Re: what is encapsulation in an interface ?

From:

"Mike Schilling" <mscottschilling@hotmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 2 Jan 2011 08:51:46 -0800

Message-ID:

<ifqaf2$4bp$1@news.eternal-september.org>

"Chris Uppal" <chris.uppal@hotmail.REMOVE-THIS.co.uk> wrote in message
news:mqadnV_KF_JGy73QnZ2dnUVZ8mCdnZ2d@bt.com...

If the canned stuff were powerful enough to be of really general use (so
that, in fact, there was very rarely a reason to write "raw" loops -- as
is the case with the Smalltalk collections hierarchy for instance), then
the canned stuff, /because/ it's idiomatic, becomes the clearer option.
But for that to happen, the canned stuff has to be a lot more expressive
than that provided by java.util.Collection: I'm still trying to think of a
valid reason for such a very special-purpose routine as
java.util.Collection.frequency() to exist at all. Now if there were a way
to say "for instances of X in this collection do [... such and such ...]",
then Ken's original example would be made clearer than either of the
options that are actually available. Something like (invented crap
syntax):
   int count = 0;
   for (Object o: list: {o == null})
       count++;
which retains the possibility of efficient implementation, clearly
expresses what we are trying to do, and doesn't depend on some extremely
specialised (absurdly over-specialised, IMO) routine happening to exist.

As has been pointed out, you can do this sort of thing in C#. You could
build it in Java too, but since the expression would have to be specified as
a method in an anonymous class. it would amount to obfuscation, the result
being something like

count = Collections.getFilteredCollection(list, new Filter()
                {
                    @Override
                    public boolean accept(Object member)
                    {
                        return member == null;
                    }
                }).size();