Como faço para implementar DoublyLinkedListIterator em java

Programação Java
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#1 
private class DoublyLinkedListIterator implements ListIterator<E> {

        private DoublyLinkedList.Node<E> nextNode, prevNode, lastReturnedNode; // node that will be returned using next and prev respectively
        private int nextIndex;  // Index of the next element
        private int expectedModCount;  // Expected number of modifications = modCount;

        public DoublyLinkedListIterator() {
            this.prevNode = header;
            this.nextNode = header.getNext();
            lastReturnedNode = null;
            nextIndex = 0;
            expectedModCount = modCount;
        }

        final void checkForComodification() {  // invalidate iterator on list modification outside the iterator
            if (modCount != expectedModCount) {
                throw new ConcurrentModificationException();
            }
        }

        @Override
        public boolean hasNext() {
            throw new UnsupportedOperationException("Not supported yet.");
        }

        @Override
        public E next() throws NoSuchElementException {
            checkForComodification();

          throw new UnsupportedOperationException("Not supported yet.");
        }

        @Override
        public boolean hasPrevious() {
              throw new UnsupportedOperationException("Not supported yet.");
        }

        @Override
        public E previous() throws NoSuchElementException {
            checkForComodification();
            throw new UnsupportedOperationException("Not supported yet.");
        }

        @Override
        public int nextIndex() {
             throw new UnsupportedOperationException("Not supported yet.");
        }

        @Override
        public int previousIndex() {
            throw new UnsupportedOperationException("Not supported yet.");
        }

        @Override
        public void remove() throws NoSuchElementException {
            checkForComodification();

            throw new UnsupportedOperationException("Not supported yet.");
        }

        @Override
        public void set(E e) throws NoSuchElementException {
            if (lastReturnedNode == null) {
                throw new NoSuchElementException();
            }
            checkForComodification();

            lastReturnedNode.setElement(e);
        }

        @Override
        public void add(E e) {
            checkForComodification();

            throw new UnsupportedOperationException("Not supported yet.");
        }

    }    //----------- end of inner DoublyLinkedListIterator class ----------

//---------------- Iterable implementation ----------------