public void printTree() {
	printTree2(root);
	System.out.println();
    }

    private void printTree2(Node tree) {
	if (tree != null) {
	    System.out.print(tree.getKey() + " ");
            if (tree.getLeft() != null)
	        System.out.print("Left: " + tree.getLeft().getKey() + " ");
            else
                System.out.print("Left: null ");
            if (tree.getRight() != null)
	        System.out.println("Right: " + tree.getRight().getKey() + " ");
            else
                System.out.println("Right: null ");
	    printTree2(tree.getLeft());
	    printTree2(tree.getRight());
	}
    }