Java 简单的接口实现

public interface  USB {

public void foo();

}

public class UDisk implements USB {

@Override
public void foo() {
// TODO Auto-generated method stub
System.out.println("U盘正在工作！");
}

}

public class UFan implements USB {

@Override
public void foo() {
// TODO Auto-generated method stub
System.out.println("风扇正在运作！");
}

}

public class Computer {
private USB usb;

public void setUsb(USB usb) {
this.usb = usb;
}
public void UsbWork(){
usb.foo();
}

}

public class Test {
public static void main(String[] args){
Computer computer=new Computer();
USB udisk=new UDisk();
   USB ufan=new UFan();
computer.setUsb(udisk);
computer.UsbWork();
computer.setUsb(ufan);
computer.UsbWork();

}

}