java编程实现极简的计算器

JAVA实现一个极简的计算器，只实现了   +   -    ×   ÷  功能！

亲测可用！

import java.awt.*;
import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;	

public class calculator extends JFrame implements ActionListener
{
	JFrame frame;
	JButton button1,button2,button3,button4;
	JTextField JTextField1,JTextField2,JTextField3;
	JLabel JL1,JL2,JL3;
	public static void main(String args[])
	{	calculator a = new calculator ();
		a.go();
	}

	public void go()
	{	
		this.setTitle("Calculator");        //窗口设置
		this.setSize(200,300);
		this.setLayout(new FlowLayout());	//为内容窗格设置FlowLayout布局管理
		Container contentPane = this.getContentPane();
		
		JTextField1 = new JTextField(15);
		JTextField2 = new JTextField(15);
		JTextField3 = new JTextField(15);
		
		JL1 = new JLabel("数字1");
		JL2 = new JLabel("数字2");
		JL3 = new JLabel("结果");

		button1 = new JButton("+");		//添加按钮
		button1.addActionListener(this);		//事件监听
		button2 = new JButton("-");
		button2.addActionListener(this);
		button3 = new JButton("*");
		button3.addActionListener(this);
		button4 = new JButton("/");
		button4.addActionListener(this);
		
		contentPane.add(JL1);               //布局顺序
		contentPane.add(JTextField1);
		contentPane.add(JL2);
		contentPane.add(JTextField2);
		contentPane.add(JL3);
		contentPane.add(JTextField3);
		contentPane.add(button1);
		contentPane.add(button2);
		contentPane.add(button3);
		contentPane.add(button4);

		
		this.setVisible(true);
	}
	public void actionPerformed(ActionEvent e) 
	{    
		if(e.getSource()==button1)
		{
		JTextField3.setText(String.valueOf(Double.parseDouble(JTextField1.getText())+Double.parseDouble(JTextField2.getText())));
		}
		else if(e.getSource()==button2)
		{
		JTextField3.setText(String.valueOf(Double.parseDouble(JTextField1.getText())-Double.parseDouble(JTextField2.getText())));
		}
		else if(e.getSource()==button3) 
		{
		JTextField3.setText(String.valueOf(Double.parseDouble(JTextField1.getText())*Double.parseDouble(JTextField2.getText())));
		}
		else 
		{
		if(Double.parseDouble(JTextField2.getText())==0.0) 
		{
		JTextField3.setText("除数不能为零");
		}
		else
		JTextField3.setText(String.valueOf(Double.parseDouble(JTextField1.getText())/Double.parseDouble(JTextField2.getText())));
		}
	 
	}
}