Hash collisions in Java's ConcurrentHashMap: which precautions must be taken? [duplicate]
Solution 1:
Javas ConcurrentHashMap uses a HashTable as the underlying data structure to store entries. The way this table deals with collisions is described here: How do HashTables deal with collisions?
Generally you don't need to be concerned about hash collision when using the HashMap and ConcurrentHashMap types of the standard library. Those are guaranteed to not cause problems with keys that have the same hash values.