Re: List or Iterator

From:
Lew <noone@lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Fri, 24 Jul 2009 09:36:09 -0400
Message-ID:
<h4cdca$bj0$1@news.albasani.net>
Adam Lipscombe wrote:

Are there any advantages in speed in passing a List or an Iterator as a
method parameter, or as a method return value?


No.

Any runtime reasons why one should be preferred over the other?


Yes. Also design reasons.

Iterators don't like to share. Using one as a method parameter risks
ConcurrentModificationException.

It makes perfect sense to return an Iterator if the purpose of the method is
to obtain an iterator. Such a method should be an instance method of an
'Iterable' object.

It makes little if any sense to return an iterator that is not clearly tied to
such an object. Oh, I suppose one could manufacture a use case for such a
thing, but it would be at best a corner case, or else some sort of low-level
private or package-private implementation mechanism. Typically one would want
to return an 'Iterable' (which is therefore amenable to for-each looping) or
similar.

Iterators are by nature transitory, local things. Passing them around
willy-nilly will lead to bugs.

--
Lew

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