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());   }  } } 。

  。