Problem Statement :
Until Java 7, java.util.Hashmap implementations always suffered with the problem of Hash Collision, i.e. when multiple
hashCode() values end up in the same bucket, values are placed in a Linked List implementation, which reduces Hashmap performance from O(1) to O(n).
Improve the performance of
java.util.HashMap under high hash-collision conditions by using balanced trees rather than linked lists to store map entries.This will improve collision performance for any key type that implements