Java 多态的主板示例

/*
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());
}
}