question: private void filterOutInteriorOrExteriorZones ( final Set < StendhalRPZone > zonesInRegion , final Boolean exterior ) { final Set < StendhalRPZone > removals = new HashSet < StendhalRPZone > ( ) ; for ( StendhalRPZone zone : zonesInRegion ) { if ( exterior ) { if ( zone . isInterior ( ) ) { removals . add ( zone ) ; } } else { if ( ! zone . isInterior ( ) ) { removals . add ( zone ) ; } } } zonesInRegion . removeAll ( removals ) ; }
target:  Filter out exterior or interior zones from the given set