@Override
  public Method getEvalMethod(List<TypeInfo> argClasses) throws UDFArgumentException {
    return MethodUtils.getMethodInternal(udfClass, "evaluate", false,
        argClasses);
  }
Gets the evaluate method for the UDF given the parameter types.

@param argClasses
         The list of the argument types that need to matched with the
         evaluate function signature.
udf/src/java/org/apache/hadoop/hive/ql/exec/DefaultUDFMethodResolver.java