Difference Between LinkedList and LinkedHashSet in Java

Lets See Difference Between LinkedList and LinkedHashSet in Java

1. Inheritance:
2. How work internally Java LinkedList class uses doubly linked list to store the elements while LinkedHashSet uses LinkedHashMap internally to store it’s elements.
3. uniqueness: LinkedList class can contain duplicate elements while LinkedHashSet contains unique elements only like HashSet.
4. Insertion: LinkedList in case of doubly linked list, we can add or remove elements from both side while LinkedHashSet insert at the end.
5. Constructor: LinkedList have two constructor LinkedList() and LinkedList(Collection o) while LinkedHashSet have four constructor HashSet(), HashSet(Collection c), LinkedHashSet(int capacity) and LinkedHashSet(int capacity, float fillRatio)
6. Insertion, Removal And Retrieval Operations: LinkedList Insertion, Removal And Retrieval Operations performance of order O(n) while LinkedHashSet also gives performance of order O(1) for insertion, removal and retrieval operations.
7. compare the elements: LinkedList use equals() method LinkedHashSet also uses equals() and hashCode() methods to compare the elements.
8. Null Elements: LinkedList allow any number of null values while LinkedHashSet also allows maximum one null element.
9. Syntax: LinkedList syntax is:
   public class LinkedList extends AbstractSequentialList implements List, Deque, Cloneable, Serializable
   
   LinkedHashSet syntax is:
   public class LinkedHashSet extends HashSet implements Set, Cloneable, Serializable

// Java code for Linked List implementation

import java.util.*;

public class Test {
    public static void main(String args[])
    {
        // Creating object of class linked list
        LinkedList<String> object = new LinkedList<String>();

        // Adding elements to the linked list
        // and see carefully element are duplicate, null
        object.add("A");
        object.add("B");
        object.addLast("C");
        object.addFirst("D");
        object.add(2, "E");
        object.add(null);
        object.add(null);
        System.out.println("Linked list : " + object);
        System.out.println("Size of List:" + object.size());
    }
}

Linked list : [D, A, E, B, C, null, null]
Size of List:7

import java.util.LinkedHashSet;
public class Demo {
    public static void main(String[] args)
    {
        LinkedHashSet<String> linkedset = new LinkedHashSet<String>();

        // Adding element to LinkedHashSet
        linkedset.add("A");
        linkedset.add("B");
        linkedset.add("C");
        linkedset.add("D");

        System.out.println("Original LinkedHashSet:" + linkedset);
        System.out.println("Size of LinkedHashSet = " + linkedset.size());

        // trying to add duplicate
        linkedset.add("A");
        System.out.println("After adding duplicate element " + linkedset);
        System.out.println("Size of LinkedHashSet = " + linkedset.size());

        // trying to add null value more than one
        linkedset.add(null);
        linkedset.add(null);
        System.out.println("After adding two null element " + linkedset);
        System.out.println("Size of LinkedHashSet = " + linkedset.size());
    }
}

Original LinkedHashSet:[A, B, C, D]
Size of LinkedHashSet = 4
After adding duplicate element [A, B, C, D]
Size of LinkedHashSet = 4
After adding two null element [A, B, C, D, null]
Size of LinkedHashSet = 5