25.多态主板实例

需求：
电脑运行实例，电脑运行基于主板。

public class DuoTai_05 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		MainBoard mb=new MainBoard();
		mb.run();
		mb.usePCI(null); 
		mb.usePCI(new NetCard());
		mb.usePCI(new SoundCard());
	}

}
interface PCI{
	public void open();
	public void close();
}
class MainBoard{
	public void run(){
		System.out.println("mainboard run");
	}
	public void usePCI(PCI p){
		if(p !=null){
			p.open();
			p.close();
		}
	}
}
class NetCard implements PCI{
	public void open(){
		System.out.println("netcard open");
	}
	public void close(){
		System.out.println("netcard close");
	}
}
class SoundCard implements PCI{
	public void open(){
		System.out.println("soundcard open");
	}
	public void close(){
		System.out.println("soundcard close");
	}
}