// packRecyclerView.getViewTreeObserver().addOnGlobalLayoutListener(); replace this line with the next one
packRecyclerView.getViewTreeObserver().addOnGlobalLayoutListener(onGlobalLayoutListener);

private ViewTreeObserver.OnGlobalLayoutListener onGlobalLayoutListener = new ViewTreeObserver
            .OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            // do something here
            //...
            // after that remove the listener
            globalLayout.getViewTreeObserver().removeOnGlobalLayoutListener(onGlobalLayoutListener);
        }
    };