我现在用EVE游戏中飞船的关系来对abstract、virtual、override这3个关键字举例。
先看下类关系图:
Spacecraft为所有飞船的基类。
Caldari(加达里)、Amarr(艾玛)是两个种族(不同的种族之间,武器和防御种类方法不一样,属性加成也不一样)。
Drake、Hawk是Caldari族的两艘飞船;Vengeance是Amarr族的飞船。
业务描述:
首先飞船基类拥有一个所有飞船速度的基数,不同种族的飞船对于速度的基数有各自的加成。
每个种族的武器系统、防御系统均不相同。但实施的效果相同,都是攻击、防御。
对于某个种族的飞船,均拥有自己的名字,在种族速度修正基础上,继续累加自己的速度倍数。更细化属于自己种族的武器分类。
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分析:
所有飞船基类:拥有2个字段(名字、基础速度常量),2个虚访问器(获得名字、速度),2个抽象方法(武器系统、防御系统),展示飞船(重写toString()方法)。
Caldari族(抽象类):继承基类,重写了获得名字和速度的访问器(在名字前面加上种族名称,在基础速度上提高1.4倍作为种族特性。) 实现了武器系统方法(导弹类),并再定义1个导弹抽象方法,定义飞船速度校准虚方法(默认返回1倍)。
Hawk:继承Caldari族,定义构造方法为_name赋值,实现导弹的抽象方法,定义具体导弹名称,重写速度校准倍数为:在种族基础上的5倍。
运行结果: