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From Henri Yandell <>
Subject Re: [COLLECTIONS] Some more lobbying for the OrderedSet class
Date Thu, 17 Apr 2003 18:58:17 GMT

Feel free to go ahead. While I'd love to try and make Collections
feel simpler to me [and hopefully everyone else?], Lang and Taglibs are
both taking priority for me at the moment.

Just as long as the implementation of OrderedSet and UniqueList, or just
ListSet if the interfaces may be combined, does not force the usage of a
particular underlying implementation, then I'm +1 :)

Does it make sense to have a ListSet that implements both interfaces? A
join as such. Set as an interface is a superclass API-wise of List [or
could be]. The only difference is that Set has a contract of uniqueness.

My head is hurting from humidity [why oh why did I move to the US Deep
South], but it seems that:

UniqueList extends ProxyList implements Set

makes a lot of sense here?

If I have an ordered-set, is there any reason why I would not want the
extra methods from the List API? The only reason I can think of is that I
might not want to deal with the extra coding.

Oh, one other reason comes from wrappability. UniqueList makes it obvious
that it is going to wrap a List and just implement some contractual checks
to stop checking things in. How would a UniqueList wrap a Set? Or
OrderedSet if we want to call it that while considering it in Set context.
Assuming you've implemented it similar to how I implemented my own
OrderedSet, as an ArrayList that pretends to be a Set, I think that
OrderedSet is the wrong name and UniqueList is better.

Another question that has probably been asked, is why don't we just have a
method on CollectionUtils which returns a PredicateList with a
UniquePredicate that is called:   createUniqueList/createOrderedSet?

I guess I'm still trying to boil the Jakarta Collections API down to a
series of basic tenets.

Sorry for babbling,


On Thu, 17 Apr 2003 wrote:

> FYI, I support the adding of OrderedSet to [collections]. I have held
> off because Henri made some indications that he was going to add full
> support for this concept as a decorator. I didn't want two competing
> implementations. Henri??
> (LinkedHashSet is JDK1.4, so is only relevant for [collections]
> discussions as an aside. I don't think you can get the class for
> earlier JDKs.)
> Stephen
> >  from:    "Henning P. Schmiedehausen" <>
> >  date:    Thu, 17 Apr 2003 10:01:10
> >  to:
> >  subject: Re: [COLLECTIONS] Some more lobbying for the OrderedSet class
> >
> > Emmanuel Bourg <> writes:
> >
> > >--------------ms050704090404060703060209
> > >Content-Type: text/plain; charset=us-ascii; format=flowed
> > >Content-Transfer-Encoding: 7bit
> >
> > >What's the difference with the behaviour of the LinkedHashSet ?
> >
> > Hi,
> >
> > didn't know about that one, right. Its properties sound like the
> > OrderedSet, right. However, it is JDK 1.4 only and at least for
> > Turbine and Torque we won't go 1.4 only (yet).
> >
> > Do you know whether there is an "addon" package from Sun containing
> > this class available for JDK 1.3 ?
> >
> > 	Regards
> > 		Henning
> >
> > --
> > Dipl.-Inf. (Univ.) Henning P. Schmiedehausen          INTERMETA GmbH
> >         49 9131 50 654 0
> >
> > Java, perl, Solaris, Linux, xSP Consulting, Web Services
> > freelance consultant -- Jakarta Turbine Development  -- hero for hire
> >
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