Java.util.EnumMap 示例详解编程语言

//populate the map myMealMap.put(MealType.BREAKFAST,"Enjoy Milk and Eggs for breakfast!"); myMealMap.put(MealType.LUNCH,"Enjoy Chicken, Rice and bread for Lunch!"); myMealMap.put(MealType.SNACK,"How about an apple for the evening snack!"); myMealMap.put(MealType.DINNER,"Keep the dinner light, lets have some salad!"); System.out.println("Welcome to meal planner, we have suggestions for following meals : "); //print all the keys of enum map in sorted order System.out.println(myMealMap.keySet()); //We can get the value from enumType System.out.println(" Q: What should I have for lunch? "); System.out.println(" A: "+myMealMap.get(MealType.LUNCH)); System.out.println(" Q: What should I have for snack? "); System.out.println(" A: "+myMealMap.get(MealType.SNACK)); System.out.println(" Q: What should I have for dinner? "); System.out.println(" A: "+myMealMap.get(MealType.DINNER)); //Iterate over enumMap for (MealType mealType : myMealMap.keySet()) { System.out.println(myMealMap.get(mealType)); System.out.println("*** Checking for concurrent modification exception! ***"); //Does not throw Concurrent modification Exception in enumMap for (MealType mealType : myMealMap.keySet()) { if(MealType.SNACK.equals(mealType)){ myMealMap.remove(MealType.SNACK); //map changed without throwing Concurrent modification Exception System.out.println(myMealMap);
Welcome to meal planner, we have suggestions for following meals : [BREAKFAST, LUNCH, SNACK, DINNER] Q: What should I have for lunch? A: Enjoy Chicken, Rice and bread for Lunch! Q: What should I have for snack? A: How about an apple for the evening snack! Q: What should I have for dinner? A: Keep the dinner light, lets have some salad! Enjoy Milk and Eggs for breakfast! Enjoy Chicken, Rice and bread for Lunch! How about an apple for the evening snack! Keep the dinner light, lets have some salad! *** Checking for concurrent modification exception! *** {BREAKFAST=Enjoy Milk and Eggs for breakfast!, LUNCH=Enjoy Chicken, Rice and bread for Lunch!, DINNER=Keep the dinner light, lets have some salad!}

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