public class LinkedSimpleIterator<E> implements SimpleIterator<E> {
  Node<E> current;
  Node<E> previous;
  Node<E> beforeprevious;
  LinkedSimpleCollection<E> coll;

  public LinkedSimpleIterator (LinkedSimpleCollection<E> coll) {
    current = coll.first;
    previous = null;
    beforeprevious = null;
    this.coll = coll;
  }

  public boolean hasNext() {
    return (current != null);
  }

  public E next() {
    if (current == null) {
      throw new java.util.NoSuchElementException();
    } else {
      if (previous != null) beforeprevious = previous;
      previous = current;
      E n = current.element;
      current = current.next;
      return n;
    }
  }

  public void remove() {
    if (previous == null) throw new IllegalStateException(); 
    else if (beforeprevious == null) coll.first = current;
    else beforeprevious.next = current;
    previous = null;
  }

}