Java通过循环结构和switch实现简易计算器

Java通过循环结构和switch实现简易计算器

可以循环计算，通过调用函数本身来实现重新计算

package com.shenxiaoyu.method;

import java.util.Scanner;

public class TestDemo {
    public static void main(String[] args) {
        TestDemo test= new TestDemo();
        test.computer();
    }
    //加
    public double add(double num1){
        Scanner input3 = new Scanner(System.in);
        System.out.println("输入一个数：");
        double num2 = input3.nextDouble();

        return (num1+num2);
    }
    //减
    public double subtract(double num1){

        Scanner input3 = new Scanner(System.in);
        System.out.println("输入一个数：");
        double num2 = input3.nextDouble();

        return (num1-num2);
    }
    //乘
    public double multiply(double num1){

        Scanner input3 = new Scanner(System.in);
        System.out.println("输入一个数：");
        double num2 = input3.nextDouble();

        return (num1*num2);
    }
    //除
    public double divide(double num1){
        Scanner input3 = new Scanner(System.in);
        System.out.println("输入一个数：");
        double num2 = input3.nextDouble();

        return (num1/num2);
    }
   //实现计算器循环计算
    public void computer(){
        Scanner input1 = new Scanner(System.in);
        TestDemo test= new TestDemo();
        System.out.println("输入一个数：");
        double a = input1.nextDouble();
        while(true){
            Scanner input2 = new Scanner(System.in);
            System.out.println("请输入您的操作:(加(+)减(-)乘(-)除(/)E(重新计算)退出(Q))：");
            String str = input2.nextLine();
            char chr = str.toCharArray()[0];
            switch(chr){
                case '+':
                    a = test.add(a);
                    System.out.println("和："+a);
                    break;
                case '-':
                    a = test.subtract(a);
                    System.out.println("减："+a);
                    break;
                case '*':
                    a = test.multiply(a);
                    System.out.println("乘："+a);
                    break;
                case '/':
                    a = test.divide(a);
                    System.out.println("除："+a);
                    break;
                case 'Q':
                    System.exit(-1);
                case 'E':
                    computer();
                default:
                    System.out.println("输入有误");
            }
        }
    }
}