Simple Java HashSet example

      public class SimpleHashSetExample
   {
     public static void main(String[] args)
     {
       //create object of HashSet
       HashSet hSet = new HashSet();
      
       /*
       Add an Object to HashSet using
       boolean add(Object obj) method of Java HashSet class.
       This method adds an element to HashSet if it is not already present in HashSet.
       It returns true if the element was added to HashSet, false otherwise.
       */
      
       hSet.add(new Integer("1"));
       hSet.add(new Integer("2"));
       hSet.add(new Integer("3"));
      
       /*
       Please note that add method accepts Objects. Java Primitive values CAN NOT
       be added directly to HashSet. It must be converted to corrosponding
       wrapper class first.
       */
      
       System.out.println("HashSet contains.." + hSet);
     }
   }