简易计算器

import java.awt.*;
import java.awt.event.*;

class Calculatorplus extends Frame
implements ActionListener
{
	TextField t1,t2,t3;	
	Button button1,button2,button3,button4;
	MenuBar menubar;
	Menu menu;
	MenuItem itemExit;
	Calculatorplus(String s)
	{
		super(s);
		setLayout(new FlowLayout());
		menubar=new MenuBar();
		menu =new Menu ("file");
		itemExit=new MenuItem("exit");
		itemExit.setShortcut(new MenuShortcut(KeyEvent.VK_E));
		menu.add(itemExit);
		menubar.add(menu);
		setMenuBar(menubar);
		itemExit.addActionListener(this);
		t1=new TextField(10);
		t2=new TextField(10);
		t3=new TextField(10);
		
		button1 =new  Button("+");
		button2 =new  Button("-");
		button3 =new  Button("*");
		button4 =new  Button("/");
		add(t1);
		add(t2);
		add(t3);
		t3.setEditable(false);
		add(button1);
		add(button2);
		add(button3);
		add(button4);
	    button1.addActionListener(this);
		button2.addActionListener(this);
		button3.addActionListener(this);
		button4.addActionListener(this);
		setBounds(500,100,150,150);
		setVisible(true);
		validate();
		
		addWindowListener(new WindowAdapter() {
			public void windowClosing(WindowEvent e){
				System.exit(0);
			}
		});
	}

	public void actionPerformed(ActionEvent e)
	{
		double  num1=0,num2=0,total;		
	

		try { 
				num1=Double.parseDouble(t1.getText());
				num2=Integer.parseInt(t2.getText());
				
				if(e.getSource()==button1)
				{
					total=num1+num2;
					t3.setText("和"+total);
				}
				else if(e.getSource()==button2)
				{
					total=num1-num2;
					t3.setText("差"+total);
				}
				else if(e.getSource()==button3)
				{
					total=num1*num2;
					t3.setText("积"+total);
				}
				else if(e.getSource()==button4)
				{
					total=num1/num2;
					t3.setText("除"+total);
				}
			
				
			} catch (Exception event) {
				// TODO: handle exception
				t3.setText("input correct number format");
			if (e.getSource()==itemExit) {System.exit(0);}
	}
}}


public class Calculator
{
	public static void main(String[] args) {
		new Calculatorplus("calculate");
		
	}
}