Java 多态的主板示例

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/*需求：电脑运行实例，电脑运行基于主板。*/interface PCI //扩展槽{public void open();public void close();}class MainBoard //主板{public void run(){System.out.println("mainboard run ");}public void usePCI(PCI p)//PCI p = new NetCard()//接口型引用指向自己的子类对象{if(p!=null){p.open();p.close();}}}//接口的出现增加了功能的扩展，多态的应用提高了程序的扩展性class NetCard implements PCI{public void open(){System.out.println("netcard open");}public void close(){System.out.println("netcard close");method();}}class SoundCard implements PCI{public void open(){System.out.println("SoundCard open");}public void close(){System.out.println("SoundCard close");}}/*class MainBoard{public void run(){System.out.println("mainboard run");}public void useNetCard(NetCard c){c.open();c.close();}}class NetCard{public void open(){System.out.println("netcard open");}public void close(){System.out.println("netcard close");}}*/class DuoTaiDemo5 {public static void main(String[] args) {MainBoard mb = new MainBoard();mb.run();mb.usePCI(null);mb.usePCI(new NetCard());mb.usePCI(new SoundCard());}}

——摘自《毕向东25天》

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