->HashMap is implementation of Map interface
->Here we can store key value pairs
->When we use put method to set data to hashmap
* Internally get the hashcode of key.
* And based on the hashing algaritham it will find out the bucket location
->the defualt bucket size is 16.
->The same process will happened for get The data from hashmap
** There is chanse of getting same hashcode for multiple objects.
this we called it has collission
in this case intenal of bucket it will create linkedList and assinged.
-->In java 1.8 hashmap performance improved
As we know LinkedList permermance is low for the searching the data.
if mutiple collision occures in the map. in this time hashmap performance also
