Enum singleton versus non-capturing lambda

[Zhong Yu]

On Wed, Mar 13, 2013 at 4:51 PM, Michael Hixson
<michael.hixson at gmail.com> wrote:
> I see a couple of different forms for returning functional interface
> instances from static methods in the current lambda code.
>
> 1. Enum singleton, as in Comparators.naturalOrder()
>
>   private enum NaturalOrderComparator implements
> Comparator<Comparable<Object>> {
>     INSTANCE;
>     public int compare(Comparable<Object> c1, Comparable<Object> c2) {
>       return c1.compareTo(c2);
>     }
>   }
>
>   public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
>     return (Comparator<T>) NaturalOrderComparator.INSTANCE;
>   }
>
> 2. Non-capturing lambda, as in Functions.identity()
>
>   public static <T> Function<T, T> identity() {
>     return t -> t;
>   }
>
> Code complexity aside, does either approach have advantages over the
> other?  Does one perform better/worse or serialize better/worse?

I'd like to know too. What's the purpose of enum in the 1st example?

>
> -Michael
>