Why do we need addOnGlobalLayoutListener() on the third challange when

Android Programming (3rd Edition) 25. HTTP and Background Tasks
1

When i can just use the following code to adjust the width of the columns(240 is the default width of each column while on portrait mode):

`mPhotoRecyclerView.getViewTreeObserver().addOnPreDrawListener(
new ViewTreeObserver.OnPreDrawListener() {
        @Override
        public boolean onPreDraw() {
            int desiredColumnNumber = mPhotoRecyclerView.getMeasuredWidth() / 240;


            if ((mPhotoRecyclerView.getMeasuredWidth() % 240) > 0.5) {
                desiredColumnNumber ++;
            }

            gridLayoutManager.setSpanCount(desiredColumnNumber );
            return true;
        }
    });`