question: public void addMapping ( String oldImg , int oldIndex , String newImg , int newIndex ) { newTilesets . add ( newImg ) ; HashMap < Integer , TileInfo > mapping = mappings . get ( oldImg ) ; if ( mapping == null ) { mapping = new HashMap < Integer , TileInfo > ( ) ; mappings . put ( oldImg , mapping ) ; } mapping . put ( oldIndex , new TileInfo ( newImg , newIndex ) ) ; }
target:  Add a new translation mapping.