udunits/src/main/java/ucar/units/StandardPrefixDB.java
public static synchronized StandardPrefixDB instance() throws PrefixDBException {
    if (instance == null) {
      try {
        instance = new StandardPrefixDB();
      } catch (final Exception e) {
        throw new PrefixDBException(
                "Couldn't create standard prefix-database", e);
      }
    }
    return instance;
  }
public static synchronized StandardPrefixDB instance() throws PrefixDBException {
    if (instance == null) {
      try {
        instance = new StandardPrefixDB();
      } catch (final Exception e) {
        throw new PrefixDBException(
                "Couldn't create standard prefix-database", e);
      }
    }
    return instance;
  }
Gets an instance of this database.

@return An instance of this database.
@throws PrefixDBException The instance couldn't be created.