Nested RecyclerView. How to prevent parent RecyclerView from getting scrolled while child RecyclerView is scrolling?

Question

I am trying to implement a horizontal recyclerview and each item of the recyclerview will be a vertical recyclerview with a grid layou

Answer 1

I fixed this issue in a similar project by taking the opposite approach to you (and everyone else here).

Rather than allow the child to tell the parent when to stop looking at events, I let the parent decide when to ignore (based on direction). This approach requires a custom view though which can be a little more work. Below is what I created which would be used as the Outer/Parent view.

public class DirectionalRecyclerView extends RecyclerView {

    private static float LOCK_DIRECTION_THRESHOLD; //The slop
    private float startX;
    private float startY;
    private LockDirection mLockDirection = null;

    public DirectionalRecyclerView(Context context) {
        super(context);
        findThreshold(context);
    }

    public DirectionalRecyclerView(Context context, AttributeSet attrs) {
        super(context, attrs);
        findThreshold(context)
    }

    public DirectionalRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        findThreshold(context);
    }

    private void findThreshold(Context context) {
        //last number is number of dp to move before deciding that's a direction not a tap, you might want to tweak it
        LOCK_DIRECTION_THRESHOLD = context.getResources().getDisplayMetrics().density * 12;
    }

    //events start at the top of the tree and then pass down to
    //each child view until they reach where they were initiated
    //unless the parent (this) method returns true for this visitor
    @Override
    public boolean onInterceptTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                startX = event.getX();
                startY = event.getY();
                break;
            case MotionEvent.ACTION_MOVE:
                if (mLockDirection == null) {
                    float currentX = event.getX();
                    float currentY = event.getY();
                    float diffX = Math.abs(currentX - startX);
                    float diffY = Math.abs(currentY - startY);
                    if (diffX > LOCK_DIRECTION_THRESHOLD) {
                        mLockDirection = LockDirection.HORIZONTAL;
                    } else if (diffY > LOCK_DIRECTION_THRESHOLD) {
                        mLockDirection = LockDirection.VERTICAL;
                    }
                } else {
                    //we have locked a direction, check whether we intercept
                    //the future touches in this event chain
                    //(returning true steals children's events, otherwise we'll
                    // just let the event trickle down to the child as usual)
                    return mLockDirection == LockDirection.HORIZONTAL;
                }
                break;
            case MotionEvent.ACTION_UP:
                mLockDirection = null;
                break;
        }
        //dispatch cancel, clicks etc. normally
        return super.onInterceptTouchEvent(event);
    }

    private enum LockDirection {
        HORIZONTAL,
        VERTICAL
    }

}

Answer 2

Use this code to turn off scroll on recyclerview:

recyclerView.setOnTouchListener(new View.OnTouchListener() {
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        return true;
    }
});

Answer 3

The problem exists in Android's implementation of the onInterceptTouchEvent() method for RecyclerView. This blog calls out the problem and fixes it as well - http://nerds.headout.com/fix-horizontal-scrolling-in-your-android-app/. The only difference is that there the parent scrolls vertically and child horizontally. But the solution takes care that it should work for your situation as well.

Answer 4

I used card view for cells and deactivated parent recycler view scrolling in child adapter with child cell itemView setOnClickListener.

holder.itemView.setOnTouchListener { view, _ ->
    view.parent.parent.requestDisallowInterceptTouchEvent(true)
    false
}

we are calling view.parent.parent because of the fact that itemView is a cell layout and it's parent is our child recyclerView and also, we need to reach child recyclerView's parent to prevent parent recyclerView scrolling.

Answer 5

You should do this way:

innerRecyclerView.addOnItemTouchListener(new RecyclerView.OnItemTouchListener() {

        @Override
        public void onTouchEvent(RecyclerView recycler, MotionEvent event) {
            // Handle on touch events here
            int action = event.getAction();
            switch (action) {
                case MotionEvent.ACTION_DOWN:

                    recycler.getParent().requestDisallowInterceptTouchEvent(true);

                    break;

                case MotionEvent.ACTION_UP:

                    recycler.getParent().requestDisallowInterceptTouchEvent(false);

                    break;

                case MotionEvent.ACTION_MOVE:

                    recycler.getParent().requestDisallowInterceptTouchEvent(true);

                    break;
            }


        }

        @Override
        public boolean onInterceptTouchEvent(RecyclerView recycler, MotionEvent event) {
            return false;
        }

    });

Hope this would help you.

Answer 6

Now you can try android:nestedScrollingEnabled because Google fixed a crash with usages of nestedScrollingEnabled (Issue 197932)