初学Java

package com.runoob.text;
//import java.io;
import java.awt.*;
import java.awt.event.*;
public class hello {
        public static void main(String []args) {
            ApplicationFrame AF= new ApplicationFrame();
        }
    }

class ApplicationFrame extends Frame implements ActionListener
{
    Label prompt;
    TextField text1,text2;
    Button btn;
    int a=0,b=0;
    ApplicationFrame()
    {
        super("计算器");
        prompt= new Label("请输入两个数：");
        text1= new TextField(4);
        text2= new TextField(4);
        btn =new Button("计算");
        setLayout(new FlowLayout());
        add(prompt);
        add(text1);
        add(text2);
        add(btn);
        btn.addActionListener(this);
        show();
    }
    public void actionPerformed(ActionEvent e)
    {
        a=Integer.parseInt(text1.getText());
        b=Integer.parseInt(text2.getText());
    }
    public void paint(Graphics g)
    {
        g.drawString("运算结果："+a+"*"+b+"="+a*b,20,80);
    }
}