21-简易计算器

package com.wang.mothod;

import java.util.Scanner;

public class Demo01 {
    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        System.out.print("请输入第一个数字：");
        double num1=scanner.nextDouble();
        System.out.print("请输入运算符：");
        String operator=scanner.next();
        System.out.print("请输入第二个数字：");
        double num2=scanner.nextDouble();

        switch (operator){
            case "+":
                System.out.println(num1+"+"+num2+"="+method1(num1,num2));
                break;
            case "-":
                System.out.println(num1+"-"+num2+"="+method2(num1,num2));
                break;
            case "*":
                System.out.println(num1+"*"+num2+"="+method3(num1,num2));
                break;
            case "/":
                if(num2==0){
                    System.out.println("ERROR");
                }else {
                    System.out.println(num1 + "/" + num2 + "=" + method4(num1, num2));
                }
                break;
            default:
                System.out.println("输入错误");
        }
        scanner.close();
    }

//新建4种方法
    public static double method1(double x,double y){
        return x+y;
    }
    public static double method2(double x,double y){
        return x-y;
    }
    public static double method3(double x,double y){
        return x*y;
    }
    public static double method4(double x,double y){
        return x/y;
    }
}