A UniqueList is a List which rejects duplicate elements (recall that the
modification methods on List, add/add/addAll/addAll/set, are permitted
throw IllegalArgumentException if there's anything they don't like about
the offered element(s)). The same goes for the modification methods on the
list's listIterator().
The nice thing about this restriction is that a UniqueList can be viewed as
a Set in a completely "read-through, write-through" fashion. So the
UniqueList<E> interface would extend List<E> to add this asSet() method. I
don't believe that any subtype of Set is needed for this; AFAIK it just
needs regular Set methods and not much else.
As well, the subList() method could be refined so that it also returns a
UniqueList<E>. Of course, the sublist would throw IAE in response to any
operation that would result in a duplicate element in the *parent* list.
An AbstractUniqueList<E> class could be provided which only needs the
implementing class to supply a backing List and a backing Set, and
optionally override a few methods for better performance.
Unfortunately, the Collections methods sort(), shuffle(), reverse() and
swap() would fail on a UniqueList. They all make the assumption that the
list being acted upon has no problem with temporarily containing the same
element twice. There's nothing we can do about that -- it's the price you pay.
Original issue reported on code.google.com by kevin...@gmail.com on 23 Oct 2007 at 4:14
Original issue reported on code.google.com by
kevin...@gmail.comon 23 Oct 2007 at 4:14