------------------------------- ->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