java窗口加法器_java实现简单GUI加法器

用java编写一个简单的加法器，要求有GUI界面。

import java.awt.*;

import java.awt.event.ActionEvent;

import javax.swing.*;

import java.awt.event.ActionListener;

public class SUM extends JFrame {

public SUM(){

super("加法运算器");

setSize(370,150);

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

setVisible(true);

FlowLayout flo=new FlowLayout();

setLayout(flo);

final JTextField num1=new JTextField(4);

JButton addButton1=new JButton("+");

final JTextField num2=new JTextField(4);

JButton addButton2=new JButton("=");

final JTextField sum=new JTextField(8);

add(num1);

add(addButton1);

add(num2);

add(addButton2);

add(sum);

//加入监听器！！！- -关键是如何将String类型转换为Double类型

addButton2.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e){

JButton addButton2=(JButton)e.getSource();

double a1=Double.parseDouble(num1.getText());

double a2=Double.parseDouble(num2.getText());

sum.setText(String.valueOf(a2+a1));

//JTextField sum //怎么实现文本1和文本2相加并且在文本3输出？？？

}

}

);

}

public static void main(String[] args) {

// TODO code application logic here

SUM sal=new SUM();

}

}