question: public void moveChildView ( int fromGroupPosition , int fromChildPosition , int toGroupPosition , int toChildPosition ) { ArrayList < RoomSummary > fromList = mSummaryListByGroupPosition . get ( fromGroupPosition ) ; ArrayList < RoomSummary > toList = mSummaryListByGroupPosition . get ( toGroupPosition ) ; RoomSummary summary = fromList . get ( fromChildPosition ) ; fromList . remove ( fromChildPosition ) ; if ( toChildPosition >= toList . size ( ) ) { toList . add ( summary ) ; } else { toList . add ( toChildPosition , summary ) ; } }
target:  Move a childview in the roomSummary dir tree