

Basically, I am trying to play a sound on each item after it is loaded on the screen.

But I am not able to detect whenever each item is loaded on the screen! Is there any method I have to call to detect each item rendered

E.g 1st RecyclerView item displayed -> play sound
    2st RecyclerView item displayed -> play sound...

My Adapter class looks like this -

public class AdapterListAnimation extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private List<Multiples> items = new ArrayList<>();

    private Context ctx;
    private OnItemClickListener mOnItemClickListener;
    private int animation_type = 0;
    .........
    .........

I am calling this initComponent() method from onCreated() method. Can you give advice on what should I do to achieve my goal as described above?

private void initComponent() {
    recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    recyclerView.setHasFixedSize(true);
    items = DataGenerator.getPeopleData(this,of,value);
    setAdapter();

    /* MediaPlayer mp=MediaPlayer.create(this, R.raw.sword);
    if (mp.isPlaying()) {
        mp.stop();
        mp.release();
        mp = MediaPlayer.create(this, R.raw.sword);
    } mp.start();*/
}

private void setAdapter() {
    // Set data and list adapter
    mAdapter = new AdapterListAnimation(this, items, animation_type);
    recyclerView.setAdapter(mAdapter);

    // on item list clicked
    mAdapter.setOnItemClickListener(new AdapterListAnimation.OnItemClickListener() {
        @Override
        public void onItemClick(View view, com.math.multiplication.model.Multiples obj, int position) {
            Snackbar.make(parent_view, "Item " + obj.first + " clicked", Snackbar.LENGTH_SHORT).show();
        }
    });
}

Answer 1

you need to override onViewAttachedToWindow and onViewDetachedFromWindow . but for detecting holer type you need getItemViewType() just like that:

public class PostAdapter extends RecyclerView.Adapter {

@Override
public int getItemViewType(int position) {
    switch (types.get(position)){
        case 1:
            return 1;
        case 2:
            return 2;
        default:
            return position;


    }
}
@Override
public void onViewAttachedToWindow(@NonNull RecyclerView.ViewHolder holder) {
    super.onViewAttachedToWindow(holder);
    if (holder.getItemViewType() == 1){
        //play song

    }

}

@Override
public void onViewDetachedFromWindow(@NonNull RecyclerView.ViewHolder holder) {
    super.onViewDetachedFromWindow(holder);
    if (holder.getItemViewType() == 1){
        //pause song

    }
}

Answer 2

You can simply use onViewAttachedToWindow(VH) in your adapter. See https://developer.android.com/reference/android/support/v7/widget/RecyclerView.Adapter.html#onViewAttachedToWindow(VH)

Update:

As you know RecyclerView will be call OnBindViewHolder only once for each item.

RecyclerView will not call this 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.

So you can use onViewAttachedToWindow

(onViewAttachedToWindow) Called when a view created by this adapter has been attached to a window.

This can be used as a reasonable signal that the view is about to be seen by the user. If the adapter previously freed any resources in onViewDetachedFromWindow those resources should be restored here.

You can use it like this:

public class Adapter extends RecyclerView.Adapter<MyViewHolder> {
   
    // rest of your code

   
    @Override
    public void onViewAttachedToWindow(MyViewHolder holder) {
         super.onViewAttachedToWindow(holder);
        // play your sound
    }
}

Hope it helps!

Answer 3

You need to add listener for TTS. Then update your RecyclerView to show right image when speech starts and ends.

I've created a test project to show how it can be implemented. Here you can see how it works. Here is my github repository.

Here is main part of my MainActivity class.

private void initTts() {
    tts = new TextToSpeech(this, this);
    tts.setLanguage(Locale.US);
    tts.setOnUtteranceProgressListener(new MyListener());
}

@Override
public void onInit(int status) {
    playSound(0);
}

private void playSound(int index) {
    HashMap<String, String> hashMap = new HashMap<>();
    hashMap.put(TextToSpeech.Engine.KEY_PARAM_UTTERANCE_ID, String.valueOf(index));
    tts.speak(data.get(index), TextToSpeech.QUEUE_ADD, hashMap);
}

class MyListener extends UtteranceProgressListener {
    @Override
    public void onStart(String utteranceId) {
        int currentIndex = Integer.parseInt(utteranceId);
        mMainAdapter.setCurrentPosition(currentIndex);
        handler.post(new Runnable() {
            @Override
            public void run() {
                mMainAdapter.notifyDataSetChanged();
            }
        });
    }

    @Override
    public void onDone(String utteranceId) {
        int currentIndex = Integer.parseInt(utteranceId);
        mMainAdapter.setCurrentPosition(-1);
        handler.post(new Runnable() {
            @Override
            public void run() {
                mMainAdapter.notifyDataSetChanged();
            }
        });
        if (currentIndex < data.size() - 1) {
            playSound(currentIndex + 1);
        }
    }

    @Override
    public void onError(String utteranceId) {
    }
}

Answer 4

If I understood your problem correctly, you want to play a sound when an item in the RecyclerView is loaded.

Hence I would like to think of a workaround here. You might consider having an item added after the sound for the previous item has been played.

I would like to provide a pseudo code for what I am trying to explain. You might consider using the MediaPlayer.OnCompletionListener for listening if your sound has stopped playing and then add the next item to the RecyclerView and then call notifyDataSetChanged on your adapter to load the next item in your RecyclerView .

Hence you might want the following modification in your adapter first.

// Declare a function in your adapter which adds new item in the RecyclerView
public void addItem(Multiples item) {
    items.add(item);
    notifyItemInserted(items.size());
}

Now in your Activity where you set up the RecyclerView , you need to have the following arrays.

ArrayList<Multiples> allItems = new ArrayList<Multiples>(); // This list will contain all the data
int soundToBePlayed = -1; // Initialize the value with -1
ArrayList<Integer> soundList = getAllSoundsInAList(); 

Modify your functions as follows.

private void initComponent() {
    recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    recyclerView.setHasFixedSize(true);
    allItems = DataGenerator.getPeopleData(this,of,value);
    setAdapter();
}

private void setAdapter() {
    mAdapter = new AdapterListAnimation(this, animation_type); // Do not pass the items list
    recyclerView.setAdapter(mAdapter);

    // .. Your item click listener goes here
}

As the items was removed from the constructor, you need to modify the constructor of your adapter as well. Just remove the variable which takes the items . Because we will be adding elements to the items later.

Then you need to write another function which needs to be called in your onCreate function of your activity after your call your initComponent function. The function should look like the following.

private void addItemInRecyclerViewAndPlaySound() {

    soundToBePlayed++;

    adapter.addItem(allItems.get(soundToBePlayed));
    recyclerView.scrollToPosition(adapter.getItemCount() - 1);

    Integer soundId = soundList.get(soundToBePlayed);

    MediaPlayer mp = MediaPlayer.create(this, soundId);

    if (mp.isPlaying()) {
        mp.stop();
        mp.release();
        mp = MediaPlayer.create(this, soundId);
        mp.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            public void onCompletion(MediaPlayer mp) {
                // Call this function again to add next item
                // and play the next sound at the same time
                if(soundToBePlayed < allItems.size() - 1)
                    addItemInRecyclerViewAndPlaySound();
            }
        });
    }

    mp.start();
}

I have not tested the code, however, I think you get the idea already. This can be implemented gracefully using a interface inside the adapter as well. The imeplemntation technique is your choice.