//即使返回成功消息后，我仍然會得到String return期望... //任何幫助將不勝感激public String addStudent(Student student) throws Exception {    try    {        Validator validate = new Validator();        validate.validate(student);        if((student.getMark1()<50 && student.getMark2()<50 && student.getMark3()<50) && student.getResult()=='P')            throw new Exception("Service.INVALID_RESULT_PASS");        if((student.getMark1()>=50 || student.getMark2()>=50 || student.getMark3()>=50) && student.getResult()=='F')            throw new Exception("Service.INVALID_RESULT_FAIL");        return "Success";    }    catch(Exception e)    {        System.out.println(e.getMessage());    }}