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java 简易计算器_java计算器

作者：小蓝xlanll | 2024-03-20 18:48:37

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java计算器

要求：

1.使用Java图形界面组件设计软件，界面如图所示。

2.软件能够满足基本的“加、减、乘、除”等运算要求。

3.程序代码清晰，语法规范，结构合理，逻辑正确。

效果图：

2b9091ad8bc94af0b2f3af902ac72003.png

先分析，计算器大概是由三个大部分组成的：菜单栏，显示框，按钮。

所以定义一个类cal继承JFrame。

  1. class cal extends JFrame  {
  2.     private JPanel p1, p2;
  3.     private JTextArea show;
  4.     private String box ;
  5.     JMenuBar menubar;//菜单
  6.     JMenu menu1, menu2, menu3;//菜单
  7.  
  8.     StringBuffer strA;//用来存放用户输入的第一个数字
  9.     StringBuffer strB;//用来存放用户输入的第二个数字
  10.  
  11. char oper ='~';//初始化操作符，可以随便初始化一个特殊符号，这里只是用来区分的
  12.     double  A;
  13.     double  B;
  14.     private String[] text2 = {"C", "CE","%", "/",
  15.             "7", "8", "9", "*",
  16.             "4", "5", "6", "-",
  17.             "1", "2", "3", "+",
  18.             "DEL","0", ".", "="};//计算器按钮面板
  19.  
  20.     private JButton[] munButton = new JButton[text2.length];
  21.  
  22.  
  23. }

我们定义完后开始初始化。

  1. class cal extends JFrame implements ActionListener {
  2.     private JPanel p1, p2;
  3.     private JTextArea show;
  4.     private String box ;
  5.     JMenuBar menubar;
  6.     JMenu menu1, menu2, menu3;
  7.     StringBuffer strA;
  8.     StringBuffer strB;
  9.  
  10.  
  11.  
  12.     char oper ='~';
  13.     double  A;
  14.     double  B;
  15.     private String[] text2 = {"C", "CE","%", "/",
  16.             "7", "8", "9", "*",
  17.             "4", "5", "6", "-",
  18.             "1", "2", "3", "+",
  19.             "DEL","0", ".", "="};//计算器按钮面板
  20.     private JButton[] munButton = new JButton[text2.length];
  21.  
  22.  
  23.  
  24.  
  25.  
  26.     public cal() {
  27.         p1 = new JPanel();
  28.         p2 = new JPanel();
  29.         show = new JTextArea();
  30.         p1.setSize(600, 100);
  31.         menubar = new JMenuBar();
  32.         menu1 = new JMenu("查看(V)");
  33.         menu2 = new JMenu("编辑(E)");
  34.         menu3 = new JMenu("帮助(H)");
  35.  
  36.         strB=new StringBuffer();
  37.         strA=new StringBuffer();
  38.  
  39.  
  40.     }
  41.  
  42.  
  43.  
  44.     public void init() {//初始化
  45.         this.setTitle("计算器");//设置名称
  46.         this.setBounds(200, 200, 320, 300);
  47.  
  48.         this.setLayout(new BorderLayout());//设置布局
  49.  
  50.         this.add(p1, BorderLayout.CENTER);
  51.         this.add(p2, BorderLayout.SOUTH);
  52.         menubar.add(menu1);
  53.         menubar.add(menu2);
  54.         menubar.add(menu3);
  55.         this.setJMenuBar(menubar);
  56.         this.setLocationRelativeTo(null);//放置在屏幕中央
  57.         this.setResizable(false);//固定大小，用户不能调整大小
  58.  
  59.         show.setPreferredSize(new Dimension(300, 100));
  60.         p1.add(show);
  61.         p2.setLayout(new GridLayout(5, 4, 2, 3));
  62.         //添加数字按键
  63.         for (int i = 0; i < text2.length; i++) {
  64.             munButton[i] = new JButton(text2[i] + " ");
  65.             p2.add(munButton[i]);
  66.         }
  67.  
  68.  
  69.  
  70.         for (int i = 0; i < munButton.length; i++)
  71.             munButton[i].addActionListener(this);
  72.  
  73.         this.setVisible(true);//窗体可视化
  74.  
  75.  
  76.         this.addWindowListener(new WindowAdapter() {//监听事件，当按下关闭按钮时，结束程序
  77.  
  78.             @Override
  79.             public void windowClosing(WindowEvent e) {
  80.                 System.exit(0);
  81.             }
  82.         });
  83.  
  84.     }

接着我们就开始进入到这个项目的最重要的部分了。

设置按钮监听事件，通过获取按钮的信息来进行判断运算。

在我们进行加减乘除计算的时候会出现一个特殊情况，除数为0，所以我们要预防出现异常影响程序的运行，我们就要进行异常的捕获处理，这里我是自定义了一个异常类munber_Exception，然后我们利用try｛｝catch｛｝语句来进行异常捕获和处理。

  1.     public double division(double x,double y)throws munber_Exception{
  2.  
  3.         if(y==0){
  4.             throw new munber_Exception("除数不能为0！");
  5.         }
  6.         else{
  7.             return x/y;
  8.         }
  9.  
  10.  
  11.     }
  12.     @Override
  13.     public void actionPerformed(ActionEvent e) {
  14.         try { String act=e.getActionCommand();//这个方法返回的是事件源组件的“命令” ， 这个“命令” 实际上就是事件源组件上的“Label（标签）字符串”，即如果我按了“9”这个按钮他就会返回一个“9的值”
  15.  
  16.         char a=act.charAt(0);//取act这个字符串的首字符
  17.         if (a=='0' ||a=='1' || a=='2' ||a=='3'||a=='4'||a=='5'||a=='6'||a=='7'||a=='8'||a=='9'||a=='.') {
  18.             if(oper=='~'){//当oper=='~'时，则操作符为空
  19.                 strA.append(a);
  20.                 show.setText(String.valueOf(strA));
  21.  
  22.  
  23.             }else {
  24.                 strB.append(a);
  25.                 show.setText(String.valueOf(strA)+oper+String.valueOf(strB));
  26.  
  27.  
  28.             }
  29.  
  30.         }
  31.         else if(a=='+'||a=='-'||a=='/'||a=='*'||a=='%'){
  32.             oper=a;
  33.             show.setText(String.valueOf(strA)+oper);
  34.  
  35.         }
  36.         else if(a=='='){
  37.  
  38.                A = Double.parseDouble(String.valueOf(strA));
  39.                B = Double.parseDouble(String.valueOf(strB));
  40.                double j;
  41.                 int len1=strA.length();
  42.                 int len2=strB.length();
  43.  
  44.                if (oper == '+') {
  45.                    j = A + B;
  46.                    show.setText(Double.toString(j));
  47.  
  48.                    strA.delete(0,len1);
  49.                    strB.delete(0,len2);
  50.                    strA.append(j);
  51.  
  52.                } else if (oper == '-') {
  53.                    j = A - B;
  54.                    show.setText(Double.toString(j));
  55.  
  56.                    strA.delete(0,len1);
  57.                    strB.delete(0,len2);
  58.                    strA.append(j);
  59.                } else if (oper == '*') {
  60.                    j = A * B;
  61.                    show.setText(Double.toString(j));
  62.  
  63.                    strA.delete(0,len1);
  64.                    strB.delete(0,len2);
  65.                    strA.append(j);
  66.                } else if (oper == '/') {
  67.                    try{j= division(A, B);}catch(munber_Exception u){
  68.                        show.setText(u.shows());
  69.                    }
  70.                }
  71.                else if (oper == '%') {
  72.                    j = A % B;
  73.                    show.setText(Double.toString(j));
  74.  
  75.                    strA.delete(0,len1);
  76.                    strB.delete(0,len2);
  77.                    strA.append(j);
  78.  
  79.                }
  80.  
  81.  
  82.  
  83.         } else if (a=='C') {//清除
  84.             show.setText(" ");
  85.             oper='~';
  86.             int len1=strA.length();
  87.             int len2=strB.length();
  88.  
  89.             strA.delete(0,len1);
  90.             strB.delete(0,len2);
  91.  
  92.         } else if (a=='D'){//删除
  93.                  if(oper!='~'){
  94.                      if(strB.length()>0){
  95.                          strB.delete(strB.length()-1,strB.length());
  96.                          show.setText(String.valueOf(strA)+oper+String.valueOf(strB));
  97.                      }
  98.                      else
  99.                          show.setText("0");
  100.                  }if(oper=='~'){
  101.                      if(strA.length()>0){
  102.                          strA.delete(strA.length()-1,strA.length());
  103.                          show.setText(String.valueOf(strA));
  104.                      }
  105.             }
  106.         }   }catch(ArithmeticException m){
  107.         System.out.println("除数不能为0");
  108.     }
  109.  
  110.     }

完整代码如下：

  1. class munber_Exception  extends Exception{  //异常处理
  2.     String e;
  3.     public munber_Exception(){
  4.  
  5.     }
  6.     public munber_Exception(String message){
  7.         this.e=message;
  8.     }
  9.     public String shows(){
  10.         return e;
  11.  
  12.     }
  13. }
  14.  
  15. class cal extends JFrame implements ActionListener {
  16.     private JPanel p1, p2;
  17.     private JTextArea show;
  18.     private String box ;
  19.     JMenuBar menubar;
  20.     JMenu menu1, menu2, menu3;
  21.     StringBuffer strA;
  22.     StringBuffer strB;
  23.  
  24.  
  25.  
  26.     char oper ='~';
  27.     double  A;
  28.     double  B;
  29.     private String[] text2 = {"C", "CE","%", "/",
  30.             "7", "8", "9", "*",
  31.             "4", "5", "6", "-",
  32.             "1", "2", "3", "+",
  33.             "DEL","0", ".", "="};//计算器按钮面板
  34.     private JButton[] munButton = new JButton[text2.length];
  35.  
  36.     public cal() {
  37.         p1 = new JPanel();
  38.         p2 = new JPanel();
  39.         show = new JTextArea();
  40.         p1.setSize(600, 100);
  41.         menubar = new JMenuBar();
  42.         menu1 = new JMenu("查看(V)");
  43.         menu2 = new JMenu("编辑(E)");
  44.         menu3 = new JMenu("帮助(H)");
  45.  
  46.         strB=new StringBuffer();
  47.         strA=new StringBuffer();
  48.  
  49.  
  50.     }
  51.  
  52.  
  53.  
  54.     public void init() {//初始化
  55.         this.setTitle("计算器");
  56.         this.setBounds(200, 200, 320, 300);
  57.  
  58.         this.setLayout(new BorderLayout());
  59.  
  60.         this.add(p1, BorderLayout.CENTER);
  61.         this.add(p2, BorderLayout.SOUTH);
  62.         menubar.add(menu1);
  63.         menubar.add(menu2);
  64.         menubar.add(menu3);
  65.         this.setJMenuBar(menubar);
  66.         this.setLocationRelativeTo(null);
  67.         this.setResizable(false);
  68.  
  69.         show.setPreferredSize(new Dimension(300, 100));
  70.         p1.add(show);
  71.         p2.setLayout(new GridLayout(5, 4, 2, 3));
  72.         //添加数字按键
  73.         for (int i = 0; i < text2.length; i++) {
  74.             munButton[i] = new JButton(text2[i] + " ");
  75.             p2.add(munButton[i]);
  76.         }
  77.  
  78.  
  79.  
  80.         for (int i = 0; i < munButton.length; i++)
  81.             munButton[i].addActionListener(this);
  82.  
  83.         this.setVisible(true);
  84.  
  85.  
  86.         this.addWindowListener(new WindowAdapter() {
  87.             @Override
  88.             public void windowClosing(WindowEvent e) {
  89.                 System.exit(0);
  90.             }
  91.         });
  92.  
  93.     }
  94.  
  95.  
  96.     public double division(double x,double y)throws munber_Exception{
  97.  
  98.         if(y==0){
  99.             throw new munber_Exception("除数不能为0！");
  100.         }
  101.         else{
  102.             return x/y;
  103.         }
  104.  
  105.  
  106.     }
  107.     @Override
  108.     public void actionPerformed(ActionEvent e) {
  109.         try { String act=e.getActionCommand();
  110.         char a=act.charAt(0);
  111.         if (a=='0' ||a=='1' || a=='2' ||a=='3'||a=='4'||a=='5'||a=='6'||a=='7'||a=='8'||a=='9'||a=='.') {
  112.             if(oper=='~'){
  113.                 strA.append(a);
  114.                 show.setText(String.valueOf(strA));
  115.  
  116.  
  117.             }else {
  118.                 strB.append(a);
  119.                 show.setText(String.valueOf(strA)+oper+String.valueOf(strB));
  120.  
  121.  
  122.             }
  123.  
  124.         }
  125.         else if(a=='+'||a=='-'||a=='/'||a=='*'||a=='%'){
  126.             oper=a;
  127.             show.setText(String.valueOf(strA)+oper);
  128.  
  129.         }
  130.         else if(a=='='){
  131.  
  132.                A = Double.parseDouble(String.valueOf(strA));
  133.                B = Double.parseDouble(String.valueOf(strB));
  134.                double j;
  135.                 int len1=strA.length();
  136.                 int len2=strB.length();
  137.  
  138.                if (oper == '+') {
  139.                    j = A + B;
  140.                    show.setText(Double.toString(j));
  141.  
  142.                    strA.delete(0,len1);
  143.                    strB.delete(0,len2);
  144.                    strA.append(j);
  145.  
  146.                } else if (oper == '-') {
  147.                    j = A - B;
  148.                    show.setText(Double.toString(j));
  149.  
  150.                    strA.delete(0,len1);
  151.                    strB.delete(0,len2);
  152.                    strA.append(j);
  153.                } else if (oper == '*') {
  154.                    j = A * B;
  155.                    show.setText(Double.toString(j));
  156.  
  157.                    strA.delete(0,len1);
  158.                    strB.delete(0,len2);
  159.                    strA.append(j);
  160.                } else if (oper == '/') {
  161.                    try{j= division(A, B);}catch(munber_Exception u){
  162.                        show.setText(u.shows());
  163.                    }
  164.                }
  165.                else if (oper == '%') {
  166.                    j = A % B;
  167.                    show.setText(Double.toString(j));
  168.  
  169.                    strA.delete(0,len1);
  170.                    strB.delete(0,len2);
  171.                    strA.append(j);
  172.  
  173.                }
  174.  
  175.  
  176.  
  177.         } else if (a=='C') {
  178.             show.setText(" ");
  179.             oper='~';
  180.             int len1=strA.length();
  181.             int len2=strB.length();
  182.  
  183.             strA.delete(0,len1);
  184.             strB.delete(0,len2);
  185.  
  186.         } else if (a=='D'){
  187.                  if(oper!='~'){
  188.                      if(strB.length()>0){
  189.                          strB.delete(strB.length()-1,strB.length());
  190.                          show.setText(String.valueOf(strA)+oper+String.valueOf(strB));
  191.                      }
  192.                      else
  193.                          show.setText("0");
  194.                  }if(oper=='~'){
  195.                      if(strA.length()>0){
  196.                          strA.delete(strA.length()-1,strA.length());
  197.                          show.setText(String.valueOf(strA));
  198.                      }
  199.             }
  200.         }   }catch(ArithmeticException m){
  201.         System.out.println("除数不能为0");
  202.     }
  203.  
  204.     }
  205. }
  206.  
  207. public class Calculator {
  208. //调用
  209.     public static void main(String[] args) {
  210.       cal Calculator1 = new cal();
  211.         Calculator1.init();
  212. }
  213.  
  214.     }
 

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