我們以去KFC訂餐為例

步驟1

這是KFC所賣的食物

public class Food {
    private String Zhaji;//炸雞
    private String Kele;//可樂
    private String Hanbao;//漢堡
    public String getZhaji() {
        return Zhaji;
    }
    public void setZhaji(String zhaji) {
        Zhaji = zhaji;
    }
    public String getKele() {
        return Kele;
    }
    public void setKele(String kele) {
        Kele = kele;
    }
    public String getHanbao() {
        return Hanbao;
    }
    public void setHanbao(String hanbao) {
        Hanbao = hanbao;
    }
}

步驟2

KFC店

public abstract class KFC {
    Food food = new Food();
    
    void makeZhaji() {};
    void makeKele() {};
    void makeHanbao() {};
    
    Food getFood() {
        return food;
    };
}

步驟3

KFC賣的A套餐

public class KFC_A extends KFC{
    @Override
    void makeZhaji() {
        // TODO Auto-generated method stub
        super.makeZhaji();
        food.setZhaji("炸全雞");
    }
    @Override
    void makeKele() {
        // TODO Auto-generated method stub
        super.makeKele();
        food.setKele("小杯可樂");
    }
    @Override
    void makeHanbao() {
        // TODO Auto-generated method stub
        super.makeHanbao();
        food.setHanbao("雞腿堡");
    }
}

B套餐

public class KFC_B extends KFC{
    @Override
    void makeKele() {
        // TODO Auto-generated method stub
        super.makeKele();
        food.setKele("中杯可樂");
    }
    @Override
    void makeHanbao() {
        // TODO Auto-generated method stub
        super.makeHanbao();
        food.setHanbao("鱈魚堡");
    }
}

步驟4

/**
 * 菜單
 * @author USER
 *
 */
public class KFCMenu {
    /**
     * A套餐
     * @param a
     * @return
     */
    public Food getA(KFC_A a) {
        a.makeHanbao();
        a.makeKele();
        a.makeZhaji();
        return a.getFood();
    }
    /**
     * B套餐
     * @param b
     * @return
     */
    public Food getB(KFC_B b) {
        b.makeHanbao();
        b.makeKele();
        return b.getFood();
    }
}

步驟5

測試

KFCMenu menu = new KFCMenu();
//套餐A
Food food_a = menu.getA(new KFC_A());
System.out.println(food_a.getHanbao());
System.out.println(food_a.getKele());
System.out.println(food_a.getZhaji());

System.out.println("==================");

//套餐B
Food food_b = menu.getB(new KFC_B());
System.out.println(food_b.getHanbao());
System.out.println(food_b.getKele());