枚举嵌套

package com.example.testenum;

import java.util.Random;

/**
 * Created by admin on 2018/6/5.
 * 通过这种方式很方便组织上述情景，同时确保每种具体类型的食物也属于Food
 * ,现在我们利用一个枚举嵌套枚举的方式把前面定义的菜谱放到一个Meal菜单中，
 * 通过这种方式就可以同意管理菜单的数据了。
 */
public enum MealEnum {
    APPETIZER(Food.Appetizer.class),
    MAINCOURSE(Food.MainCourse.class),
    DESSERT(Food.Dessert.class),
    COFFEE(Food.Coffee.class);

    private Food[] values;

    MealEnum(Class<? extends Food> kind){
        //通过class对象获取枚举实例
        values = kind.getEnumConstants();
        System.out.println("values:"+values.getClass().getSimpleName());
    }

    interface Food {
        enum Appetizer implements Food {
            SALAD, SOUP, SPRING_ROLLS;
        }
        enum MainCourse implements Food {
            LASAGNE, BURRITO, PAD_THAI,
            LENTILS, HUMMOUS, VINDALOO;
        }
        enum Dessert implements Food {
            TIRAMISU, GELATO, BLACK_FOREST_CAKE,
            FRUIT, CREME_CARAMEL;
        }
        enum Coffee implements Food {
            BLACK_COFFEE, DECAF_COFFEE, ESPRESSO,
            LATTE, CAPPUCCINO, TEA, HERB_TEA;
        }
    }


    public Food randomSelection() {
        return Enums.random(values);
    }



    public static void main(String[] args) {

        for (int i = 0; i < 5; i++) {
            for (MealEnum meal : MealEnum.values()) {
                Food food = meal.randomSelection();
                System.out.println(food);
            }
            System.out.println("---");

        }
    }
}

/**
 * Created by admin on 2018/6/5.
 */
public class Enums {

    private static Random rand = new Random(47);
    public static <T> T random(T[] values){
        return values[rand.nextInt(values.length)];
    }
}