HashMap vs ConcurrentHashMap
ConcurrentHashMap was introduce with JDK1.5 release to replace legacy class Hashtable. In multithreaded environment ConcurrentHashMap performs better as compared to Hashtable and Synchronized Map as well. All methods of Hashtable are synchronized which makes them quite slow due to contention if a number of thread increases. While ConcurrentHashMap is specially designed for concurrent uses which by default allows 16 threads to simultaneously read and write from map without any external synchronization. …