HashSet : add : Add an element to the Set

public boolean add(E e)

Adds the specified element to this set if it is not already present. Return true if this set did not already contain the specified element.

import java.util.*;

class HashSetAdd{
 public static void main(String args[]){
  HashSet<Integer> mySet = new HashSet<> ();
  
  /* Add Elements to HashSet */
  mySet.add(10);
  mySet.add(20);
  mySet.add(30);
  mySet.add(40);
  
  System.out.println("Elements in HashSet are");
  System.out.println(mySet);
  
  System.out.print("\nIs 50 added to set ");
  System.out.println(mySet.add(50));
  
  System.out.println("\nElements in HashSet are");
  System.out.println(mySet);
  
  System.out.print("\nIs 10 added to set ");
  System.out.println(mySet.add(10));
  
  System.out.println("\nElements in HashSet are");
  System.out.println(mySet);
 } 
}

Output

Elements in HashSet are
[20, 40, 10, 30]

Is 50 added to set true

Elements in HashSet are
[50, 20, 40, 10, 30]

Is 10 added to set false

Elements in HashSet are
[50, 20, 40, 10, 30]

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