如何使用番石榴的MultiMap拆分值列表

Question

Map is of type Map<String, List<MyClass>> I have more than 100 objects of MyClass associated with Key. I need to split it if it's more than 100.

For eg Input is

Map<String, List<MyClass>> myMap = new HashMap<String, List<MyClass>>();

myMap.put("ABC", [CustomObject1,CustomObject2,CustomObject3....CustomObject100...CustomObject110]);

& Output should be

myMap.put("ABC", [CustomObject1,CustomObject2,CustomObject3....CustomObject100]);
myMap.put("ABC", [CustomObject100,CustomObject101....CustomObject110]);

I thought of getting myMap.containsKey(string) and check size of list and then create new entry or add it in same. I tried using guava's multimap but it returns Collection> when I try to get elements so not sure how to insert it. Or if there is any better option for this?

Answer 1

Try using Guava Lists.partition

Map<String, List<MyClass>> myMap = new HashMap<String, List<MyClass>>();

myMap.put("ABC", [CustomObject1,CustomObject2,CustomObject3....CustomObject100...CustomObject110]);

Map<String, List<List<MyClass>>> output = myMap.entrySet().stream().collect(Collectors.toMap(e -> e.getKey(), e -> Lists.partition(e.getValue(), 100)));