Difference between List and Set:

List can contain duplicate elements whereas Set contains unique elements only.

HashSet class:

  • uses hashtable to store the elements.It extends AbstractSet class and implements Set interface.
  • contains unique elements only.

Hierarchy of HashSet class:

HashSet class hierarchy

Example of HashSet class:


import java.util.*;
class Simple{
 public static void main(String args[]){
 
  HashSet al=new HashSet();
  al.add("Ravi");
  al.add("Vijay");
  al.add("Ravi");
  al.add("Ajay");

  Iterator itr=al.iterator();
  while(itr.hasNext()){
   System.out.println(itr.next());
  }
 }
}

Output:Ajay
       Vijay
       Ravi