Java学习之路--method--加减乘除的实现

package com.chao.method;

import java.util.Scanner;

//加、减、乘、除
/*
键盘输入两个数
选择 + - * / 四个中的一个，对应输出选择运算符计算后的结果
 */
public class Demo05 {
    public static void main(String[] args) {
        double sum = 0;
        double db = 0;
        double db1 = 0;
        double db2 = 0;
        while (true) {
            Scanner scanner = new Scanner(System.in);
            System.out.println("请输入你的第1个数：");
            double num1 = scanner.nextDouble();
            System.out.println("请输入你的第2个数：");
            double num2 = scanner.nextDouble();
            scanner.close();

            System.out.println("请选择你要进行的运算（加、减、乘、除）：");
            Scanner scanner1 = new Scanner(System.in);
            String str = " ";
            str = scanner1.nextLine();
            scanner1.close();
            switch (str){
                case "+":
                    sum = num1 + num2;
                    System.out.println("两个数的和为：" + sum);
                    break;
                case "-":
                    if (num1 > num2) {
                        db = num1 - num2;
                    } else {
                        db = num2 - num1;
                    }
                    System.out.println("两个数的差为：" + db);
                    break;
                case "*":
                    db1 = num1 * num2;
                    System.out.println("两个数的乘积为：" + db1);
                    break;
                case "/":
                    db2 = num1 / num2;
                    System.out.println("两个数相除的结果是：" + db2);
                    break;
                default:
                    System.out.println("你输入的运算符不对，请重新输入！");
            }
        }
    }
}