猜数字，系统给你东西，你猜，知道你才到为止。-Guessing, the system gives you something, you guessed it, knowing you only to the date.

主要详细的介绍了在android 获取系统当前时间 -Mainly introduced to get the current system time in android

统计Linux系统中文件属性,权限，修改或创建日期，最后做一个汇总。-Statistics Linux system file attributes, permissions, modification or creation date, last a summary.

简易二手车管理系统 可添加删除车辆、修改车辆具体信息（车型、厂家、型号、购入时间、购入价格、是否售出、售出价格）、将车辆信息保存到外部文档、从外部文档读取车辆信息-System Design Class car: includes car’s self-attributes, such as its number, logo, price.etc. Class DataStream: includes 2 methods, readData() and saveDa