求助：计算器的源代码

[wxh512]

我想用swing做一个和windows自带的计算器一样功能的计算器：
想了好久不会做：

[swinging]

建议，接着想。
^_^

[gbl777]

这个也太easy了吧!
这个可是入门级的,有点编程基础的人都会呀!

[ssht968]

好。

[yangFrame]

不过不太完善

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

public class Calculator {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
CalculatorFrame frame=new CalculatorFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.show();
}
}

class CalculatorFrame extends JFrame{
public CalculatorFrame(){
setTitle("Calculator");
setSize(WIDTH,HEIGHT);

Container contentPane=getContentPane();
CalculatorPanel panel=new CalculatorPanel();
contentPane.add(panel);
}
public static final int WIDTH=200;
public static final int HEIGHT=200;
}

class CalculatorPanel extends JPanel
{
public CalculatorPanel()
{
setLayout(new BorderLayout());

result=0;
lastCommand="=";
start=true;

display=new JTextField("0");
display.setEditable(false);
add(display,BorderLayout.NORTH);

ActionListener insert=new InsertAction();
ActionListener command=new CommandAction();

panel=new JPanel();
panel.setLayout(new GridLayout(4,4));

addButton("7",insert);
addButton("8",insert);
addButton("9",insert);
addButton("/",command);

addButton("4",insert);
addButton("5",insert);
addButton("6",insert);
addButton("*",command);

addButton("1",insert);
addButton("2",insert);
addButton("3",insert);
addButton("-",command);

addButton("0",insert);
addButton(".",insert);
addButton("=",command);
addButton("+",command);

add(panel,BorderLayout.CENTER);
}

private void addButton(String label,ActionListener listener)
{
JButton button=new JButton(label);
button.addActionListener(listener);
panel.add(button);
}

private class InsertAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
String input=event.getActionCommand();
if(start)
{
display.setText("");
start=false;
}
display.setText(display.getText()+input);
}
}

private class CommandAction implements ActionListener
{
public void actionPerformed(ActionEvent evt)
{
String command=evt.getActionCommand();
if(start)
{
if(command.equals("="))
{
display.setText(command);
start=false;
}
else
lastCommand=command;
}
else
{
calculate(Double.parseDouble(display.getText()));
lastCommand=command;
start=true;
}
}
}

public void calculate(double x)
{
if(lastCommand.equals("+")) result+=x;
else if(lastCommand.equals("-")) result-=x;
else if(lastCommand.equals("*")) result*=x;
else if(lastCommand.equals("/")) result/=x;
else if(lastCommand.equals("=")) result=x;
display.setText(""+result);
}

private JTextField display;
private JPanel panel;
private double result;
private String lastCommand;
private boolean start;
}

[wxh512]

怎么加入菜单

[yangFrame]

JMenuBar menuBar=newJMenuBar();
frame.setJMnuBar(menuBar);