Java LinkedHashMap

In this tutorial, we will learn about the Java LinkedHashMap class and its operations with the help of examples.

The LinkedHashMap class of the Java collections framework provides the hash table and linked list implementation of the Map interface.

LinkedHashMap is just like HashMap with an additional feature of maintaining an order of elements inserted into it. HashMap provided the advantage of quick insertion, search and deletion but it never maintained the track and order of insertion which the LinkedHashMap provides where the elements can be accessed in their insertion order. Let’s see how to create a map object using this class.

Example:

// Java Program to illustrate the LinkedHashmap Class 
import java.util.*; 

public class Codemistic { 

	public static void main(String[] args) 
	{ 
		Map<String, Integer> map 
			= new LinkedHashMap<>(); 

		map.put("ayush", 10); 
		map.put("anvi", 30); 
		map.put("pragya", 20); 

		for (Map.Entry<String, Integer> e : map.entrySet()) 
			System.out.println(e.getKey() + " "
							+ e.getValue()); 
	} 
} 
output:
ayush 20
anvi 10
pragya 30

Important Features of a LinkedHashMap:

• A LinkedHashMap contains values based on the key. It implements the Map interface and extends HashMap class.
• It contains only unique elements.
• It may have one null key and multiple null values.
• It is same as HashMap with an additional feature that it maintains insertion order. For example, when we run the code with a HashMap, we get a different order of elements.

Methods in Java LinkedHashMap