最近没事干，想起来原来上课时老师留过一个作业，就是做一个简单的计算器，实现简单的加减乘除功能，当时学的时候那是一个愁啊，最后也是不了了之了，很明显，不会做啊，今天闲了，突然想起来，应该做做试试吧，当然还是很顺利的，虽然格式规范什么的有点乱，但是功能还是可以实现的，当然由于处理逻辑较简单，只能实现两个数的四则运算，每次计算完后需要按“CE”将结果清除后重新输入。这里把代码共享出来，给刚学习java的童鞋做个参考:
下边是运行的界面：
1 package com.test.JPanel; 2 3 import java.awt.BorderLayout; 4 import java.awt.GridLayout; 5 import java.awt.event.ActionEvent; 6 import java.awt.event.ActionListener; 7 import javax.swing.JButton; 8 import javax.swing.JFrame; 9 import javax.swing.JPanel; 10 import javax.swing.JTextArea; 11 12 public class Calculator extends JFrame { 13 14 /** 15 * @param args 16 * @return 17 * @author zaj 18 * @since 2013/10/6 19 * @ 20 */ 21 JTextArea f1; 22 String s = ""; 23 String s2 = ""; 24 String a1; 25 Double sub1; 26 Double sub2; 27 String operator; 28 29 public class ButtonHandler implements ActionListener { 30 31 @Override 32 public void actionPerformed(ActionEvent e) { 33 // TODO Auto-generated method stub 34 if (!"CE".equals(e.getActionCommand()) 35 && !"=".equals(e.getActionCommand()) 36 && !"+".equals(e.getActionCommand()) 37 && !"-".equals(e.getActionCommand()) 38 && !"/".equals(e.getActionCommand()) 39 && !"*".equals(e.getActionCommand())) { 40 System.out.println("action occurred" + e.getActionCommand()); 41 a1 = e.getActionCommand(); 42 s = s + String.valueOf(a1); 43 if (s2.contains("+") || s2.contains("-") || s2.contains("*") 44 || s2.contains("/")) { 45 s2 = s2 + a1; 46 } 47 f1.append(a1); 48 } else if ("+".equals(e.getActionCommand())) { 49 sub1 = Double.parseDouble(s); 50 System.out.println(sub1); 51 52 s = s + e.getActionCommand(); 53 f1.append(e.getActionCommand() + "\n"); 54 s2 = s.substring(s.length() - 1); 55 operator = s2; 56 System.out.println("s2==========" + s2); 57 } else if ("-".equals(e.getActionCommand())) { 58 sub1 = Double.parseDouble(s); 59 System.out.println(sub1); 60 61 s = s + e.getActionCommand(); 62 f1.append(e.getActionCommand() + "\n"); 63 s2 = s.substring(s.length() - 1); 64 operator = s2; 65 System.out.println("s2==========" + s2); 66 } else if ("*".equals(e.getActionCommand())) { 67 sub1 = Double.parseDouble(s); 68 System.out.println(sub1); 69 70 s = s + e.getActionCommand(); 71 f1.append(e.getActionCommand() + "\n"); 72 s2 = s.substring(s.length() - 1); 73 operator = s2; 74 System.out.println("s2==========" + s2); 75 } else if ("/".equals(e.getActionCommand())) { 76 sub1 = Double.parseDouble(s); 77 System.out.println(sub1); 78 79 s = s + e.getActionCommand(); 80 f1.append(e.getActionCommand() + "\n"); 81 s2 = s.substring(s.length() - 1); 82 operator = s2; 83 System.out.println("s2==========" + s2); 84 } else if ("=".equals(e.getActionCommand())) { 85 s2 = s2.substring(1); 86 sub2 = Double.parseDouble(s2); 87 System.out.println(sub2); 88 Double result = 0.0; 89 if (operator.equals("+")) { 90 result = sub1 + sub2; 91 System.out.println(result); 92 } 93 if (operator.equals("-")) { 94 result = sub1 - sub2; 95 System.out.println(result); 96 } 97 if (operator.equals("*")) { 98 result = sub1 * sub2; 99 System.out.println(result);100 }101 if (operator.equals("/")) {102 result = sub1 / sub2;103 System.out.println(result);104 }105 106 f1.append("\n" + String.valueOf(result));107 108 } else if ("CE".equals(e.getActionCommand())) {109 110 System.out.println(e.getActionCommand());111 s = "";112 s2 = "";113 sub1 = 0.0;114 sub2 = 0.0;115 f1.setText("");116 }117 118 }119 120 }121 122 public Calculator() {123 setLayout(new BorderLayout());124 f1 = new JTextArea(3, 15);125 add(f1, "North");126 JPanel p1 = new JPanel();127 add(p1, "Center");128 129 p1.setLayout(new GridLayout(5, 4));130 JButton b1 = new JButton("1");131 JButton b2 = new JButton("2");132 JButton b3 = new JButton("3");133 JButton b4 = new JButton("4");134 JButton b5 = new JButton("5");135 JButton b6 = new JButton("6");136 JButton b7 = new JButton("7");137 JButton b8 = new JButton("8");138 JButton b9 = new JButton("9");139 JButton b10 = new JButton("+");140 JButton b11 = new JButton("-");141 JButton b12 = new JButton("*");142 JButton b13 = new JButton("0");143 JButton b14 = new JButton(".");144 JButton b15 = new JButton("=");145 JButton b16 = new JButton("/");146 JButton b17 = new JButton("CE");147 148 b1.addActionListener(new ButtonHandler());149 b2.addActionListener(new ButtonHandler());150 b3.addActionListener(new ButtonHandler());151 b4.addActionListener(new ButtonHandler());152 b5.addActionListener(new ButtonHandler());153 b6.addActionListener(new ButtonHandler());154 b7.addActionListener(new ButtonHandler());155 b8.addActionListener(new ButtonHandler());156 b9.addActionListener(new ButtonHandler());157 b10.addActionListener(new ButtonHandler());158 b11.addActionListener(new ButtonHandler());159 b12.addActionListener(new ButtonHandler());160 b13.addActionListener(new ButtonHandler());161 b14.addActionListener(new ButtonHandler());162 b15.addActionListener(new ButtonHandler());163 b16.addActionListener(new ButtonHandler());164 b17.addActionListener(new ButtonHandler());165 166 p1.add(b7);167 p1.add(b8);168 p1.add(b9);169 p1.add(b10);170 p1.add(b4);171 p1.add(b5);172 p1.add(b6);173 p1.add(b11);174 p1.add(b1);175 p1.add(b2);176 p1.add(b3);177 p1.add(b12);178 p1.add(b13);179 p1.add(b14);180 p1.add(b15);181 p1.add(b16);182 p1.add(b17);183 }184 185 public static void main(String[] args) {186 Calculator window = new Calculator();187 window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);188 window.setSize(480, 260);189 window.setTitle("Calculator-只能计算两数四则运算，使用完需要按“CE”清除");190 //window.pack();191 window.setVisible(true);192 }193 194 }