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

Then when should I use ConcurrentSkipListMap?

When you (a) need to keep keys sorted, and/or (b) need the first/last, head/tail, and submap features of a navigable map.

The ConcurrentHashMap class implements the ConcurrentMap interface, as does ConcurrentSkipListMap. But if you also want the behaviors of SortedMap and NavigableMap, use ConcurrentSkipListMap

ConcurrentHashMap

• ❌ Sorted
• ❌ Navigable
• ✅ Concurrent

ConcurrentSkipListMap

• ✅ Sorted
• ✅ Navigable
• ✅ Concurrent

Here is table guiding you through the major features of the various Map implementations bundled with Java 11. Click/tap to zoom.

Keep in mind that you can obtain other Map implementations, and similar such data structures, from other sources such as Google Guava.