Hashmap in java: Hash table based implementation of the Map

Hash table based implementation of the Map interface. This implementation provides all of the optional map operations, and permits null values and the null key. (The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized and permits nulls.) This class makes no guarantees as to the order of the map; in particular, it does not guarantee that the order will remain constant over time. This implementation provides constant-time performance for the basic operations (get ... The HashMap class uses a hashtable to implement the Map interface. This allows the execution time of basic operations, such as get ( ) and put ( ), to remain constant even for large sets. A HashMap is a part of Java ’s Collection Framework and implements the Map interface. It stores elements in key-value pairs, where, Keys are unique. and Values can be duplicated. Internally uses Hashing, hence allows efficient key-based retrieval, insertion, and removal with an average of O (1) time. In this article, we will understand the internal workings of the HashMap in Java , also how the get () and put () method functions, how hashing is done, how key-value pairs are stored and how the values are retrieved by keys. Basic Structure of a HashMap HashMap contains an array of Node objects. Each node represents a key-value mapping. This process is defined below: class Node { int hash; K key; V value; Node next; } Each node stores, hash: the hash code of the key key: the key object value ...