switch case实现两个数的算术运算

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方法一：

package com.liaojianya.chapter1;import java.util.Scanner;public class SwitchDemo1{public static void main(String[] args){Scanner input = new Scanner(System.in);System.out.println("Enter number a : ");double a = input.nextDouble();System.out.println("Enter number b : ");double b = input.nextDouble();Action ac = new Action(a, b);ac.command(Action.ADD);ac.command(Action.SUBTRACT);ac.command(Action.MULTIPLY);ac.command(Action.DIVIDE);ac.command(Action.MOD);input.close();}}class Action{double a;double b;public Action(double a, double b){this.a = a;this.b = b;}public static final int ADD = 1;public static final int SUBTRACT = 2;public static final int MULTIPLY = 3;public static final int DIVIDE = 4;public static final int MOD = 5;public void command(int c){switch (c){case 1:System.out.println(a + " + " + b + " = " + (a + b));break;case 2:System.out.println(a + " - " + b + " = " + (a - b));break;case 3:System.out.println(a + " * " + b + " = " + (a * b));break;case 4:System.out.println(a + " / " + b + " = " + (a / b));break;case 5:System.out.println(a + " % " + b + " = " + (a % b));break;default:System.out.println("unknown operation!");break;}}}

　　方法二：

package com.liaojianya.chapter1;import java.util.Scanner;/** * This program demonstrates the use of switch. * @author LIAO JIANYA * */public class SwitchDemo{public static void main(String[] args){Scanner input = new Scanner(System.in);System.out.println("Enter number a : ");double a = input.nextDouble();System.out.println("Enter number b : ");double b = input.nextDouble();System.out.println("Enter  operater :1代表+，2代表-，3代表*，4代表/，5代表% ");int c = input.nextInt();switch(c){case 1:System.out.println(a + " + " + b + " = " + (a + b));break;case 2:System.out.println(a + " - " + b + " = " + (a - b));break;case 3:System.out.println(a + " * " + b + " = " + (a * b));break;case 4:System.out.println(a + " / " + b + " = " + (a / b));break;case 5:System.out.println(a + " % " + b + " = " + (a % b));break;default:System.out.println("unknown operation!");break;}}}

　　运行结果：

Enter number a : 12.3Enter number b : 32.112.3 + 32.1 = 44.40000000000000612.3 - 32.1 = -19.812.3 * 32.1 = 394.8300000000000412.3 / 32.1 = 0.3831775700934579312.3 % 32.1 = 12.3

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