Re: List or Iterator

From:
"Mike Schilling" <mscottschilling@hotmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Mon, 27 Jul 2009 10:43:57 -0700
Message-ID:
<h4kpe5$7a3$1@news.eternal-september.org>
Tom Anderson wrote:

On Sun, 26 Jul 2009, Mike Schilling wrote:

Andreas Leitgeb wrote:

Mike Schilling <mscottschilling@hotmail.com> wrote:

Lew wrote:

Andreas Leitgeb wrote:

In Java, the solution to this usually boils down to anonymous
classes: Iterable<Node> getChildrenIterable() {
       final Iterator<Node> it= getChildrenIterator();
       return new Iterable<Node>() {
           public Iterator<Node> iterator() { return it; }
       }
   }
(untested!)

Naturally the anonymity is a tangential detail. It's trivial to
give such a class a name, just not usually necessary.

Exactly.

Speaking of which, a semi-tangential question: has anyone ever
found a use for a local class (i.e, a class defined inside a
method, just like an anonymous class, but given a name)? I never
have.


I haven't yet had a use for it myself, but I could think of a few:

1) An aesthetic tradeoff: you give that class a name, and in
return
  you avoid having a line without the "class" keyword but followed
by
  a class-body.
2) with a named class you can also have your own constructor with
  parameters, while still sugar'ing away the need to pass finals
explicitly. 3) One may instantiate the same class at multiple
places
  within the same method. (e.g. for a couple of switch-cases.)


All good points. Of course, when any of them apply, you've also
got
to consider "Might I want to use this class in another method? If
so, I might as well make it a full-fledged nested class." Anyway,
had local classes never been invented, I doubt we'd miss them.


I didn't realise we did have them! When were they added?


Long ago, at the same time as anonymous classes.

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