照着老师的例子打的，可为什么报错啊。。求大神解答

public class Smartphone extends Telphome implements Iplaygame {

@Override

public void call() {

// TODO Auto-generated method stub

System.out.println("通过语音来打电话");

}

@Override

public void message() {

// TODO Auto-generated method stub

System.out.println("通过语音来发短信");

}

@Override

public void playgame() {

// TODO Auto-generated method stub

System.out.println("具有玩游戏的功能");

}

}

public interface Iplaygame {

public void playgame();

}

public class PSP implements Iplaygame {

public void playgame() {              //系统这里报错，不知道为什么，求大神解答

// TODO Auto-generated method stub

}

}