code: public static float requireFloatParameter (
          HttpServletRequest req, String name, String invalidDataMessage)
          throws DataValidationException
      {
          return parseFloatParameter(getParameter(req, name, false), invalidDataMessage);
      }
docs: Fetches the supplied parameter from the request and converts it to a float. If the parameter
  does not exist or is not a well-formed float, a data validation exception is thrown with the
  supplied message.