递归

------------恢复内容开始------------

 

 使用循环结构和switch编写计算机

import java.util.Scanner;

public class Demo08 {
    public static void main(String[] args) {
        Demo08 test = new Demo08();
        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);
        Demo08 test = new Demo08();
        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");
            }
        }
    }
}