interface Player{
void play();
}
class ApplePhone implements Player{
void play(){
}
}
class WalkMan implements Player{
void play(){
}
}
public class Main{
public static void main(String[] args){
ApplePhone phone=new ApplePhone();
WalkMan walkman=new WalkMan();
play(phone);
play(walkman);
}
public static void play(Player player){
player.play();
}
}