下面程序结果为：(     )

class Guy {
    String greet() {
        return "hi";
    }
}
class Cowboy extends Guy {
    String greet() {
        return "howdy";
    }
}
class Surfer extends Guy {
    String greet() {
        return "dude! ";
    }
}
class Greetings {
    public static void main(String[] args) {
        Guy[] guys = {new Guy(), new Cowboy(), new Surfer()};
        for (Guy g : guys)
            System.out.print(g.greet());
    }
}