Java imitiert das Beispiel eines Windows-Rechners

Die Benutzeroberfläche dieses Rechners imitiert den einfachen Rechner, der mit Windows geliefert wird, einschließlich der interaktiven Benutzeroberfläche und der Reaktionen auf verschiedene Eingaben. Die Funktionen der Menüleiste und der Speicherschaltflächen wurden noch nicht implementiert

import java.awt.Color;
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.plaf.basic.BasicBorders;
public class Calculator extends JFrame {
 private static final long serialVersionUID = 1L;
 Container c = getContentPane();
 StringBuilder number1 = new StringBuilder("");// 储存第1个数字字符串
 StringBuilder number2 = new StringBuilder("");// 储存第2个数字字符串
 StringBuilder operator = new StringBuilder("");// 储存运算符
 StringBuilder result = new StringBuilder("");// 储存运算结果
 JTextField numbershow = new JTextField("0.");// 数字显示区域，初始显示为"0."
 public static void main(String[] args) {// 主方法
  Calculator c1 = new Calculator();
  c1.setVisible(true);
 }
 public Calculator() {// 计算器构造方法
  setTitle("计算器");
  setBounds(100, 100, 260, 245);
  setResizable(false);
  setLayout(null);
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  createMenuBar();// 创建菜单栏
  createNumberShow();// 创建数字显示区域
  createMemoShow();// 创建记忆显示
  createClearButtons();// 创建Backspace,CE,C等三个按钮
  createButtonArea();// 创建数字按钮区域
 }
 private void createMenuBar() {// 创建菜单栏的方法
  JMenuBar menubar = new JMenuBar();
  setJMenuBar(menubar);
  JMenu menu1 = new JMenu("编辑");
  JMenu menu2 = new JMenu("查看");
  JMenu menu3 = new JMenu("帮助");
  menubar.add(menu1);
  menubar.add(menu2);
  menubar.add(menu3);
  JMenuItem menu1item1 = new JMenuItem("复制");
  JMenuItem menu1item2 = new JMenuItem("粘贴");
  JMenuItem menu2item1 = new JMenuItem("标准型");
  JMenuItem menu2item2 = new JMenuItem("科学型");
  JMenuItem menu2item3 = new JMenuItem("科学分组");
  JMenuItem menu3item1 = new JMenuItem("帮助主题");
  JMenuItem menu3item2 = new JMenuItem("关于计算器");
  menu1.add(menu1item1);
  menu1.add(menu1item2);
  menu2.add(menu2item1);
  menu2.add(menu2item2);
  menu2.add(menu2item3);
  menu3.add(menu3item1);
  menu3.add(menu3item2);
 }
 private void createNumberShow() {// 创建数字显示区域的方法
  numbershow.setHorizontalAlignment(JTextField.RIGHT);
  numbershow.setBounds(5, 0, 245, 22);
  numbershow.setEnabled(false);
  numbershow.setDisabledTextColor(Color.BLACK);
  c.add(numbershow);
 }
 private void createMemoShow() {// 创建记忆显示的方法
  JTextField memoshow = new JTextField();
  memoshow.setEditable(false);
  memoshow.setBounds(10, 30, 28, 22);
  memoshow.setBorder(new BasicBorders.FieldBorder(Color.black,
    Color.black, Color.white, Color.white));
  c.add(memoshow);
 }
 private void createClearButtons() {// 创建Backspace,CE,C等三个按钮的方法
  JButton[] clearbutton = new JButton[3];
  String[] clearbuttontext = { "Backspace", "CE", "C" };
  for (int i = 0; i < 3; i++) {
   clearbutton[i] = new JButton();
   clearbutton[i].setText(clearbuttontext[i]);
   clearbutton[i].setHorizontalAlignment(SwingConstants.CENTER);
   clearbutton[i].setMargin(new Insets(0, 0, 0, 0));
   clearbutton[i].setFont(new java.awt.Font("Arial", 0, 9));
   clearbutton[i].setForeground(Color.blue);
   clearbutton[i].setBounds(48 + i * 68, 30, 63, 22);
   clearbutton[i].setForeground(Color.red);
   c.add(clearbutton[i]);
  }
  clearbutton[0].addActionListener(new ActionListener() {// 为Backspace按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      if (number1.toString().equals("")) {// 如果未做任何输入
       showNumber(numbershow, number1);// 显示number1
      } else if (operator.toString().equals("")) {// 如果只输入了number1
       number1.deleteCharAt(number1.toString().length() - 1);// 将number1的最后一个字符去掉
       showNumber(numbershow, number1);// 显示number1
      } else if (number2.toString().equals("")) {// 如果只输入了number1和operator
       showNumber(numbershow, number1);// 不作任何处理，显示number1
      } else {// 如果输入了number1、operator、number2
       number2.deleteCharAt(number2.toString().length() - 1);// 将number2的最后一个字符去掉
       showNumber(numbershow, number2);// 显示number2
      }
     }
    });
  clearbutton[1].addActionListener(new ActionListener() {// 为CE按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      if (number1.toString().equals("")) {// 如果未做任何输入
       showNumber(numbershow, number1);// 显示number1
      } else if (operator.toString().equals("")) {// 如果只输入了number1
       number1.setLength(0);// 清除number1
       showNumber(numbershow, number1);// 显示number1
      } else if (number2.toString().equals("")) {// 如果输入了number1和operator
       showNumber(numbershow, number2);// 不作任何处理，显示number2
      } else {// 如果输入了number1、operator、number2
       number2.setLength(0);// 清除number2
       showNumber(numbershow, number2);// 显示number2
      }
     }
    });
  clearbutton[2].addActionListener(new ActionListener() {// 为C按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {// 将所有储存清零
      number1.setLength(0);
      number2.setLength(0);
      operator.setLength(0);
      numbershow.setText("0.");
      result.setLength(0);
     }
    });
 }
 private void createButtonArea() {// 创建数字按钮区域的方法
  JPanel ButtonArea = new JPanel();
  ButtonArea.setBounds(5, 55, 245, 125);
  ButtonArea.setLayout(new GridLayout(4, 6, 5, 5));
  c.add(ButtonArea);
  JButton[] numberbutton = new JButton[24];
  String[] numberbuttontext = { "MC", "7", "8", "9", "/", "sqrt", "MR",
    "4", "5", "6", "*", "%", "MS", "1", "2", "3", "-", "1/X", "M+",
    "0", "+/-", ".", "+", "=" };
  for (int i = 0; i < 24; i++) {// 使用循环为这24个按钮添加标识
   numberbutton[i] = new JButton(numberbuttontext[i]);
   ButtonArea.add(numberbutton[i]);
   if (i % 6 == 0 || i % 6 == 4 || i == 23) {// 操作符按钮设置为红色
    numberbutton[i].setHorizontalAlignment(SwingConstants.CENTER);
    numberbutton[i].setMargin(new Insets(0, 0, 0, 0));
    numberbutton[i].setFont(new java.awt.Font("Arial", 0, 9));
    numberbutton[i].setForeground(Color.red);
   } else {// 其它设置为蓝色
    numberbutton[i].setHorizontalAlignment(SwingConstants.CENTER);
    numberbutton[i].setMargin(new Insets(0, 0, 0, 0));
    numberbutton[i].setFont(new java.awt.Font("Arial", 0, 9));
    numberbutton[i].setForeground(Color.blue);
   }
  }
  int[] numbers = { 19, 13, 14, 15, 7, 8, 9, 1, 2, 3 };// 该数组中的数字分别代表0-9等数字在numberbuttontext数组中序号
  for (int i = 0; i <= 9; i++) { // 使用循环为这0-9这十个数字按钮添加监听器
   final String str = String.valueOf(i);
   numberbutton[numbers[i]].addActionListener(new ActionListener() {// 为0-9按钮添加监听器
      @Override
      public void actionPerformed(ActionEvent e) {
       if (operator.toString().equals("")) {// 没有输入operator之前
        add(number1, str); // 只设置number1的值
        showNumber(numbershow, number1);// 只显示number1的值
       } else {// 输入operator之后
        add(number2, str);// 只设置number2的值
        showNumber(numbershow, number2);// 只显示number2的值
       }
      }
     });
  }
  numberbutton[20].addActionListener(new ActionListener() { // 为"+/-"按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      if (operator.toString().equals("")) {// 没有输入operator之前
       add(number1, "+/-");// 只设置number1的值
       showNumber(numbershow, number1);// 只显示number1的值
      } else {// 输入operator之后
       add(number2, "+/-");// 只设置number2的值
       showNumber(numbershow, number2);// 只显示number2的值
      }
     }
    });
  numberbutton[21].addActionListener(new ActionListener() { // 为"."按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      if (operator.toString().equals("")) {// 在输入operator之前，只显示number1的值
       add(number1, ".");
       showNumber(numbershow, number1);
      } else {// 在输入operator之后，只显示number2的值
       add(number2, ".");
       showNumber(numbershow, number2);
      }
     }
    });
  numberbutton[22].addActionListener(new ActionListener() { // 为"+"按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      operator.setLength(0);
      operator.append("+");
     }
    });
  numberbutton[16].addActionListener(new ActionListener() { // 为"-"按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      operator.setLength(0);
      operator.append("-");
     }
    });
  numberbutton[10].addActionListener(new ActionListener() { // 为"*"按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      operator.setLength(0);
      operator.append("*");
     }
    });
  numberbutton[4].addActionListener(new ActionListener() { // 为"/"按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      operator.setLength(0);
      operator.append("/");
     }
    });
  numberbutton[23].addActionListener(new ActionListener() { // 为"="按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      if (number1.toString().equals("")) {// 当number1为空时
       showNumber(numbershow, number1);
      } else if (operator.toString().equals("")) {// 当number1不为空，而operator为空时
       showNumber(numbershow, number1);
      } else if (number2.toString().equals("")) {// 当number1、operator均不为空，而number2为空时
       switch (operator.toString()) {
       case ("+"): {
        number2.append(number1.toString());
        double d = Double.parseDouble(number1
          .toString())
          + Double.parseDouble(number2.toString());
        result.setLength(0);
        result.append(d);
        showNumber(numbershow, result);
        number1.setLength(0);
        number1.append(d);
       }
        break;
       case ("-"): {
        number2.append(number1.toString());
        double d = Double.parseDouble(number1
          .toString())
          - Double.parseDouble(number2.toString());
        result.setLength(0);
        result.append(d);
        showNumber(numbershow, result);
        number1.setLength(0);
        number1.append(d);
       }
        break;
       case ("*"): {
        number2.append(number1.toString());
        double d = Double.parseDouble(number1
          .toString())
          * Double.parseDouble(number2.toString());
        result.setLength(0);
        result.append(d);
        showNumber(numbershow, result);
        number1.setLength(0);
        number1.append(d);
       }
        break;
       case ("/"): {
        number2.append(number1.toString());
        double d = Double.parseDouble(number1
          .toString())
          / Double.parseDouble(number2.toString());
        result.setLength(0);
        result.append(d);
        showNumber(numbershow, result);
        number1.setLength(0);
        number1.append(d);
       }
        break;
       }
      } else {// 当number1、operator、number2均不为空时
       switch (operator.toString()) {
       case ("+"): {
        double d = Double.parseDouble(number1
          .toString())
          + Double.parseDouble(number2.toString());
        result.setLength(0);
        result.append(d);
        showNumber(numbershow, result);
        number1.setLength(0);
        number1.append(d);
       }
        break;
       case ("-"): {
        double d = Double.parseDouble(number1
          .toString())
          - Double.parseDouble(number2.toString());
        result.setLength(0);
        result.append(d);
        showNumber(numbershow, result);
        number1.setLength(0);
        number1.append(d);
       }
        break;
       case ("*"): {
        double d = Double.parseDouble(number1
          .toString())
          * Double.parseDouble(number2.toString());
        result.setLength(0);
        result.append(d);
        showNumber(numbershow, result);
        number1.setLength(0);
        number1.append(d);
       }
        break;
       case ("/"): {
        double d = Double.parseDouble(number1
          .toString())
          / Double.parseDouble(number2.toString());
        result.setLength(0);
        result.append(d);
        showNumber(numbershow, result);
        number1.setLength(0);
        number1.append(d);
       }
        break;
       }
      }
     }
    });
  numberbutton[17].addActionListener(new ActionListener() { // 为"1/x"按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      if (number1.toString().equals("")) {// 没有输入number1时
       numbershow.setText("除数不能为零");
      } else if (operator.toString().equals("")) {// 输入了number1，但没有输入operator
       if (Double.parseDouble(number1.toString()) == 0) {// 如果number1的值为零
        numbershow.setText("除数不能为零");
       } else {// 如果number1的值不为零
        double d = 1 / (Double.parseDouble(number1
          .toString()));
        number1.setLength(0);
        number1.append(d);// 将number1的值开放并存储
        showNumber(numbershow, number1);
       }
      } else if (number2.toString().equals("")) {// 输入了number1、operator，但没有输入number2
       double d = 1 / (Double.parseDouble(number1
         .toString()));
       number2.append(d);// 将number1的值开放并存储
       showNumber(numbershow, number2);
      } else {// 输入了number1、operator，number2
       double d = 1 / (Double.parseDouble(number2
         .toString()));
       number2.setLength(0);
       number2.append(d);// 将number2的值开放并存储
       showNumber(numbershow, number2);
      }
     }
    });
  numberbutton[11].addActionListener(new ActionListener() { // 为"%"按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      // 暂时空缺
     }
    });
  numberbutton[5].addActionListener(new ActionListener() { // 为"sqrt"按钮添加监听器
     @Override
     public void actionPerformed(ActionEvent e) {
      if (number1.toString().equals("")) {// 没有输入number1时
       showNumber(numbershow, number1);
      } else if (operator.toString().equals("")) {// 输入了number1，但没有输入operator
       if (Double.parseDouble(number1.toString()) < 0) {// number1小于0
        numbershow.setText("函数输入无效");
       } else {// number1大于0
        double d = Math.sqrt(Double.parseDouble(number1
          .toString()));
        number1.setLength(0);
        number1.append(d);// 将number1的值开放并存储
        showNumber(numbershow, number1);
       }
      } else if (number2.toString().equals("")) {// 输入了number1、operator，但没有输入number2
       double d = Math.sqrt(Double.parseDouble(number1
         .toString()));
       number2.append(d);// 将number1的值开放并存储
       showNumber(numbershow, number2);
      } else {// 输入了number1、operator、number2
       double d = Math.sqrt(Double.parseDouble(number2
         .toString()));
       number2.setLength(0);
       number2.append(d);// 将number2的值开放并存储
       showNumber(numbershow, number2);
      }
     }
    });
 }
 public void add(StringBuilder s1, String s2) {// 定义按钮输入后数字字符串变化的方法
  if (s2.equals("+/-")) {// 定义输入"+/-"后数字字符串的变化
   if (s1.toString().equals("") || s1.toString().equals("0")) {// 如果数字字符串为空或者0，那么不发生变化
    s1.append("");
   } else {// 如果数字字符串不为空也不为0，那么在数字字符串前增加或删除"-"字符
    if (s1.toString().startsWith("-")) {
     s1.deleteCharAt(0);
    } else {
     s1.insert(0, "-");
    }
   }
  }
  if (s2.equals(".")) {// 定义输入"."后数字字符串的变化
   if (s1.toString().indexOf(".") == -1) {// 查找数字字符串中是否含有"."字符，如果没有则执行以下代码
    if (s1.toString().equals("")) {// 如果数字字符串为空，那么将数字字符串设置为"0."
     s1.setLength(0);
     s1.append("0.");
    } else {
     s1.append(".");
    }
   } else {// 如果有，则不发生变化
    s1.append("");
   }
  }
  if (s2.equals("0")) {// 定义输入"0"后数字字符串的变化
   if (s1.toString().equals("0")) {// 当数字的字符串为"0"时，不发生变化
    s1.append("");
   } else {// 当数字的字符串吧为"0"时，在其字符串后增加"0"
    s1.append("0");
   }
  }
  for (int i = 1; i < 10; i++) {// 通过循环，定义输入1-9后数字字符串的变化
   String str = String.valueOf(i);
   if (s2.equals(str)) {// 定义输入1-9后数字字符串的变化
    if (s1.toString().equals("0")) {
     s1.setLength(0);
     s1.append(str);
    } else
     s1.append(str);
   }
  }
 }
 public void showNumber(JTextField j, StringBuilder s) {// 定义数字显示区域如何显示数字字符串的方法
  if (s.toString().equals("") == true || s.toString().equals("0") == true) {
   j.setText("0.");
  } else if (s.toString().indexOf(".") == -1) {
   j.setText(s.toString() + ".");
  } else {
   j.setText(s.toString());
  }
 }
}

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