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 saveData()

　　readData(): use DataInputStream get data　“CarData.txt”, and then put data into class car’s object.

saveData(): use Array store cars’ data　their object, and use DataOutputStream to store data in “CarData.txt”



Class AddAndDel:

　　Includes 2 methods, addNewCar() and DelSoldCar()

　　addNewCar(): read Child object of car, add a new object in the end. Scan its details.

　　DelSoldCar(): scan the number of the sold car, mark it and scan its sale price and date of sale.



Class Show:

　　Includes 4 methods, showAll(), showOnList(), showOnListByDate() and showSold()

　　showAll(): Traversing all child objects and print them on screen.

　　showOnList():Traversing all child objects, recognize which have not been sold and print them on screen.

　　showOnListByDate(): On basis of showOnList(), using Bubbling algorithm to sort dates