LinkedHashMap VS HashMap Difference In Java [ Updated 2023 ]

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HashMap vs LinkedHashMap In Java: In this article, we will discuss the difference between HashMap and LinkedHashMap classes in detail i.e.; HashMap vs LinkedHashMap

Lets us move on and discuss the key differences between these 2 Map implemented classes

HashMap vs LinkedHashMap

HashMap	LinkedHashMap
Uses a hash table to store map entries (i.e.; key-value pairs)	Uses a combination of hash table + LinkedList to store map entries (i.e.; key-value pairs)
Doesn’t maintain insertion order i.e.; while iterating through HashMap, we will get map entries in random order	Since it uses the doubly-linked list to store map entries (i.e.; key-value pairs), maintains insertion order
This is introduced in the original collection framework in Java 1.2 version	This is introduced in Java 1.4 version

When to use HashMap?

HashMap stores key-value pairs which use a hashing technique to store key-value pairs
So, the search operation is faster
So, if the business requirement is to store key-value pairs for faster search operation or number of search operation on the basis of keys; without concerning insertion order
Then, HashMap is the very apt choice

When to use LinkedHashMap?

This is exactly the same as that of HashMap, but underlying data structure to hold key-value pairs is different
It uses a doubly-linked list which allows holding key-value pairs as per insertion order
So, if a business requirement is to store key-value pairs for faster search operation or number of search operation concerning/maintaining insertion order
Then, LinkedHashSet is the very apt choice which maintains insertion order
So while iterating through LinkedHashSet, we will get map entry (key-value pairs) as per insertion order (as against random in HashMap)

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