When should I use ConcurrentSkipListMap?

Question

In Java, ConcurrentHashMap is there for better multithreading solution. Then when should I use ConcurrentSkipListMap? Is it a redundan

Answer 1

ConcurrentHashMap : when u want multithreaded index based get/put, only index based operations are supported. Get/Put are of O(1)

ConcurrentSkipListMap : More operations than just get/put, like sorted top/bottom n items by key, get last entry, fetch/traverse whole map sorted by key etc. Complexity is of O(log(n)), So put performance is not as great as ConcurrentHashMap. It't an implementation of ConcurrentNavigableMap with SkipList.

To summarize use ConcurrentSkipListMap when you want to do more operations on map requiring sorted features rather than just simple get and put.