HashMap is a class that implements the Map interface using a hash table. Two implementations of Map in Java Standard Edition are HashMap and LikedHashMap. The HashMap extends AbstractMap class and implements Map interface, whereas the LinkedHashMap extends HashMap class and implements Map interface. HashMap has complexity of O(1) for insertion and lookup. The getKey method displays the keys while the getValues method prints the values corresponding to those keys. LinkedHashMap uses HashTable along with Linked List to store map. If you iterate through the keys, though, the ordering of the keys is essentially arbitrary. Similarity between HashMap vs Hashtable vs LinkedHashMap vs TreeMap > Property. HashMap does not maintain any order. “HashMap in Java – Javatpoint.” Www.javatpoint.com, Available here.2. java.util. The main difference between HashMap and LinkedHashMap is that HashMap does not maintain the order of data insertion while LinkedHashMap maintains the order of data insertion. LinkedHashMap class maintains the entries in the map based on their insertion order. Two implementations of Map in Java Standard Edition are HashMap and LikedHashMap. HashMap is implemented as a hash table. It extends the HashMap class which is another very commonly used implementation of the Map interface -. This article discussed the difference between HashMap and TreeMap which implements the Map interface. A HashMap is implemented as Hash table, a TreeMap is implemented as Red-Black Tree, and LinkedHashMap is implemented as doubly-linked list of Buckets in Java. In programming, there are various mechanisms to collect data. All four (HashMap, LinkedHashMap, TreeMap, HashTable) in Java, implements the Map interface. It extends the HashMap class which is another very commonly used implementation of the Map interface -. In this article, we're going to compare two Map implementations: TreeMap and HashMap. 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