[자바] extends, showInfo 문 활용한 예제

 

1. 메인 클래스

public class Main {
    public static void main(String[] args) {
        Yes24 yes24 = new Yes24();
        Books books = new Books();
        yes24.serf(books); // Goods goods=books
        Drone drone = new Drone();
        yes24.serf(drone); // Goods goods=drone
    }
}

 

2. yes24 클래스

class Yes24 {
    void serf(Goods goods) {
        goods.showInfo();
    }
}

 

3. 하위 클래스

class Goods {
        void showInfo() {
        System.out.println("상품");
        }
}
class Books extends Goods {
    void showInfo() {
        System.out.println("책");
    }
}
class Drone extends Goods {
    void showInfo() {
        System.out.println("드론");
    }
}