+-*/简单计算器

package com.tang.method;

import java.util.Scanner;

public class Demo06 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入计算规则:");
        String op =scanner.nextLine();
        System.out.println("请输入第一个数:");
        double a =scanner.nextDouble();
        //String x =scanner.nextLine();
        System.out.println("请输入第二个数：");
        double b =scanner.nextDouble();
        //String y =scanner.nextLine();
        switch (op){
            case "+":
                System.out.println("a+b= "+(a+b));
                break;
            case "-":
                System.out.println("a-b= "+(a-b));
                break;
            case "*":
                System.out.println("a*b= "+(a*b));
                break;
            case "/":
                System.out.println("a/b= "+(a/b));
                break;
            default:
                System.out.println("输入无效");
                scanner.close();
        }

    }
}