interface Usb{
public void start();
public abstract void stop();
}
class Computer{
public static void plugin(Usb usb){
usb.start();
usb.stop();
}
}
class Flash implements Usb{
public void start(){
System.out.println("U start");
}
public void stop(){
System.out.println("U stop");
}
}
class Print implements Usb{
public void start(){
System.out.println("print start");
}
public void stop(){
System.out.println("print stop");
}
}
public class Demo025{
public static void main(String[] args){
Computer.plugin(new Flash());
Computer.plugin(new Print());
}
}