template <typename> class List;   // required forward declaration

template <typename T>
class ListIterator
{

  friend class List<T>;

  public:
    ListIterator();
    bool hasNext() const;
    bool hasPrevious() const;
    T &next() throw ( NoSuchObject );
    T &previous() throw ( NoSuchObject );
    void printInternal() const;

  private:
    Node<T> *current;
    bool before;

};