How to create our own HashSet Implementation in Java ?

1)CustomHashSet.java

   package customhashset;

   import java.util.Iterator;
   import java.util.NoSuchElementException;
 
   /**
      This class implements a hash set using separate chaining.
   */
   public class CustomHashSet
   {
     private Node[] buckets;
     private int currentSize;

     /**
        Constructs a hash table.
        @param bucketsLength the length of the buckets array
     */
     public CustomHashSet(int bucketsLength)
     {
        buckets = new Node[bucketsLength];
        currentSize = 0;
     }

     /**
        Tests for set membership.
        @param x an object
        @return true if x is an element of this set
     */
     public boolean contains(Object x)
     {
        int h = x.hashCode();
        if (h < 0) { h = -h; }
        h = h % buckets.length;

        Node current = buckets[h];
        while (current != null)
      {
           if (current.data.equals(x)) { return true; }
           current = current.next;
        }
        return false;
     }

     /**
        Adds an element to this set.
        @param x an object
        @return true if x is a new object, false if x was
        already in the set
     */
     public boolean add(Object x)
     {
        int h = x.hashCode();
        if (h < 0) { h = -h; }
        h = h % buckets.length;

        Node current = buckets[h];
        while (current != null)
        {
           if (current.data.equals(x)) { return false; }
              // Already in the set
           current = current.next;
        }
        Node newNode = new Node();
        newNode.data = x;
        newNode.next = buckets[h];
        buckets[h] = newNode;
        currentSize++;
        return true;
     }

     /**
        Removes an object from this set.
        @param x an object
        @return true if x was removed from this set, false
        if x was not an element of this set
     */
     public boolean remove(Object x)
     {
        int h = x.hashCode();
        if (h < 0) { h = -h; }
        h = h % buckets.length;

        Node current = buckets[h];
        Node previous = null;
        while (current != null)
        {
           if (current.data.equals(x))
           {
              if (previous == null) { buckets[h] = current.next; }
              else { previous.next = current.next; }
              currentSize--;
              return true;
           }
           previous = current;
           current = current.next;
        }
        return false;
     }

     /**
        Returns an iterator that traverses the elements of this set.
       @return a hash set iterator
    */
    public Iterator iterator()
    {
       return new HashSetIterator();
    }

    /**
       Gets the number of elements in this set.
       @return the number of elements
    */
    public int size()
    {
       return currentSize;
    }

    class Node
    {
       public Object data;
       public Node next;
    }

    class HashSetIterator implements Iterator
    {
       private int bucketIndex;
       private Node current;

       /**
          Constructs a hash set iterator that points to the
          first element of the hash set.
       */
       public HashSetIterator()
       {
          current = null;
          bucketIndex = -1;
       }

       public boolean hasNext()
       {
          if (current != null && current.next != null) { return true; }
          for (int b = bucketIndex + 1; b < buckets.length; b++)
          {
             if (buckets[b] != null) { return true; }
          }
          return false;
       }

       public Object next()
       {
          if (current != null && current.next != null)
          {
             current = current.next; // Move to next element in bucket
          }
          else // Move to next bucket
          {
             do
             {
                bucketIndex++;
                if (bucketIndex == buckets.length)
                {
                   throw new NoSuchElementException();
                }
                current = buckets[bucketIndex];
             }
             while (current == null);
          }
          return current.data;
       }

       public void remove()
       {
          throw new UnsupportedOperationException();
       }
    }
 }


2)HashSetDemo.java

package customhashset;
import java.util.Iterator;

  /**
     This program demonstrates the hash set class.
  */
  public class HashSetDemo
  {
     public static void main(String[] args)
      {
       CustomHashSet names = new CustomHashSet(101);

       names.add("Harry");
       names.add("Sue");
       names.add("Nina");
       names.add("Susannah");
       names.add("Larry");
       names.add("Eve");
       names.add("Sarah");
       names.add("Adam");
       names.add("Tony");
       names.add("Katherine");
       names.add("Juliet");
       names.add("Romeo");
       names.remove("Romeo");
       names.remove("George");

       Iterator iter = names.iterator();
       while (iter.hasNext())
       {
          System.out.println(iter.next());
       }
    }
 }