default methods inherited by EnumSet and EnumMap

Martin Buchholz martinrb at
Tue Dec 6 17:53:25 UTC 2016

Almost every core library collection class can benefit from overriding
those default methods for performance.
But it hasn't been done consistently - I noticed this myself recently in
other collection classes; we have an effort under way to fix that for jdk9
(notably ArrayDeque).  But EnumMap/EnumSet have probably fallen into the
orphaned bucket.

On Tue, Dec 6, 2016 at 12:03 AM, Michael Hixson <michael.hixson at>

> Hello,
> I notice that EnumSet and EnumMap don't override any of the default
> methods that were added to collections in Java 8.  Were they
> specifically considered then avoided during the Java 8 upgrades, or
> was it simply that no one got around to optimizing them?  Are there
> existing issues/bugs for optimizing them?  I couldn't find any.
> As one example:  I suspect that EnumMap.forEach(action) could improve
> a lot.  Right now it looks like iterating over keySet() and calling
> get(key) is faster than forEach(action) when it comes to EnumMap
> (unlike every other Map implementation I tested).
> -Michael

More information about the core-libs-dev mailing list