Question

我正在尝试在jsp中创建一个评分系统。如果属于特定类别，则必须检查总计，并给出等级和备注。这是我在Java类中编写的方法。

public void grade_adaptor(double sTotal,String Grade,String Remark){
 if(sTotal>=80){
            Grade="A";
            Remark="ADVANCE";
        }else if(sTotal>=75 && sTotal<=79.9){
            Grade="P";
            Remark="PROFICIENT";
        }else if(sTotal>=70 && sTotal<=74.9){
            Grade="AP";
            Remark="APPROACHING PROFICIENT";
        }else if(sTotal>=65 && sTotal<=69.9){
            Grade="D";
            Remark="DEVELOPING";
        }else if(sTotal>=0.0 && sTotal<=64.9){
            Grade="B";
            Remark="BEGINNING";
        }

 }

在我的jsp页面中，我有一个输入框，将输入该值，并且我想调用该方法以使其工作。这就是我所拥有的：

<%@page import="pack.Grading" %>
<!DOCTYPE html>
<head>
<link rel="stylesheet" href="st.css" type="text/csss"/>
</head>
<body>
<form action="update.jsp" method="post">
<input type="text" name="t_value" value="total_value"/>
<input type="submit" name="save" value="save"/>
</form>

//this is the code i wrote below
<% 
String value=request.getParameter("t_value");
if(value!=null){
//these are the variables i created for the method in the java class
double total=Double.valueOf(value);
String t_grade,t_remark;

/*this is the code i wrote to call the method into the page.
the class in which the method is created is called Grading
*/
Grading gr=new Grading();
gr.grade_adaptor(total,t_grade,t_remark);
//a dialog box to display the result
JOptionPane.showMessageDialog(null,"value: "+total+" grade: "+t_grade+" remark:"+t_remark);
}
%>

</form>
</body>
</html>

但是我在JOptionPane中得到的成绩和备注为空值。请我在做什么错。所有帮助将不胜感激。谢谢

Answer 1

核心OOP不匹配。方法定义有误（或未在目标中正确使用）：
public void grade_adaptor(double sTotal,String Grade,String Remark)
计算显示仅需要sTotal。

建议的更改：

class Result
{
    public String Grade;
    //or use getter
    String Remark;
    Result(String Grade,String Remark)
    {
        this.Grade = Grade;
        ...
    }
    ...
}

public Result grade_adaptor(double sTotal)
{
    if(sTotal>=80){
       return new Result("A","ADVANCE");
         ...  
}

Grading gr=new Grading();
Result r=gr.grade_adaptor(total);
//a dialog box to display the result
JOptionPane.showMessageDialog(null,"value: "+total+" grade: "+r.Grade+" remark:"+r.Remark);

如何在jsp页面中调用类中的方法

1 个答案: