Collections - The Java Programming Language - page 845

index of the element that a subsequent invocation of next or previous
will return. The next index when the iterator is at the end of the list is
returned as list.size() . The previous index when the iterator is at the
first element in the list (index 0 ) is returned as 1.
The remove method on a ListIterator removes the last value returned by
either next or previous . In addition to remove , you can use two additional
methods to modify the list's contents:
public void set(E elem)
Replaces the last element returned by next or previous with
elem . If you have called remove or add on the iterator since the
last call to next or previous , calling set throws IllegalStateEx-
ception . (Optional)
public void add(E elem)
Inserts elem into the list in front of the next element that
would be returned, or at the end if hasNext returns false . The
iterator is moved forward; if you invoke previous after an add
you will get the added element. (Optional)
The contract of remove is extended such that an IllegalStateException is
thrown if remove is invoked and either set or add has been invoked since
the last call to next or previous .
The contracts for Iterator and ListIterator do not include a snapshot
guarantee. In other words, changing the contents of the collection while
the iterator is in use can affect the values returned by the methods. For
example, if the implementation of next uses the contents of the original
collection for its list, it is dangerous to remove elements from the list
as you step through it except through the iterator's own methods. A
snapshot would return the elements as they were when the Iterator or
ListIterator object was created, immune from future changes. You can
rely on having a snapshot of the contents only if the method that returns
an iterator object explicitly makes a snapshot guarantee. If you need a