package myPacket;

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

public class Calculator
{
    private Frame f = new Frame("计算器");		// 主窗口 显示计算器主界面
    private Frame info = new Frame("关于");	// 介绍窗口

    private Button[] b = new Button[10];	// 声明数字按钮
    private Button[] cal = new Button[8];	// 声明功能按钮

    private MenuBar mb = new MenuBar();		// 菜单工具栏
    private Menu option = new Menu("操作");	// 操作菜单按钮
    private Menu other = new Menu("Other");			// 其他菜单按钮
    private MenuItem about = new MenuItem("about");
    private MenuItem reset = new MenuItem("reset");
    private MenuItem exit = new MenuItem("Exit");
    private Label information = new Label();

    private TextField text = new TextField(30);		// 输入文本框
    private int flag = 0;		//	重置标记	
    private int flag2 = -1;		//	对文本框中是否有内容进行标记 有则设置为 -1	数字键标记
    private int Key = -1;		//	 + - * / 运算标记

    String load1 = new String();
    String load2 = new String();

    public void init()	// 初始化
    {
        Panel p = new Panel();
        NumListener numListen = new NumListener();	// 数字键
        CalListener calListen = new CalListener();	// 功能键

        load1 = load2 = null;

        for(int i = 0; i <= 9; i++)
            b[i] = new Button(""+i);	// 初始化数字键按钮

        info.setSize(200,400);		// 初始化信息窗口大小
        information.setText("Java Calculator");		// 设置信息内容

        for(int i = 0; i <= 9; i++)
            b[i].addActionListener(numListen);	// 给按钮添加数字键的事件监听器

        cal[0] = new Button("+");
        cal[1] = new Button("-");
        cal[2] = new Button("*");
        cal[3] = new Button("/");
        cal[4] = new Button("=");
        cal[5] = new Button("退格");	// 退格键
        cal[6] = new Button(".");
        cal[7] = new Button("AC");
        cal[0].addActionListener(calListen);
        cal[1].addActionListener(calListen);
        cal[2].addActionListener(calListen);
        cal[3].addActionListener(calListen);
        cal[4].addActionListener(calListen);
        cal[5].addActionListener(e->
        {
        	if (text.getText().length() == 0) {
        		System.out.println("无字符");
        	}else {
                text.setText(text.getText().substring(0,text.getText().length()-1));        		
        	}
        });
        cal[6].addActionListener(e->
        {
            text.setText(text.getText()+".");	//	添加小数点
        });
        //	在面板上依次添加数据按钮和功能按钮
        p.add(b[1]);p.add(b[2]);p.add(b[3]);p.add(cal[0]);
        p.add(b[4]);p.add(b[5]);p.add(b[6]);p.add(cal[1]);
        p.add(b[7]);p.add(b[8]);p.add(b[9]);p.add(cal[2]);
        p.add(cal[5]);p.add(b[0]);p.add(cal[6]);p.add(cal[3]);
        p.add(cal[7]);p.add(cal[4]);

        text.setEditable(false);	// 禁止对文本框进行编辑
        exit.addActionListener(e->System.exit(0));		// 给菜单按钮添加事件监听 退出
        reset.addActionListener(e->
        {
            load1 = load2 = null;
            Key = -1;
            flag2 = -1;
            flag = 0;
            text.setText("");	//	重置时清空输入窗格
        });
        cal[7].addActionListener(e->	//	AC 键的功能为重置
        {
            load1 = load2 = null;
            Key = -1;
            flag2 = -1;
            flag = 0;
            text.setText("");	
        });
        about.addActionListener(e->
        {
            info.setVisible(true);		// 弹出信息窗格
        });

        option.add(reset);
        option.add(exit);
        other.add(about);
        mb.add(option);
        mb.add(other);		
        f.setMenuBar(mb);	//	设置工具条


        f.add(text,BorderLayout.NORTH);		//	设置文本框的布局
        p.setLayout(new GridLayout(5,4,4,4));	//	设置布局 5 行 4 列 ；水平 4 个 垂直 4 个

        info.add(information);
        info.addWindowListener(new WindowListener());	//	设置对窗口事件的监听器
        f.addWindowListener(new WindowListener());
        f.add(p);	//	将面板添加到窗口
        f.setSize(640,480);		// 设置计算器窗口大小
        f.setVisible(true);
    }
    //	窗口事件监听器
    class WindowListener extends WindowAdapter
    {
        public void windowClosing(WindowEvent e)	// 对关闭窗口事件进行响应
        {
            if(e.getSource() == f)
                System.exit(0);
            else if(e.getSource() == info)
                info.setVisible(false);
        }
    }
    // 数字键的事件监听器
    class NumListener implements ActionListener		
    {
        public void actionPerformed(ActionEvent e) 
        {
            if(e.getSource() == b[0])
            {
                if(flag2 == -1)		//	文本框中已有内容时
                    text.setText(text.getText()+"0");
                else
                {
                    text.setText("0");	// 数字 0
                    flag2 = -1;
                }
            }
            else if(e.getSource() == b[1])
            {
                if(flag2 == -1)
                    text.setText(text.getText()+"1");
                else
                {
                    text.setText("1");	// 数字 1
                    flag2 = -1;
                }
            }
            else if(e.getSource() == b[2])
            {
                if(flag2 == -1)
                    text.setText(text.getText()+"2");
                else
                {
                    text.setText("2");	// 数字 2
                    flag2 = -1;
                }
            }
            else if(e.getSource() == b[3])
            {
                if(flag2 == -1)
                    text.setText(text.getText()+"3");
                else
                {
                    text.setText("3");	// 数字 3	
                    flag2 = -1;
                }
            }
            else if(e.getSource() == b[4])
            {
                if(flag2 == -1)
                    text.setText(text.getText()+"4");
                else
                {
                    text.setText("4");	// 数字 4
                    flag2 = -1;
                }
            }
            else if(e.getSource() == b[5])
            {
                if(flag2 == -1)
                    text.setText(text.getText()+"5");
                else
                {
                    text.setText("5");	// 数字 5
                    flag2 = -1;
                }
            }
            else if(e.getSource() == b[6])
            {
                if(flag2 == -1)
                    text.setText(text.getText()+"6");
                else
                {
                    text.setText("6");	// 数字 6
                    flag2 = -1;
                }
            }
            else if(e.getSource() == b[7])
            {
                if(flag2 == -1)
                    text.setText(text.getText()+"7");
                else
                {
                    text.setText("7");	// 数字 7
                    flag2 = -1;
                }
            }
            else if(e.getSource() == b[8])
            {
                if(flag2 == -1)
                    text.setText(text.getText()+"8");
                else
                {
                    text.setText("8");	// 数字 8
                    flag2 = -1;
                }
            }
            else if(e.getSource() == b[9])
            {
                if(flag2 == -1)
                    text.setText(text.getText()+"9");
                else
                {
                    text.setText("9");	// 数字 9
                    flag2 = -1;
                }
            }
        }       
    }

    class CalListener implements ActionListener		//	功能按键的事件监听
    {
        public void actionPerformed(ActionEvent e) 
        {
            if(e.getSource() == cal[0])		// + 按钮
            {
                if(flag == 0)
                {
                    load1 = text.getText();
                    flag = 1;
                    flag2 = Key = 0;
                }
                else if(flag == 1)
                {
                    load2 = text.getText();
                    text.setText(String.valueOf(Double.parseDouble(load1) + Double.parseDouble(load2)));
                    load1 = text.getText();
                    load2 = null;
                    //flag = 0;
                }
            }
            else if(e.getSource() == cal[1])	//	- 按钮
            {
                if(flag == 0)
                {
                    load1 = text.getText();
                    flag = 1;
                    flag2 = Key = 1;
                }
                else if(flag == 1)
                {
                    load2 = text.getText();
                    text.setText(String.valueOf(Double.parseDouble(load1) - Double.parseDouble(load2)));
                    load1 = text.getText();
                    load2 = null;
                    //flag = 0;
                }
            }
            else if(e.getSource() == cal[2])	// * 按钮
            {
                if(flag == 0)
                {
                    load1 = text.getText();
                    flag = 1;
                    flag2 = Key = 2;
                }
                else if(flag == 1)
                {
                    load2 = text.getText();
                    text.setText(String.valueOf(Double.parseDouble(load1) * Double.parseDouble(load2)));
                    load1 = text.getText();
                    load2 = null;
                    //flag = 0;
                }
            }
            else if(e.getSource() == cal[3])	//	除法 按钮
            {
                if(flag == 0)
                {
                    load1 = text.getText();
                    flag = 1;
                    flag2 = Key = 3;
                }
                else if(flag == 1)
                {
                    load2 = text.getText();
                    text.setText(String.valueOf(Double.parseDouble(load1) / Double.parseDouble(load2)));
                    load1 = text.getText();
                    load2 = null;
                    //flag = 0;
                }
            }
            else if(e.getSource() == cal[4])	//	= 按钮
            {
                if(load1 != null && load2 == null)
                {
                    load2 = text.getText();
                    if(Key == 0)
                        text.setText(String.valueOf(Double.parseDouble(load1) + Double.parseDouble(load2)));
                    else if(Key == 1)
                        text.setText(String.valueOf(Double.parseDouble(load1) - Double.parseDouble(load2)));
                    else if(Key == 2)
                        text.setText(String.valueOf(Double.parseDouble(load1) * Double.parseDouble(load2)));
                    else if(Key == 3)
                        text.setText(String.valueOf(Double.parseDouble(load1) / Double.parseDouble(load2)));
                    Key = -1;
                    flag = 0;
                    flag2 = -1;
                    load1 = text.getText();
                    load2 = null;
                }
            }
        }
    }

    public static void main(String[] args)
    {        		
        new Calculator().init();
    }
}