NullPointerException error in AVL tree
<p>I am doing an assignment about AVL trees in Java. I am getting a <code>NullPointerException</code> error when trying to balance the tree by means of the rotation. Can you please help me in finding the error? Here is my code:</p>

<pre><code>public class Node {
    private int value;
    private Node leftNode;
    private Node rightNode;

    public Node(int value) {
        this.value = value;
    }
</code></pre>
