code: @Override
    protected Double handleRow(ResultSet rs) throws SQLException {
      if (this.columnName == null) {
        return rs.getDouble(this.columnIndex);
      }
      return rs.getDouble(this.columnName);
    }
docs: Returns one <code>ResultSet</code> column value as <code>Object</code>.
  
  @param rs <code>ResultSet</code> to process.
  @return <code>Object</code>, never <code>null</code>.
  @throws SQLException if a database access error occurs
  @throws ClassCastException if the class datatype does not match the column type
  @see org.apache.commons.dbutils.handlers.AbstractListHandler#handle(ResultSet)