How to create an assignFirst method with Nodes in a BinarySearchTree?

Question

I have a binarySearch Tree and I want to create a method assignFirst.

This method should find the node in the tree with the smallest value and update the tree's "first" attribute accordingly.

I have a lot of methods, but I don't want to include all of them in here, since I want to keep it short and simple. Therefore, I will include the class and some features inside that class.

public class BinarySearchTree<E extends Comparable<E>>
{
private BSTNode<E> root; // root of overall tree
private int numElements;
private BSTNode<E> first;
// post: constructs an empty search tree
public BinarySearchTree()
{
    this.root = null;
    this.numElements = 0;
}
private void assignFirst()
{
    if (root.left == null)
    {
        first.data = root.data;
    }
    else
        {
        first.data = root.left.data;
    }
}
public class Iterator
{
    private BSTNode<E> currentNode;

    public Iterator()
    {
        currentNode = first;
    }

    public boolean hasNext()
    {
        return currentNode != null;
    }

    public E next()
    {
        E value = currentNode.data;
        currentNode = currentNode.next;
        return value;
    }
}
private static class BSTNode<E>
{
    public E data;
    public BSTNode<E> left;
    public BSTNode<E> right;
    public BSTNode<E> parent;
    public BSTNode<E> next;

    public BSTNode(E data)
    {
        this(data, null, null, null, null);
    }

    public BSTNode(E data, BSTNode<E> left, BSTNode<E> right, BSTNode<E> parent, BSTNode<E> next)
    {
        this.data = data;
        this.left = left;
        this.right = right;
        this.parent = parent;
        this.next = next;
    }
}
}

I updated my method look like this. I'm still uncertain if this is the correct way of doing it.

private void assignFirst()
{
    if (first.left != null)
    {
        first = first.left;
    }
    else
        {
        first = root;
    }
}

Answer 1

I figured it out. I wrote it in like this.

private void assignFirst()
{
    BSTNode<E> node = root;
    while(node.left != null)
    {
        node = node.left;
    }
    first = node;
}