Java - Should an iterator for a doubly linked list with sentinels look like this?

I'm writing my own implementation of a doubly linked list as an exercise, but I don't think I fully understand how to utilize the sentinel nodes at the start and end of the list. I would like to ask about using sentinels in the iterator in particular. Here's my iterator (not finished):

private class MyIterator implements Iterator<T> {
    private Node current = first;

    public boolean hasNext() {
        if(current.next.next == null) return false;
        else return true;
    }

    public T next() {
        current = current.next;
        if(current.next == null) throw new NoSuchElementException();
        return current.data;
    }
}

What I want to know is if there's any way I can utilize the tail sentinel in the next() and hasNext() methods to avoid null checks. Or is this fine as it is?