java计算器

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Calculator extends Frame implements ActionListener
...{
    static MenuBar mb = new MenuBar();//添加菜单
    static Menu menu = new Menu("Help");
    static MenuItem about = new MenuItem("About Calculator 1.0");
    static Calculator frame = new Calculator();
    static JPanel panel = new JPanel(new GridLayout(4, 4, 5, 5));
    static JPanel panel2 = new JPanel(new GridLayout(1, 2, 5, 5));
    static JButton[] button = new JButton[18]; 
    static JLabel label = new JLabel("0.", JLabel.RIGHT);
    StringBuffer buf = new StringBuffer();
    static String state = new String("Clean");//用来记录上一次的操作
    //static boolean pmmdState = false; //用来记录加减乘除过没有，默认没有
    static boolean pointState = false; //用来指示小数点状态,默认没按小数点
    static boolean zeroState = true; //用来指示0在首位的状态,true表示在首位
    static boolean zeroState2 = false; //用来记录按了一次0键没有，默认没按
    static boolean numState = false; //指示在小数点之前按了数字键没有,默认没按
    static boolean signState = true; //指示正负号, true为正, false为负.
    static boolean likeEqual = false; //指示按加减乘除时该不该计算出结果.默认不该
    static boolean keyLock = false; //按键锁，当发生除0异常时，锁住除Clean键以外的所有键,默认没锁
    String str = new String();
    double num1 = 0, num2 = 0;
    public static void main(String[] args)
    ...{
        int i;
        menu.add(about);//菜单
        mb.add(menu);
        about.addActionListener(frame);
        frame.setMenuBar(mb);
        frame.setTitle("Calculator");
        frame.setLayout(null);
        frame.setSize(290, 320);
        frame.setVisible(true);
        frame.setResizable(false); //若程序无法显示完整的图形界面，可将它设为true
        frame.addWindowListener(new WindowAdapter()
        ...{
                public void windowClosing(WindowEvent e)
                ...{
                    System.exit(0);
                }
        });
        panel.setBounds(20, 130, 250, 165);
        panel2.setBounds(20, 90, 250, 33);
        label.setBounds(20, 50, 250, 35);
        label.setFont(new Font("result", Font.PLAIN, 18));
        label.setOpaque(true);
        label.setBackground(new Color(125, 125, 180));
        Font font = new Font("Times New Roman", Font.PLAIN, 16);
        for(i = 0; i < 18; i++)
        ...{
            button[i] = new JButton();
            button[i].setFont(font);
        }
        for(i = 1; i < 10; i++)
        ...{
            button[i].setText(Integer.toString(i));
            panel.add(button[i]);
        }
        button[0].setText("0");
        button[10].setText("+/-");
        button[11].setText(".");
        panel.add(button[0]);
        panel.add(button[10]);
        panel.add(button[11]);
        button[12].setText("+");
        button[13].setText("-");
        button[14].setText("*");
        button[15].setText("/");
        panel.add(button[12], 3);
        panel.add(button[13], 7);
        panel.add(button[14], 11);
        panel.add(button[15], 15);
        button[16].setText("Clean");
        button[17].setText("=");
        panel2.add(button[16], 0);
        panel2.add(button[17], 1);
        frame.add(label);
        frame.add(panel);
        frame.add(panel2);
        for(i = 0; i < 18; i++)
        ...{
            button[i].addActionListener(frame);
            button[i].setActionCommand(button[i].getText());
        }
    }
    public void actionPerformed(ActionEvent e)
    ...{
        int i;
        String[] estate = ...{"+", "-", "*", "/", "="};
        for(i = 1; i < 10; i++)//1-9数字键
        ...{
            if(e.getActionCommand().equals(Integer.toString(i)) && keyLock == false)
            ...{
                if(pointState == false)
                ...{
                    str = new String(buf.append(i) + ".");
                    label.setText(str);
                    numState = true;
                    break;
                }
                else
                ...{
                    str = new String(buf.append(i));
                    label.setText(str);
                    numState = true;
                    break;
                }
            }
        }
        if(e.getActionCommand().equals("0") && keyLock == false)//0键
        ...{
            zeroState2 = true;
            if(zeroState == true && numState == false && pointState == false)//这句也很关键
            ...{
                label.setText("0.");
                buf = new StringBuffer("0");//这条语句关系到后面的异常处理
            }
            else
            ...{
                zeroState = false;
                if(pointState == false)
                ...{
                    str = new String(buf.append(0) + ".");
                    label.setText(str);
                    numState = true;
                }
                else
                ...{
                    str = new String(buf.append(0));
                    label.setText(str);
                }
            }
        }
        if(e.getActionCommand().equals(".") && keyLock == false)//小数点键
            if(pointState == false)
            ...{
                if(numState == false)
                ...{
                    if(zeroState2 == true)//判断按了0键没有
                        buf.append(".");
                    else
                        buf.append("0.");
                    label.setText(new String(buf));//这句必须要有
                    pointState = true;
                }
                else
                ...{
                    buf.append(".");
                    label.setText(new String(buf));
                    pointState = true;
                }
            }
        if(e.getActionCommand().equals("Clean"))//Clean键
        ...{
            buf = new StringBuffer();
            label.setText("0.");
            state = new String("Clean"); //记录上次操作
            pointState = false;
            zeroState = true;
            zeroState2 = false;
            numState = false;
            signState = true;
            likeEqual = false;
            keyLock = false; //撤消按键锁
        }
        for(i = 0; i < 4; i++)//+-*/运算
        ...{
            activeLikeEqual();
            if(e.getActionCommand().equals(estate[i]) && keyLock == false)
            ...{
                if(likeEqual == false)
                ...{
                    num1 = num2 = Double.parseDouble(label.getText());
                    buf = new StringBuffer();
                    state = new String(estate[i]);
                    pointState = false;//将小数点再次设置为未使用
                    zeroState = true;
                    zeroState2 = false; 
                    numState = false;
                    signState = true;
                    break;
                }
                else
                ...{
                    resultOperate();
                    renewState();
                    state = new String(estate[i]);
                    num2 = num1; //1+2+=之类的操作
                }
            }
        }
        
        if(e.getActionCommand().equals("=") && keyLock == false)//=运算
        ...{
            if(state.equals("Clean"))
            ...{
                    label.setText(label.getText());//又解决一个bug -> 按3=显示0.
                    buf = new StringBuffer();
                    state = new String("Clean"); //记录上次操作
                    pointState = false;
                    zeroState = true;
                    zeroState2 = false;
                    numState = false;
                    signState = true;
            }
            else
            ...{
                resultOperate();
                renewState();
            }
        }
        
        if(e.getSource() == about)
        ...{
            JOptionPane.showMessageDialog(frame, "Version: Calculator 1.0  Author: Mr. tan  All Rights Reserved",
            "About Calculator 1.0", JOptionPane.INFORMATION_MESSAGE);
        }
        if(e.getActionCommand().equals("+/-") && keyLock == false)
        ...{
            if(zeroState == true && numState == false && pointState == false)
            ...{
            }
            else
            ...{
                if(signState == true)
                ...{
                    buf.insert(0, '-');
                    if(pointState == false)
                        label.setText(new String(buf) + ".");
                    else
                        label.setText(new String(buf));
                    signState = false;
                }
                else
                ...{
                    buf.deleteCharAt(0);
                    if(pointState == false)
                        label.setText(new String(buf) + ".");
                    else
                        label.setText(new String(buf));
                    signState = true;
                }
            }
        }
    }
    
    //计算结果的方法，因为有时候按+-*/号时也需要计算出结果，所以把它写在一起节省代码。
    public void resultOperate()
    ...{
        if(buf.length() > 0)
        ...{
            str = new String(buf); //考虑这用buf还是label.getText()
            num2 = Double.parseDouble(str);
        }
        //else num2 = num1; //1+2+=之类的操作
        if(state.equals("+"))
            num1 += num2;
        else if(state.equals("-"))
            num1 -= num2;
        else if(state.equals("*"))
            num1 *= num2;
        if(state.equals("/")) //对/要进行异常处理
        ...{
            try
            ...{
                if(num2 != 0)
                ...{
                    num1 /= num2;
                }
                else
                    throw new ArithmeticException();
            }
            catch(ArithmeticException ZeroException)
            ...{
                label.setText("I think your IQ is only 80!!");
                keyLock = true;//启动按键锁
                return;//防止出现9/0=9这样的bug
            }
        }
        StringBuffer calculateResult = new StringBuffer(Double.toString(num1));
        if(calculateResult.charAt(calculateResult.length() - 2) == '.' && 
            calculateResult.charAt(calculateResult.length() - 1) == '0')
            calculateResult.deleteCharAt(calculateResult.length() - 1);
        label.setText(new String(calculateResult));    
    }
    public void activeLikeEqual()//激活+-*/的计算功能
    ...{
        if((state.equals("+") || state.equals("-") ||
        state.equals("*") || state.equals("/")) && 
        buf.length() > 0)
            likeEqual = true;
    }
    public void renewState()
    ...{
        buf = new StringBuffer();
        pointState = false;
        zeroState = true;
        zeroState2 = false;
        numState = false;
        signState = true;
        likeEqual = false;
    }
}