Brtdku

Update:
I decide to create a github repo with this issue to anyone can try to reproduce it and try to fix it.
https://github.com/LolusKekus/NestsedRecyclerScrollItselfChallenge

I have vertical recycler with a bunch of nested horisontal recyclers.
When i'm scrolling over vertical recycler, nested recyclers scroll themself without any reason.

It's looks like this.
Before scroll, let's imagine that selector on 31:

_____________

|31 32 33 34|

|41 42 43 44|

|51 52 53 54|

_____________

now press up on dpad (i'm working on android tv app):

_____________

|24 25 26 27|

|31 32 33 34|

|41 42 43 44|

_____________

Hidden recyclerview appears, binds and scrolls up to 24 element. But it mustn't be! The selected item must be 21! And so on until the top of vertical recycler... 14... 04...

I'm noticed, nested recycler scrolls just to last visible item on it.

this behavior appears after "com.android.support:recyclerview-v7:24.2.1"

Now i'm using "com.android.support:recyclerview-v7:27.1.1" and faced with this issue.

Activity:

public class MainActivity extends AppCompatActivity {

    List<String> hDataset;

    List<Integer> vDataset;



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        context = this;

        hDataset = new ArrayList<>();

        for (int i=0; i<hItemsCount; i++) {

            hDataset.add(String.format("lolKek Cheburek %d", i));

        }



        vDataset = new ArrayList<>();

        for (int i=0; i<vItemsCount; i++) {

            vDataset.add(i);

        }



        vRecyclerView = findViewById(R.id.vRecyclerView);

        vRecyclerView.setHasFixedSize(true);



        LinearLayoutManager layoutManager = new LinearLayoutManager(this);

        layoutManager.setOrientation(LinearLayoutManager.VERTICAL);

        vRecyclerView.setLayoutManager(layoutManager);

        vRecyclerView.setAdapter(new VAdapter(vDataset, hDataset, context));

}

Vertical adapter:

public class VAdapter extends RecyclerView.Adapter<VAdapter.MyVertHolder>() {

    private List<String> hDataset;

    private Context context;



    public VAdapter(List<String> hDataset, List<String> vDataset, Context context) {

       this.hDataset = hDataset;

       this.vDataset = vDataset;

       this.context = context;

    }



    public static class MyVertHolder extends RecyclerView.ViewHolder {

        RecyclerView hRecyclerView;



        public MyVertHolder(final View itemView) {

            super(itemView);

            hRecyclerView = itemView.findViewById(R.id.hRecyclerView);

        }



        public void setAdapter(HAdapter adapter) {

            hRecyclerView.setAdapter(adapter);

        }



        public void setLayoutManager(LinearLayoutManager layoutManager) {

            hRecyclerView.setLayoutManager(layoutManager);

        }

    }



    @NonNull

    @Override

    public MyVertHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        View itemView = LayoutInflater

            .from(parent.getContext())

            .inflate(R.layout.v_item_view, parent, false);



        MyVertHolder holder = new MyVertHolder(itemView);

        holder.setAdapter(new HAdapter(hDataset));

        holder.setLayoutManager(new LinearLayoutManage(context, LinearLayoutManager.HORIZONTAL, false));

        return holder;

    }



    @Override

    public void onBindViewHolder(final @NonNull MyVertHolder holder, int position) {

        ... some bindings

    }

}

Horisontal adapter:

class HAdapter extends RecyclerView.Adapter<HAdapter.MyHolder> {

    private List<String> dataset;

    public HAdapter(List<String> dataset) {

        this.dataset = dataset;

    }



    public static class MyHolder extends RecyclerView.ViewHolder {



        private TextView tvItemText;



        public MyHolder(FrameLayout itemView) {

            super(itemView);

            tvItemText = itemView.findViewById(R.id.tvItemText);

        }

    }



@Override

    public MyHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        FrameLayout itemView = (FrameLayout) LayoutInflater

.from(parent.getContext()).inflate(R.layout.item_view, parent, false);

        return new MyHolder(itemView);

    }



    @Override

    public void onBindViewHolder(final @NonNull MyHolder holder, final int position) {

        holder.setItemText(dataset.get(position));

}

main activity layout:

<FrameLayout

    xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    tools:context="MainActivity">

        <android.support.v7.widget.RecyclerView

            android:id="@+id/vRecyclerView"

            android:orientation="vertical"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"/>

</FrameLayout>

vertical item view layout:

<?xml version="1.0" encoding="utf-8"?>



<android.support.v7.widget.RecyclerView

    xmlns:android="http://schemas.android.com/apk/res/android"

    android:background="@color/colorAccent"

    android:id="@+id/hRecyclerView"

    android:focusableInTouchMode="true"

    android:focusable="true"

    android:orientation="horizontal"

    android:layout_width="wrap_content"

    android:layout_height="wrap_content"/>

horisontal item view layout:

<FrameLayout

    xmlns:android="http://schemas.android.com/apk/res/android"

    android:id="@+id/flContainer"

    android:layout_margin="5dp"

    android:focusable="true"

    android:layout_width="250dp"

    android:layout_height="150dp">



    <TextView

        android:id="@+id/tvItemText"

        android:textColor="@color/white"

        android:layout_gravity="center"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content" />

</FrameLayout>

I want stop this annoying auto scroll behavior.
Thanks.

please remove

android:focusableInTouchMode="true"

android:focusable="true"

and let me know the status.

You need to keep the state/position of each Horizontal RecyclerView's Adapter. When you are scrolling the vertical RecyclerView you are, obviously, recycling the views, therefor, if the horizontal adapter's state is not saved, when you scroll the vertical RecyclerView you will end up in some position for a scrolled Horizontal RecyclerView different than the one you were before the view was recycled.

Add this to your HAdapter class

private View.OnKeyListener mOnKeyListener = new View.OnKeyListener() {

    @Override

    public boolean onKey(View v, int keyCode, KeyEvent event) {

       RecyclerView rv = (RecyclerView) v.getParent();

       if (event.getAction() == KeyEvent.ACTION_DOWN && event.getKeyCode() == KeyEvent.KEYCODE_DPAD_UP) {

           rv.getLayoutManager().scrollToPosition(0);

       }          

       return false;

    }

};

and

itemView.setOnKeyListener(mOnKeyListener);

into the onCreateViewHolder method of your HAdapter class.

This one is only for the Arrow Up key, you can extend the if clause to include the Arrow Down key as well.

Edit:

Alternatively, you can put that into the if clause instead of scrollToPosition method call:

private View.OnKeyListener mOnKeyListener = new View.OnKeyListener() {

    @Override

    public boolean onKey(View v, int keyCode, KeyEvent event) {

        RecyclerView rv = (RecyclerView) v.getParent();

        if (event.getAction() == KeyEvent.ACTION_DOWN && event.getKeyCode() == KeyEvent.KEYCODE_DPAD_UP) {

           int pos = rv.getLayoutManager().getPosition(v);

           rv.scrollBy(-((int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, pos * width, mContext.getResources().getDisplayMetrics())), 0);

        }          

        return false;

    }

};

where width is the width of the RecyclerView item(s) in dp.

Suggestion:

I would move the setAdapter and setLayoutManager methods from the ViewHolder class into the HAdapter class body. (Do the same in the VAdapter class as well) They have nothing to do with the ViewHolder pattern. ViewHolder pattern is used to optimize performance by caching the views returned by findViewById()

Edit 2:

Add this class to your project:

https://raw.githubusercontent.com/wuakitv/leanback-v17/master/src/android/support/v17/leanback/widget/PersistentFocusWrapper.java

Then, modify your v_item_view.xml:

<?xml version="1.0" encoding="utf-8"?>



<lolkek.example.com.testrecycler.PersistentFocusWrapper

    xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="wrap_content"

    android:layout_height="wrap_content">



    <android.support.v7.widget.RecyclerView

        xmlns:android="http://schemas.android.com/apk/res/android"

        android:id="@+id/hRecyclerView"

        android:orientation="horizontal"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"/>



</lolkek.example.com.testrecycler.PersistentFocusWrapper>

I tested it, and it works.