List problems

[ZeCute]

I am right now reading a Java course. And I have totally get stucked with one of my task.
My task is that I am trying to make a list that i can add and get object from.
I have an API I build my list from, so the methods and the constructor in my classes have to be there. The problem come when I am trying to add some objects to the list. When I am trying to add an object, I only get back null object. And I have no ideé what the problem is. I would be really happy if someone please could told me what I am doing wrong.

import java.lang.Object.*;
public class Node {
    Object item;
    Node next;
    public Node (java.lang.Object newItem) 
    {
        setItem(newItem);
        setNext(null);
    }
    
    public Node(java.lang.Object newItem, Node nextNode)
    {
        setItem(newItem);
        setNext(nextNode);
    }
    
    public void setItem (java.lang.Object newItem)
    {
       item = newItem;
    }
    
    public java.lang.Object getItem()
    {
        return item;
    }
    
    public void setNext(Node nextNode)
    {
        next = nextNode;
    }
    
    public Node getNext()
    {
        return next;
    }
    
}

import java.lang.Object.*;
public class ListReferencedBased implements ListInterface{
    int numItems;
    Node head;
    
    private Node find (int index)
    {
     Node current = head;
     if (index >= numItems)
     {
       return null;
     }
     else
     {
      for (int count=0; count<index; count++)
      {
      current = current.getNext();
      }
      return current;
     }
     }        
    
    public ListReferencedBased()
    {
        head = null;
        numItems = 0;
    }
   
    @Override
    public void add(int index, Object item) throws ListIndexOutOfBoundsException {
        Node pre, cur;
         if (index < 1 || index > numItems+1)
         {
             numItems++;
         }    
            if (isEmpty()) {
            
            head = new Node(item);
            numItems++;
            }
            else{
                head = new Node(find(index), head);
                numItems++;
          }
      
  /*      pre = find(index-1);
        cur = pre.getNext();
        pre.setNext(new Node(item, cur));
    */    
    }

    @Override
    public Object get(int index) throws ListIndexOutOfBoundsException {
       head.setNext(find(index));
       if(find(index) != null)
       {    
       return head.getItem();
       }else{
       return null;
       } 
    }

    @Override
    public boolean isEmpty() {
        if(numItems == 0) 
        {
        return true;
        }
        else
        {    
        return false;    
        }
    }

    @Override
    public void remove(int index) throws ListIndexOutOfBoundsException {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    @Override
    public void removeAll() {
      head.next = null;  
    }
    
     @Override
    public int size() {
  /*    numItems=0;
        while(head!=null)
        {
            numItems++;
            head.getNext();
        }*/
    return numItems;  
    }
}