public void levelPrint() { //breadth first BFS
		QueueList queue = new QueueList ();
		queue.enqueue(this);
		while (queue.getSize()!=0) {
			TreeNode node = (TreeNode) queue.dequeue();
			if (node.left!=null) queue.enqueue(node.left);
			if (node.right!=null) queue.enqueue(node.right);
			System.out.println(node.getData());
		}
		
	}