class TreeNode {
public:
	Object obj;
	TreeNode *leftChild;
	TreeNode *rightChild;

private:
	Object getObject() {
		return obj;
	}

	TreeNode* getleftChild() {
		return leftChild;
	}

	TreeNode* getRightChild() {
		return rightChild;
	}
}


class Tree {
private:
    TreeNode *root;

public:
    TreeNode* getRoot() {return root};
    void inOrderPrint() {inOrderPrint(root)};

    void inOrderPrint(TreeNode *toPrint) {
		TreeNode *left = toPrint->getLeftChild();
		TreeNode *right = toPrint->getRightChild();
		if(left != null)
		  inOrderPrint(left);
		toPrint->getObject().print();
		if(right != null)
		  inOrderPrint(right);
    }

};

...

Tree *t = ...;
//insertions
t->inOrderPrint();
//OR
t->inOrderPrint(t->getRoot());