Java利用Scanner 加Swich实现计算器

package base;

import java.util.Scanner;

public class Demo1 {
    
    
    public static void main(String[] args) {
    
    
        //System.out.println(f(5));
        Scanner a=new Scanner(System.in);
        double sum = 0;
        System.out.println("请输入第一个数字：");
        double num1=a.nextDouble();
        System.out.println("请输入第二个数字：");
        double num2=a.nextDouble();
        System.out.println("请输入运算符：");
        String op=a.next();
        switch (op){
    
    
            case "+":
                sum=num1+num2;
                System.out.println(num1+"+"+num2+"="+sum);
                break;
            case "-":
                sum=num1-num2;
                System.out.println(num1+"-"+num2+"="+sum);
                break;
            case "*":
                sum=num1*num2;
                System.out.println(num1+"*"+num2+"="+sum);
                break;
            case "/":
                sum=num1/num2;
                System.out.println(num1+"/"+num2+"="+sum);
                break;
        }

    }
    //阶乘问题
   /* public static int f(int n){
        if(n==1){
            return 1;
        }
        return n*(f(n-1));
    }*/

}

xinyue Day2