public static synchronized StandardUnitDB instance() throws UnitDBException {
    if (instance == null) {
      try {
        instance = new StandardUnitDB();
      } catch (Exception e) {
        throw new UnitDBException("Couldn't create standard unit-database", e);
      }
    }
    return instance;
  }
public static synchronized StandardUnitDB instance() throws UnitDBException {
    if (instance == null) {
      try {
        instance = new StandardUnitDB();
      } catch (Exception e) {
        throw new UnitDBException("Couldn't create standard unit-database", e);
      }
    }
    return instance;
  }
public static synchronized StandardUnitDB instance ( ) throws UnitDBException { if ( instance == null ) { try { instance = new StandardUnitDB ( ) ; } catch ( Exception e ) { throw new UnitDBException ( "Couldn't create standard unit-database" , e ) ; } } return instance ; }
Gets an instance of this database.

@return An instance of this database.
@throws UnitDBException The instance couldn't be created.
Gets an instance of this database .