1 import java.util.Scanner; 2 3 public class CaculationTest { 4 5 public static void main(String[] args) { 6 7 Scanner reader = new Scanner(System.in); 8 double a, b, result = 0; 9 String operator; 10 Operation operation = null; 11 12 System.out.println("************************"); 13 System.out.println("* 学号:1308060310 *"); 14 System.out.println("* 班级:网络131班 *"); 15 System.out.println("* 姓名:王朝远 *"); 16 System.out.println("************************"); 17 18 TwoFromConsole twoFromConsole = new TwoFromConsole(); 19 a = twoFromConsole.getFirstDoubleFromConsole(); // 获取第一个数 20 b = twoFromConsole.getTwoDoubleFromConsole(); // 获取第二个数 21 22 OperatorFromConsole operatorFromConsole = new OperatorFromConsole(); 23 operator = operatorFromConsole.getOperator(); // 获取运算符号 24 do { 25 if (operator.equals("/") && b == 0) { 26 System.out.print("除法运算分母不能为0,请重新输入,"); 27 b = twoFromConsole.getTwoDoubleFromConsole(); // 获取第二个数 28 continue; 29 } 30 break; 31 } while (true); 32 33 // 获取要运算的对象 34 operation = Factory.getInstance(operator); 35 result = operation.getResult(a, b); 36 37 // 判断用户是否继续对数运算,如果是继续对数运算,结果的输出方式就不一样,并且让用户选择是否再次计算 38 if (operator.equals("log")) { 39 40 System.out.println("log" + "(" + b + ")" + a + "=" + result); 41 } else { 42 System.out.println(a + operator + b + "=" + result); 43 } 44 } 45 } 46 47 class TwoFromConsole { 48 49 Scanner reader = new Scanner(System.in); 50 51 // 获取数字的方法的具体实现 52 public double getFirstDoubleFromConsole() { 53 54 double x = 0; 55 System.out.print("请输入第一个数字:"); 56 do { 57 double temp = 0; 58 try { 59 temp = reader.nextDouble(); 60 } catch (Exception e) { 61 System.out.print("请重新输入第一个数字:"); 62 continue; 63 } 64 x = temp; 65 break; 66 } while (true); 67 return x; 68 } 69 70 public double getTwoDoubleFromConsole() { 71 72 double x = 0; 73 System.out.print("请输入第二个数字:"); 74 do { 75 double temp = 0; 76 try { 77 temp = reader.nextDouble(); 78 } catch (Exception e) { 79 System.out.print("请重新输入第二个数字:"); 80 continue; 81 } 82 x = temp; 83 break; 84 } while (true); 85 return x; 86 } 87 } 88 89 /** 90 * 获取运算符类 91 */ 92 class OperatorFromConsole { 93 94 Scanner reader = new Scanner(System.in); 95 96 /** 97 * @return 合理的运算符 98 */ 99 public String getOperator() { 100 System.out.print("请输入运算符:"); 101 102 String operator; 103 boolean b; 104 do { 105 operator = reader.nextLine(); 106 b = !(operator.equals("+") || operator.equals("-") || operator.equals("*") || operator.equals("/") 107 || operator.equals("log")); 108 if (b == true) { 109 System.out.print("请重新输入运算符:"); 110 } 111 } while (b); 112 113 return operator; 114 } 115 } 116 117 /** 118 * 功能:各个运算的父接口,子类必须实现父接口里面的方法 119 */ 120 interface Operation { 121 122 double getResult(double x, double y); 123 } 124 125 /** 126 * 实现加法运算的类 127 */ 128 class Add implements Operation { 129 130 /** 131 * 重写接口里面的方法,并实现加法功能 132 */ 133 @Override 134 public double getResult(double x, double y) { 135 // TODO Auto-generated method stub 136 return x + y; 137 } 138 139 } 140 141 /** 142 * 实现减法运算的类 143 */ 144 class Sub implements Operation { 145 146 /** 147 * 重写接口里面的方法,并实现减法功能 148 */ 149 @Override 150 public double getResult(double x, double y) { 151 // TODO Auto-generated method stub 152 return x - y; 153 } 154 } 155 156 /** 157 * 实现乘法运算的类 158 */ 159 class Mul implements Operation { 160 161 /** 162 * 重写接口里面的方法,并实现乘法功能 163 */ 164 @Override 165 public double getResult(double x, double y) { 166 // TODO Auto-generated method stub 167 return x * y; 168 } 169 170 } 171 172 /** 173 * 实现除法运算的类 174 */ 175 class Div implements Operation { 176 177 /** 178 * 重写接口里面的方法,并实现除法功能 179 */ 180 @Override 181 public double getResult(double x, double y) { 182 // TODO Auto-generated method stub 183 return x / y; 184 } 185 186 } 187 188 /** 189 * 实现对数运算的类 190 */ 191 class Logarithm implements Operation { 192 193 /** 194 * 重写接口里面的方法,并实现对数运算功能 195 */ 196 @Override 197 public double getResult(double x, double y) { 198 // TODO Auto-generated method stub 199 return Math.log(x) / Math.log(y); // x表示对数,y表示底数 200 } 201 202 } 203 204 /** 205 * 生成用户所需要的对象工厂类 206 */ 207 class Factory { 208 209 /** 210 * @param operator 211 * 用户选择的运算 212 * @return 用户所需要的对象 213 */ 214 public static Operation getInstance(String operator) { 215 Operation operation = null; 216 switch (operator) { 217 case "+": 218 operation = new Add(); // 实例化加法对象 219 break; 220 case "-": 221 operation = new Sub(); // 实例化减法对象 222 break; 223 case "*": 224 operation = new Mul(); // 实例化乘法对象 225 break; 226 case "/": 227 operation = new Div(); // 实例化除法对象 228 break; 229 case "log": 230 operation = new Logarithm(); // 实例化对数运算对象 231 break; 232 } 233 234 return operation; 235 } 236 }