Question

下面是我的代码，我将重点介绍错误是什么，我完全不知道如何解决这个错误...

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.awt.event.ActionListener.*;
import java.awt.event.TextListener.*;
public abstract class GradeAverage extends Applet
implements ActionListener, TextListener{
Button Ok=new Button("Ok");
Button Cancel=new Button("cancel");
TextField Math=new TextField("Math Grade",2);
TextField Science=new TextField("Scien Grade",2);
TextField SocialStudies=new TextField("Social Studies Grade",2);
TextField English=new TextField("English Grade",2);
TextField Elective=new TextField("Elective Grade",2);
TextField Elective2=new TextField("2nd Elective Grade",2);
TextArea message=new TextArea();
public void init(){
GridBagLayout gbl=new GridBagLayout();
setLayout(gbl);
GridBagConstraints c=new GridBagConstraints();
c.anchor=GridBagConstraints.WEST;
c.weightx=2.0;
c.weighty=2.0;
c.fill=GridBagConstraints.HORIZONTAL;
c.insets=new Insets(10,10,10,10);
gbl.setConstraints(Math,c); add(Math);
c.fill=GridBagConstraints.NONE;
gbl.setConstraints(Science,c); add(Science);
c.fill=GridBagConstraints.HORIZONTAL;
gbl.setConstraints(SocialStudies,c); add(SocialStudies);
c.gridy=1;
gbl.setConstraints(English,c); add(English);
c.gridy=2;
gbl.setConstraints(Elective,c); add(Elective);
c.fill=GridBagConstraints.NONE;
gbl.setConstraints(Elective2,c); add(Elective2);
c.gridy=3;
c.anchor=GridBagConstraints.CENTER;
gbl.setConstraints(Ok,c); add(Ok);
gbl.setConstraints(Cancel,c); add(Cancel);
c.gridy=4;
c.gridwidth=3;
c.fill=GridBagConstraints.BOTH;
gbl.setConstraints(message,c); add(message);
Math.addTextListener(this);
Science.addTextListener(this);
SocialStudies.addTextListener(this);
English.addTextListener(this);
Elective.addTextListener(this);
Elective2.addTextListener(this);
Ok.addActionListener(this);
Cancel.addActionListener(this);
}
public void actionPerformed(ActionEvent event){
Object Source=event.getSource();
if(Source==Ok){
Math.getText();
Science.getText();
SocialStudies.getText();
English.getText();
Elective.getText();
Elective2.getText();
do{ 
**message=(Math+Science+SocialStudies+English+Elective+Elective2)/6;**
system.println("Your grade average is"+message);
}while (message<0);
if(Source==Cancel){
system.ext(0);
}
}}}

抛出错误的代码标有** 给出的错误是：二元运算符'+'

的坏操作数类型

请帮忙！

由于

Answer 1

您不能将TextFields添加到一起，Java不支持重载。要获得该值，您必须先在getText()上调用TextField，然后将其传递给Double.parseDouble，将其转换为Java可以添加的数字。

你应该有这样的东西：

double gpa = (Double.parseDouble(Math.getText()) +
              ...
              Double.parseDouble(Elective2.getText())
             ) / 6;

如果任何NumberFormatException包含无法转换为数字的文字，则需要抓取TextField。

然后，您需要将GPA转换为TextArea您调用message的文本。

message.setText(String.valueOf(gpa));

Answer 2

看起来您正在尝试将字符串变量添加到一起 - 尝试首先将它们转换为整数值。

之类的东西

 message=(Integer.parseInt(Math)+Integer.parseInt(Science)+Integer.parseInt(English)...

以下是此主题的另一个主题的链接：How to convert a String to an int in Java?

希望这能帮到你！

如何从文本字段添加输入

2 个答案: