@Override public void addListener(DataSourceUpdatedInterface listener){
  if (!listenerList.contains(listener)) {
    listenerList.add(listener);
    if (getGeometryType() != GeometryTypeEnum.UNKNOWN) {
      notifyDataSourceLoaded();
    }
  }
}

@ Override public void addListener ( DataSourceUpdatedInterface listener ) { if ( ! listenerList . contains ( listener ) ) { listenerList . add ( listener ) ; if ( getGeometryType ( ) != GeometryTypeEnum . UNKNOWN ) { notifyDataSourceLoaded ( ) ; } } }
adds the data source updated listener .
