Galder, what JDK are you using? OpenJDK 1.7 uses EmptyIterator.EMPTY_ITERATOR since 2007:

http://hg.openjdk.java.net/jdk7/jdk7/jdk/annotate/37a05a11f281/src/share/classes/java/util/Collections.java

I don't have JDK 1.6 sources on hand to check, but I don't think it's worth optimizing for such an old version anyway.

Cheers
Dan


On Fri, Oct 19, 2012 at 5:50 PM, Vladimir Blagojevic <vblagoje@redhat.com> wrote:
Cool! Did not know about this! Is this original idea or others are
already doing this?
On 12-10-19 8:31 AM, Galder Zamarreņo wrote:
> Hi all,
>
> Re: https://github.com/galderz/infinispan/commit/0609207d13216de81d77ff51dc20652ce270c635
>
> Please avoid using these JDK methods where possible. I've created alternative versions in InfinispanCollections util class that provide a better implementation.
>
> The problem with the JDK versions is that even if these collections are immutable, if you wanna iterate them (i.e. for(X : emptySet) ), they'll create a brand new Iterator every time they're looped, and that generates useless garbage.
>
> The InfinispanCollections versions of emptyX will return a constant singleton iterator which avoids this problem, and avoids the need for client code to check if the collection is empty before looping.
>
> Cheers,
> --
> Galder Zamarreņo
> galder@redhat.com
> twitter.com/galderz
>
> Project Lead, Escalante
> http://escalante.io
>
> Engineer, Infinispan
> http://infinispan.org
>
>
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