question: private int estimateContentSize ( ) { int total = 0 ; int count = 0 ; for ( int i = mAdapter . getItemCount ( ) - 1 ; i >= 0 && count < mConfig . viewCountEstimateSize ; i -- ) { View view = mLayoutManager . findViewByPosition ( i + 1 ) ; if ( view != null ) { Rect rect = new Rect ( ) ; mLayoutManager . getDecoratedBoundsWithMargins ( view , rect ) ; int itemHeight = Math . abs ( directionVertical ( ) ? rect . height ( ) : rect . width ( ) ) ; count ++ ; total += itemHeight ; } } if ( count > 0 ) { double average = ( double ) total / count ; return ( int ) ( average * mAdapter . getItemCount ( ) ) ; } return 0 ; }
target:  Try to estimate the content size of the adapter inside the RecyclerView.