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() + " "); 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() + " "); 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() + " "); 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() + " "); 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(" " + 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 }