Set vs HashSet vs TreeSet in Java

A Set is a generic set of values with no duplicate elements. A TreeSet is a set where the elements are sorted.

A HashSet is a set where the elements are not sorted or ordered. It is faster than a TreeSet. The HashSet is an implementation of a Set.

Set is a parent interface of all set classes like TreeSet, HashSet, etc.

Example

 Live Demo

import java.util.*; public class Demo {    public static void main(String args[]) {       int a[] = {77, 23, 4, 66, 99, 112, 45, 56, 39, 89};       Set<Integer> s = new HashSet<Integer>();       try {          for(int i = 0; i < 5; i++) {             s.add(a[i]);          }       System.out.println(s);       TreeSet sorted = new TreeSet<Integer>(s);       System.out.println("Sorted list = ");       System.out.println(sorted);       } catch(Exception e) {}    } }

Output

[66, 99, 4, 23, 77] Sorted list = [4, 23, 66, 77, 99]