简易零钱通

package com.hspedu.smallchange.oop;

import com.hspedu.smallchange.SmallChangeSys;

public class SmallChangeSysAPP {
    public static void main(String[] args) {
        new SmallChangeSysOOP().mainMenu();
    }
}

package com.hspedu.smallchange.oop;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;

public class SmallChangeSysOOP {
    boolean loop = true;
    Scanner scanner = new Scanner(System.in);
    String key = "";
    String details = "----------零钱通明细----------";
    double money = 0;
    double balance = 0;
    Date date = null;
    String note = null;
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");
    public void mainMenu() {
        do {
            System.out.println("==========零钱通==========");
            System.out.println("ttt1 零钱通明细");
            System.out.println("ttt2 收益入账");
            System.out.println("ttt3 消费");
            System.out.println("ttt4 退出");
            System.out.println("请选择(1-4):");
            this.key = this.scanner.next();
            switch (this.key) {
                case "1":
                    this.detail();
                    break;
                case "2":
                    this.income();
                    break;
                case "3":
                    this.pay();
                    break;
                case "4":
                    this.exit();
                    break;
                default:
                    System.out.println("选择有误,请重新选择");
            }

        }while(loop);
        System.out.println("-----退出了零钱通项目-----");
    }

    public  void detail(){
        System.out.println(details);
    }
    public  void income(){
        System.out.println("收益入账金额:");
        money=scanner.nextDouble();
        if(money<0){
            System.out.println("收益入账金额不能小于0");
            return;
        }
        balance+=money;
        date =new Date();
        details+="n收益入账t+"+money+"t"+sdf.format(date);
    }

    public  void pay(){
        System.out.println("消费金额:");
        money=scanner.nextDouble();
        if(money<0||money>balance){
            System.out.println("收益入账金额不能小于0");
            return;
        }
        System.out.println("消费说明:");
        note=scanner.next();
        balance-=money;
        date =new Date();
        details+="n"+note+"t-"+money+"t"+sdf.format(date);
    }
    public void exit(){
        String choice="";
        while(true){
            System.out.println("你确定要退出吗？y/n");
            choice=scanner.next();
            if(choice.equals("y")||choice.equals("n")){
                break;
            }
        }
        if(choice.equals("n")){
            return ;
        }
        loop=false;
        return ;
    }
}