151220DuoTaiDemo4

package java151220;

/*

需求:电脑运行实例;

电脑运行基于主板

*/

//扩展接口

interface PCI{

public abstract void open();

public abstract void close();

}

class MainBoard{

public void run() {

System.out.println("MainBoard run !");

}

public void usePCI(PCI pci) {//PCI pci=new NetCard();//接口型引用指向自己的子类对象

if (pci != null) {

pci.open();

pci.close();

}

// pci.open();

// pci.close();

}

}

class NetCard implements PCI{

@Override

public void open() {

System.out.println("netcard open !");

}

@Override

public void close() {

System.out.println("netcard close !");

}

}

class SoundCard implements PCI{

@Override

public void open() {

}

@Override

public void close() {

}

}

public class DuoTaiDemo4 {

public static void main(String[] args) {

MainBoard mainBoard=new MainBoard();

mainBoard.run();

mainBoard.usePCI(null);

mainBoard.usePCI(new NetCard());

mainBoard.usePCI(new SoundCard());

}

}

/*

public class DuoTaiDemo4 {

public static void main(String[] args) {

MainBoard mainBoard=new MainBoard();

mainBoard.run();

mainBoard.useNetCard(new NetCard());

}

}

class NetCard{

public void open() {

System.out.println("netcard open !");

}

public void close() {

System.out.println("netcard close !");

}

}

class MainBoard{

public void run() {

System.out.println("MainBoard run !");

}

public void useNetCard(NetCard netCard) {

netCard.open();

netCard.close();

}

}

*/