import java.awt.*;
import java.lang.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.*;
import java.text.DecimalFormat;
public class Calculator
    implements ActionListener { //導入動作監聽接口
  //設計面板中的單位
  JFrame frame;
  JTextField textAnswer;
  JPanel panel, panel1, panel2, panel3;
  JMenuBar mainMenu;
  JTextField textMemory;
  JLabel labelMemSpace; //labelMemSpace單純做擺設，控制面板的形狀
  JButton buttonBk, buttonCe, buttonC;
  JButton button[];
  JButton buttonMC, buttonMR, buttonMS, buttonMAdd;
  JButton buttonDot, buttonAddAndSub, buttonAdd, buttonSub, buttonMul,
      buttonDiv, buttonMod;
  JButton buttonSqrt, buttonDao, buttonEqual;
  JMenu editMenu, viewMenu, helpMenu;
  JMenuItem copyItem, pasteItem, tItem, sItem, numberGroup, topHelp, aboutCal;
  DecimalFormat df; //設置數據輸出精度
  boolean clickable; //控制當前能否按鍵
  double memoryd; //使用內存中存儲的數字
  int memoryi;
  double vard, answerd; //用來保存double型數據的中間值(vard)和最后結果(answerd)
  short key = -1, prekey = -1; //key用來保存當前進行何種運算,prekey用來保存前次進行何種運算
  String copy; //做復制用
  JTextArea help; //幫助
  JScrollPane scrollHelp;
  //構造函數
  public Calculator() {
    clickable = true;
    answerd = 0;
    frame = new JFrame("計算器");
    df = new DecimalFormat("0.##############"); //設置數據輸出精度(對于double型值)
    textAnswer = new JTextField(15);
    textAnswer.setText("");
    textAnswer.setEditable(false);
    textAnswer.setBackground(new Color(255, 255, 255));
    panel = new JPanel();
    frame.getContentPane().add(panel);
    panel1 = new JPanel();
    panel2 = new JPanel();
    panel.setLayout(new BorderLayout());
    //設計整個面板
    mainMenu = new JMenuBar();
    editMenu = new JMenu("編輯(E)");
    viewMenu = new JMenu("查看(V)");
    helpMenu = new JMenu("幫助(H)");
    copyItem = new JMenuItem("   復制(C) Ctrl+C");
    copyItem.addActionListener(this);
    pasteItem = new JMenuItem("   粘貼(V) Ctrl+V");
    pasteItem.addActionListener(this);
    editMenu.add(copyItem);
    editMenu.add(pasteItem);
    tItem = new JMenuItem("●標準型(T)");
    tItem.addActionListener(this);
    sItem = new JMenuItem("   科學型(S)");
    sItem.addActionListener(this);
    numberGroup = new JMenuItem("   數字分組(I)");
    numberGroup.addActionListener(this);
    viewMenu.add(tItem);
    viewMenu.add(sItem);
    viewMenu.add(numberGroup);
    topHelp = new JMenuItem("   幫助主題(H)");
    topHelp.addActionListener(this);
    help = new JTextArea(5, 20);
    scrollHelp = new JScrollPane(help);
    help.setEditable(false);
    help.append("執行簡單計算\n");
    help.append("1.  鍵入計算的第一個數字。\n");
    help.append("2.  單擊“+”執行加、“-”執行減、“*”執行乘或“/”執行除。\n");
    help.append("3.  鍵入計算的下一個數字。\n");
    help.append("4.  輸入所有剩余的運算符和數字。\n");
    help.append("5.  單擊“=”。\n");
    aboutCal = new JMenuItem("   關于計算器(A)");
    aboutCal.addActionListener(this);
    helpMenu.add(topHelp);
    helpMenu.add(aboutCal);
    mainMenu.add(editMenu);
    mainMenu.add(viewMenu);
    mainMenu.add(helpMenu);
    panel.add(mainMenu, BorderLayout.NORTH);
    panel.add(textAnswer, BorderLayout.CENTER);
    panel.add(panel1, BorderLayout.SOUTH);
    panel1.setLayout(new BorderLayout());
    textMemory = new JTextField(3);
    textMemory.setEditable(false);
    textMemory.setBackground(new Color(217, 217, 217));
    labelMemSpace = new JLabel("                   ");
    buttonBk = new JButton("Backspace");
    buttonBk.setForeground(new Color(255, 0, 0));
    buttonCe = new JButton("CE");
    buttonCe.setForeground(new Color(255, 0, 0));
    buttonC = new JButton("C");
    buttonC.setForeground(new Color(255, 0, 0));
    buttonBk.addActionListener(this);
    buttonCe.addActionListener(this);
    buttonC.addActionListener(this);
    panel1.add(panel2, BorderLayout.NORTH);
    panel2.setLayout(new FlowLayout(FlowLayout.RIGHT));
    panel2.add(textMemory);
    panel2.add(labelMemSpace);
    panel2.add(buttonBk);
    panel2.add(buttonCe);
    panel2.add(buttonC);
    panel3 = new JPanel();
    panel1.add(panel3, BorderLayout.CENTER);
    button = new JButton[10];
    for (int i = 0; i < button.length; i++) {
      button[i] = new JButton(Integer.toString(i));
      button[i].setForeground(new Color(0, 0, 255));
    }
    buttonMC = new JButton("MC");
    buttonMC.setForeground(new Color(255, 0, 0));
    buttonMR = new JButton("MR");
    buttonMR.setForeground(new Color(255, 0, 0));
    buttonMS = new JButton("MS");
    buttonMS.setForeground(new Color(255, 0, 0));
    buttonMAdd = new JButton("M+");
    buttonMAdd.setForeground(new Color(255, 0, 0));
    buttonDot = new JButton(".");
    buttonDot.setForeground(new Color(0, 0, 255));
    buttonAddAndSub = new JButton("+/-");
    buttonAddAndSub.setForeground(new Color(0, 0, 255));
    buttonAdd = new JButton("+");
    buttonAdd.setForeground(new Color(255, 0, 0));
    buttonSub = new JButton("-");
    buttonSub.setForeground(new Color(255, 0, 0));
    buttonMul = new JButton("*");
    buttonMul.setForeground(new Color(255, 0, 0));
    buttonDiv = new JButton("/");
    buttonDiv.setForeground(new Color(255, 0, 0));
    buttonMod = new JButton("%");
    buttonMod.setForeground(new Color(0, 0, 255));
    buttonSqrt = new JButton("sqrt");
    buttonSqrt.setForeground(new Color(0, 0, 255));
    buttonDao = new JButton("1/x");
    buttonDao.setForeground(new Color(0, 0, 255));
    buttonEqual = new JButton("=");
    buttonEqual.setForeground(new Color(255, 0, 0));
    //將所有行為與監聽綁定
    panel3.setLayout(new GridLayout(4, 6));
    panel3.add(buttonMC);
    buttonMC.addActionListener(this);
    panel3.add(button[7]);
    button[7].addActionListener(this);
    panel3.add(button[8]);
    button[8].addActionListener(this);
    panel3.add(button[9]);
    button[9].addActionListener(this);
    panel3.add(buttonDiv);
    buttonDiv.addActionListener(this);
    panel3.add(buttonSqrt);
    buttonSqrt.addActionListener(this);
    panel3.add(buttonMR);
    buttonMR.addActionListener(this);
    panel3.add(button[4]);
    button[4].addActionListener(this);
    panel3.add(button[5]);
    button[5].addActionListener(this);
    panel3.add(button[6]);
    button[6].addActionListener(this);
    panel3.add(buttonMul);
    buttonMul.addActionListener(this);
    panel3.add(buttonMod);
    buttonMod.addActionListener(this);
    panel3.add(buttonMS);
    buttonMS.addActionListener(this);
    panel3.add(button[1]);
    button[1].addActionListener(this);
    panel3.add(button[2]);
    button[2].addActionListener(this);
    panel3.add(button[3]);
    button[3].addActionListener(this);
    panel3.add(buttonSub);
    buttonSub.addActionListener(this);
    panel3.add(buttonDao);
    buttonDao.addActionListener(this);
    panel3.add(buttonMAdd);
    buttonMAdd.addActionListener(this);
    panel3.add(button[0]);
    button[0].addActionListener(this);
    panel3.add(buttonAddAndSub);
    buttonAddAndSub.addActionListener(this);
    panel3.add(buttonDot);
    buttonDot.addActionListener(this);
    panel3.add(buttonAdd);
    buttonAdd.addActionListener(this);
    panel3.add(buttonEqual);
    buttonEqual.addActionListener(this);
    frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
    frame.pack();
    frame.show();
  }
  //設置各個按鈕行為
  public void actionPerformed(ActionEvent event) {
    boolean sign = false; //判斷是否是double型數參與運算，是為true，不是為false
    Object temp = event.getSource();
    try {
      //如果按下數據按鈕，將按下的按鈕代表的數據插入的當前文本框字符串之后
      for (int i = 0; i <= 9; i++)
        if (temp == button[i] && clickable == true)
          textAnswer.setText(textAnswer.getText() + Integer.toString(i));
          //按下'.'按鈕時，判斷當前文本框內字符串中含不含'.'，如果已含，則不允許再插入'.'
      if (temp == buttonDot && clickable == true) {
        boolean isDot = false;
        if (textAnswer.getText().length() == 0)
          isDot = true;
        for (int i = 0; i < textAnswer.getText().length(); i++)
          if ('.' == textAnswer.getText().charAt(i)) {
            isDot = true;
            break;
          }
        if (isDot == false)
          textAnswer.setText(textAnswer.getText() + ".");
      }
      if ( (temp == buttonAdd || temp == buttonSub || temp == buttonMul ||
            temp == buttonDiv) && clickable == true) {
        //'+'操作
        if (temp == buttonAdd) {
          switch (prekey) {
            case 0:
              answerd += Double.parseDouble(textAnswer.getText());
              break;
            case 1:
              answerd -= Double.parseDouble(textAnswer.getText());
              break;
            case 2:
              answerd *= Double.parseDouble(textAnswer.getText());
              break;
            case 3:
              if (Double.parseDouble(textAnswer.getText()) == 0) {
                textAnswer.setText("除數不能為零");
                clickable = false;
              }
              else
                answerd /= Double.parseDouble(textAnswer.getText());
              break;
            default:
              answerd = Double.parseDouble(textAnswer.getText());
          }
          textAnswer.setText("");
          prekey = key = 0;
        }
        //'-'操作
        if (temp == buttonSub) {
          switch (prekey) {
            case 0:
              answerd += Double.parseDouble(textAnswer.getText());
              break;
            case 1:
              answerd -= Double.parseDouble(textAnswer.getText());
              break;
            case 2:
              answerd *= Double.parseDouble(textAnswer.getText());
              break;
            case 3:
              if (Double.parseDouble(textAnswer.getText()) == 0) {
                textAnswer.setText("除數不能為零");
                clickable = false;
              }
              else
                answerd /= Double.parseDouble(textAnswer.getText());
              break;
            default:
              answerd = Double.parseDouble(textAnswer.getText());
          }
          textAnswer.setText("");
          prekey = key = 1;
        }
        //'*'操作
        if (temp == buttonMul) {
          switch (prekey) {
            case 0:
              answerd += Double.parseDouble(textAnswer.getText());
              break;
            case 1:
              answerd -= Double.parseDouble(textAnswer.getText());
              break;
            case 2:
              answerd *= Double.parseDouble(textAnswer.getText());
              break;
            case 3:
              if (Double.parseDouble(textAnswer.getText()) == 0) {
                textAnswer.setText("除數不能為零");
                clickable = false;
              }
              else
                answerd /= Double.parseDouble(textAnswer.getText());
              break;
            default:
              answerd = Double.parseDouble(textAnswer.getText());
          }
          textAnswer.setText("");