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From Henri Yandell <bay...@generationjava.com>
Subject Re: [Collections][SUBMIT] TypedList
Date Tue, 23 Apr 2002 15:55:15 GMT

Could we also have TypedMap and TypedSet?

The way I did this was:

TypedStructure interface. AbstractTypedStructure class.
IllegalTypeException exception.

Then TypedSet/List/Map implement Set/List/Map and extend
AbstractTypedStructure.

I can supply my source if you want, but as it's something I've not found
useful that often I'm guessing yours is quite a lot better.

What is the point of the wrap method?

Can I do:

    List list = TypedList(new LinkedList());   ????

Hen

On Tue, 23 Apr 2002, James Strachan wrote:

> +1
>
> this seems a good idea.
>
> James
> ----- Original Message -----
> From: "Jack, Paul" <pjack@sfaf.org>
> To: "'Jakarta Commons Developers List'" <commons-dev@jakarta.apache.org>
> Sent: Tuesday, April 23, 2002 4:14 PM
> Subject: RE: [Collections][SUBMIT] TypedList
>
>
> > Hi Steve,
> >
> > Your TypedList got me thinking...At first I thought, wouldn't
> > it be nice to specify a parameter that would allow the null
> > element (sometimes I need a list that allows nulls)...then I
> > got to thinking, actually wouldn't it be nice if the validate()
> > method could be overridden by a subclass to allow more than one
> > class type...then I thought, actually, wouldn't it be nice if
> > the validation were completely generic, so that you supplied the
> > validation routine in the constructor of the list...then I
> > realized, the collections package already defines an interface
> > for validations (Predicate)...
> >
> > So...do you think it's a good idea to alter TypedList so that it
> > takes a Predicate in its constructor?  You could then supply a
> > concrete Predicate that does the Class.isInstance check...
> >
> > -Paul
> >
> > -----Original Message-----
> > From: Stephen Colebourne [mailto:scolebourne@eurobell.co.uk]
> > Sent: Sunday, April 21, 2002 2:13 PM
> > To: Jakarta Commons Developers List
> > Subject: [Collections][SUBMIT] TypedList
> >
> >
> > Hi,
> > After a quick check, I could find no implementation of a type checking
> list
> > in collections. As I needed it, I have created one. Here is the class
> > javadoc:
> >  * TypedList is a list wrapper that supports type checking. Only elements
> >  * of the specified type (or a subclass) can be added to the list. An
> >  * attempt to add a different kind of object, or null, will cause an
> >  * <tt>IllegalArgumentException</tt>.
> >  * <p>
> >  * Constructing a new instance of this class will use an ArrayList behind
> >  * the scenes. Alternatively, the static <tt>wrap</tt> method can be
> >  * used to wrap any object implementing List.
> >
> > The code is attached as a zip. Feedback welcome on whether this is
> suitable
> > for inclusion in the collections area.
> >
> > Stephen
> >
> > --
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