Need help with making an in order iterator using a parent pointer in Java. The class outline is below.

public class BinaryTree { //Implements a Binary Tree of Strings private class Node { private Node left; private String data; private Node right; private Node _parent_; //reference to the parent node // the parent is null for the root node private Node(Node L, String d, Node r, Node p) { left = L; data = d; right = r; parent = p; } } private Node root;

public BinaryTree() { //create an empty tree root = null; }

public BinaryTree(String d) { //create a tree with a single node root = new Node(null,d,null,null); }

public class InorderIterator implements Iterator { //An iterator that returns data in the tree in an in order pattern //the implementation must use the parent pointer and must not use an //additional data structure

public InorderIterator() { } public boolean hasNext() { return true; } public String next() { } }

public Iterator _inorder_() {

//return a new in order iterator object } }