I had so much trouble implementing an iterator who traverses my tree using in-order traversal in an iterative way.

Here below the solution who came up thanks to Ivano and Fabio.

Hope it can helps.

The complete code of BinaryTree is available here (use at your own risk)



 private class BinTreeIterator implements Iterator{
  

        private Node p;
        private boolean complete;

        public BinTreeIterator(Node root) {
                p = root;
                complete = false;
                setNotVisitedNode(root);

                // set p to the smallest element of the tree
                while (p.getLeftChild() != null)
                        p = p.getLeftChild();
        }

        private void setNotVisitedNode(Node n) {
                if (n.getLeftChild() != null)
                        setNotVisitedNode(n.getLeftChild());
                n.visited = false;
                if (n.getRightChild() != null)
                        setNotVisitedNode(n.getRightChild());
                  n.getRightChild();
        }

        public boolean hasNext() {
                return !complete;
        }

        public T next() {
                // check if completed
                if(complete)
                        return null;

                Node tmp = p;
                p.setVisited(true);

                // next node to visit
                if (p.getLeftChild() != null && !p.getLeftChild().isVisited())
                {
                        // set p to the smallest element of the tree
                        while (p.getLeftChild() != null && !p.getLeftChild().isVisited())
                                p = p.getLeftChild();
                }
                else if (p.getRightChild() != null && !p.getRightChild().isVisited())
                {
                        p = p.getRightChild();
                        // set p to the smallest element of the tree
                        while (p.getLeftChild() != null && !p.getLeftChild().isVisited())
                                p = p.getLeftChild();
                }
                else {
                        // sub tree completed, step back or quit
                        while(p!=null && p.isVisited())
                                p=p.getParent();
                        // check for root
                        if (p==null)
                                complete=true;
                }
                // return current visited node
                return tmp.getValue();
        }

        public void remove() {

        } 
  
 }