练习——简易计算

package com.q1u.method;

import java.util.Scanner;

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

        //判断是否有数的输入
        while (true){
            System.out.println("请输入第一个数");
            if (scanner.hasNextDouble()){
                double i = scanner.nextDouble();
                System.out.println("请输入第二个数");
                if (scanner.hasNextDouble()){
                    double j = scanner.nextDouble();
                    System.out.println("请输入运算符");
                    if (scanner.hasNext()){
                        String str = scanner.next();
                        switch(str){
                            case "*":
                                System.out.println("运算结果为： "+mul(i,j));
                                break;
                            case "/":
                                System.out.println("运算结果为： "+div(i,j));
                                break;
                            case "+":
                                System.out.println("运算结果为： "+add(i,j));
                                break;
                            case "-":
                                System.out.println("运算结果为： "+sub(i,j));
                                break;
                            default:
                                System.out.println("输入的运算符有误，请重头开始重新运算！");
                        }
                    }
                }else {
                    System.out.println("输入的不是数,程序结束！");
                    break;
                }
            }else {
                System.out.println("输入的不是数，程序结束！");
                break;
            }

        }
        scanner.close();
    }

    //加方法
    public static double add(double num1,double num2){
        return num1+num2;
    }
    //减方法
    public static double sub(double num1,double num2){
        return num1-num2;
    }//乘方法
    public static double mul(double num1,double num2){
        return num1*num2;
    }//除方法
    public static double div(double num1,double num2){
        return num1/num2;
    }
}