Implementing an AddAtIndex method in a LinkedList

currently, I am working on implementing an AddAtIndex method and for the most part it seems to be working fine. However, my method is not passing my JUnit test and I can't seem to understand why. Thus, I have chosen to show the code I have done thus far:

**

     * Add an element to the list at the specified index

     * @param The index where the element should be added

     * @param element The element to add

     */

    public void add(int index, E element ) //Method should be O(1) time.

    {

        // TODO: Implement this method

        if (index < 0) { 

            System.out.println("Can't add an element at a negative index.");

        }

        int i = 0;

        LLNode<E> currentNode = head.next;

        while ( i < size ) {

            if ( i == index ) {

                LLNode<E> newNode = new LLNode<E>(element);

                LLNode<E> tempNode = new LLNode<E>(currentNode.data);



                currentNode.next = tempNode;

                currentNode.data = newNode.data;



                newNode.prev = currentNode.prev;

                newNode.next = tempNode;

                tempNode.prev = newNode;

                size++;

            }

            currentNode = currentNode.next;

            i++;

        }



    }

My thought process behind the code is that the method creates a new Node, then it replaces the data at the specified index of the linked list. However, the data at the node it is replacing is stored in a temporary node which is incremented in position to the next node after the new node. I am about 80% confident in my implementation though the code looks a bit sloppy. I have created a driver to demonstrate the implementation. The drivers code is as follows:

public class LinkedListDriver {



    public static void main(String[] args) {

        // TODO Auto-generated method stub

        MyLinkedList<String> nameList = new MyLinkedList<String>();

        nameList.add("Hamadi");

        nameList.add("Ballo");

        nameList.add(1, "Salisu");

        nameList.add(2, "Galo");

        System.out.println(nameList.toString());

        System.out.println(nameList.size());

        nameList.set(2, "Abdullahi");

        System.out.println(nameList.toString());

        nameList.remove(1);

        System.out.println(nameList.toString());

        MyLinkedList<Integer> list1 = new MyLinkedList<Integer>();

        list1.add(65);

        list1.add(21);

        list1.add(42);

        System.out.println(list1.toString());

        list1.remove(0);

        System.out.println(list1.toString());

    }



}

The Output from the driver is as follows:

List: Hamadi, Salisu, Galo, Ballo, 

4

Replacing Galo with Abdullahi

List: Hamadi, Salisu, Abdullahi, Ballo, 

Removing Salisu from the list

List: Hamadi, Abdullahi, Ballo, 

List: 65, 21, 42, 

Removing 65 from the list

List: 21, 42, 

The unit test fails however with the following error:

It fails at the AssertEquals method:

shortList.add(2, "E");

        shortList.add(3, "F");

        **assertEquals("AddAtIndex: at position 2 ", "E", shortList.get(2)); //fails here**

        assertEquals("AddAtIndex: at position 3 ", "F", shortList.get(3));

        assertEquals("AddAtIndex: List size is ", 6, shortList.size());

I would like to know what I'm doing wrong. I have this literally completely figured out, though I know that there is something a bit off about my AddAtindex method. Thanks!