Difference Between HashMap and ConcurrentHashMap in Java

1. Introduction Both HashMap and ConcurrentHashMap are used to store key-value pairs, but they differ mainly in: Thread safety Performance in multi-threaded environments Internal working mechanism 2. HashMap Explanation HashMap is not thread-safe. Multiple threads accessing it simultaneously may lead to: Data inconsistency Infinite loops (in older Java versions during resizing) It is best suited for single-threaded environments. Examp