Android RecyclerView Snap Adapter

SnapAdapter.java

// Horizontal snap adapter for recycler view, LinearSnapHelper is available from support lib 24.2.0
LinearSnapHelper snapHelper = new LinearSnapHelper() {
    @Override
    public int findTargetSnapPosition(RecyclerView.LayoutManager lm, int velocityX, int velocityY) {
        View centerView = findSnapView(lm);
        if (centerView == null)
            return RecyclerView.NO_POSITION;

        int position = lm.getPosition(centerView);
        int targetPosition = -1;
        if (lm.canScrollHorizontally()) {
            if (velocityX < 0) {
                targetPosition = position - 1;
            } else {
                targetPosition = position + 1;
            }
        }

        if (lm.canScrollVertically()) {
            if (velocityY < 0) {
                targetPosition = position - 1;
            } else {
                targetPosition = position + 1;
            }
        }

        final int firstItem = 0;
        final int lastItem = lm.getItemCount() - 1;
        targetPosition = Math.min(lastItem, Math.max(targetPosition, firstItem));
        return targetPosition;
    }
};
snapHelper.attachToRecyclerView(recyclerViewThumbnail);