问题0

编写一个简单的计算器时出现的问题

package com.chen.caculator;

import java.util.Scanner;

public class Demo {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        String method = scanner.nextLine();//放到分割线后面程序就无法正常运行了 why？？？？？？？？
        double x1 = scanner.nextDouble();
        double x2 = scanner.nextDouble();
        System.out.println("==================");



        switch (method) {
            case "加法":
                System.out.println(add(x1, x2));
                break;
            case "减法":
                System.out.println(minus(x1, x2));
                break;
            case "乘法":
                System.out.println(multiply(x1, x2));
                break;
            case "除法":
                System.out.println(divide(x1, x2));
                break;

        }
        scanner.close();


    }

    public static double add(double x1, double x2) {
        return x1 + x2;
    }

    public static double minus(double x1, double x2) {
        return x1 - x2;
    }

    public static double multiply(double x1, double x2) {
        return x1 * x2;
    }

    public static double divide(double x1, double x2) {
        return x1 / x2;
    }
}