LinkedHashSet Class in Java with Example

Earlier we have shared tutorials on HashSet and TreeSet. LinkedHashSet is also an implementation of Set interface, it is similar to the HashSet and TreeSet except the below mentioned differences:

1. HashSet doesn’t maintain any kind of order of its elements.
2. TreeSet sorts the elements in ascending order.
3. LinkedHashSet maintains the insertion order. Elements gets sorted in the same sequence in which they have been added to the Set.

Example of LinkedHashSet:

import java.util.LinkedHashSet;
public class LinkedHashSetExample {
     public static void main(String args[]) {
         // LinkedHashSet of String Type
         LinkedHashSet<String> lhset = new LinkedHashSet<String>();

         // Adding elements to the LinkedHashSet
         lhset.add("Z");
         lhset.add("PQ");
         lhset.add("N");
         lhset.add("O");
         lhset.add("KK");
         lhset.add("FGH");
         System.out.println(lhset);

         // LinkedHashSet of Integer Type
         LinkedHashSet<Integer> lhset2 = new LinkedHashSet<Integer>();

         // Adding elements
         lhset2.add(99);
         lhset2.add(7);
         lhset2.add(0);
         lhset2.add(67);
         lhset2.add(89);
         lhset2.add(66);
         System.out.println(lhset2);
    }
}

Output:

[Z, PQ, N, O, KK, FGH]
[99, 7, 0, 67, 89, 66]

Observe the output: Both types of LinkedHashSet have preserved the insertion order.