【面向过程编程】零钱通项目

实现效果：

 实现代码：

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


public class SmallChangeSys {
    //main方法
    public static void main(String[] args) {
        SmallChangeSys smallChangeSys = new SmallChangeSys();
        Scanner scanner = new Scanner(System.in);
        boolean flag = true;
        String key = "";
        String details = "---------------零钱通明细---------------";
        double money = 0;
        double balance = 0;//余额
        Date date = new Date();//日期
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd HH:mm");
        String storeName = "";//消费说明
        char answer;
        do {
            //菜单
            System.out.println("n---------------零钱通菜单---------------");
            System.out.println("             1 零钱通明细               ");
            System.out.println("             2 收益入账                 ");
            System.out.println("             3 消费                    ");
            System.out.println("             4 退出                    ");
            System.out.print("请选择(1-4):");
            key = scanner.next();
            switch (key) {
                case "1":
                    System.out.println(details);
                    break;
                case "2":
                    System.out.print("收益入账金额：");
                    money = scanner.nextDouble();
                    
                    if (money <= 0) { //入账金额不能为负数
                        System.out.println("入账金额不能为负数...");
                        break;
                    }
                    balance += money;//入账后的余额
                    date = new Date();//获取当前日期
                    //拼接信息到details
                    details += "n收益入账t" + "+" + money + "t" +
                            sdf.format(date) + "t" + "余额：" + balance;

                    break;
                case "3":
                    System.out.print("消费说明：");
                    storeName = scanner.next();
                    System.out.print("消费金额：");
                    money = scanner.nextDouble();
                    
                    if (money > balance || money <= 0) {//消费金额不能大于余额
                        System.out.println("您的消费金额应该在0-" + balance);
                        break;
                    }
                    balance -= money;//消费后的余额
                    date = new Date();//获取当前日期
                    //拼接信息到details
                    details += "n" + storeName + "t" + "-" + money +
                            "t" + sdf.format(date) + "t" + "余额：" + balance;
                    break;
                case "4":
//                        do {
//                            System.out.println("确认退出？y/n");
//                            answer = scanner.next().charAt(0);
//                            if (answer == 'y') {
//                                flag = false;
//                            }
//                        }while(answer != 'y' && answer != 'n');//输入y/n才能退出循环
                    
                    while (true) {
                        System.out.println("你确定要退出吗？y/n");
                        answer = scanner.next().charAt(0);
                        if (answer == 'y' || answer == 'n') {
                            break;
                        }
                    }
                    if (answer == 'y') {
                        flag = false;
                    }
                    break;
                default:
                    System.out.println("输入有误，重新输入。");
            }
        } while (flag);
        System.out.println("---------退出零钱通---------");
    }
}