Hi Gunnar,
Annotations went into the platform way back in Java SE 5.0, with a GA
during 2004. When working on repeating annotations, I was surprised to
find there weren't stronger ordering guarantees for annotations from
core reflection. However, requests to tighten this aspect of the
platform haven't come up very often in the interim and I don't like it
is likely to happen at this point.
HTH,
-Joe
On 1/17/2017 11:26 PM, Gunnar Morling wrote:
Joseph, all,
Thanks for the clarification.
Are there chances to establish such guaranteed ordering in a future
Java version? As pointed out, it'd be very helpful to Bean Validation
and I reckon other cases, too.
Thanks,
--Gunnar
2017-01-18 3:13 GMT+01:00 Joseph D. Darcy <joe.da...@oracle.com>:
Hello,
Following up on Joel's message, IIRC this ordering issue did come up during
the design and testing of repeating annotations.
As noted previously in the thread, while the ordering of the annotations in
a container annotation is guaranteed, there is *not* a general ordering
constraint on the annotations returned by the methods of the
AnnotatedElement interface.
HTH,
-Joe
On 1/13/2017 1:16 PM, Gunnar Morling wrote:
Hi Yuri,
Thanks for the pointer.
But do you see any clear description of an order mandated for
getDeclaredAnnotations()? The only references to an order I can find
there are for repeatable annotations (where source code order is
maintained when retrieving them via the container annotation type).
But I cannot find any guaranteed order when obtaining all declared
annotations from an element.
The reason why I'm asking is Bean Validation, where we've seen
requests of people that wish to validate the constraints of an element
in a fixed order, aborting after the first failed constraint:
@NotNull
@Email
String email;
Here one may want to first validate @NotNull and don't proceed with
validating @Email if the field is null.
Relying on source order would be a very natural way to express the
order of constraints. Without a guaranteed ordering of annotations
we'd have to add some other means of ordering, e.g. an attribute with
the index (@NotNull(order=0) @Email(order=1)) which is more verbose of
course.
--Gunnar
2017-01-13 21:15 GMT+01:00 Yuri Gaevsky <ygaev...@azulsystems.com>:
Hi Gunnar,
Please take a look at JDK-8010679 'Clarify "present" and annotation
ordering in Core Reflection for Annotations' [*].
Best regards,
-Yuri
[*] https://bugs.openjdk.java.net/browse/JDK-8010679
-----Original Message-----
From: core-libs-dev [mailto:core-libs-dev-boun...@openjdk.java.net] On
Behalf Of Gunnar Morling
Sent: Friday, January 13, 2017 08:14 PM
To: core-libs-dev@openjdk.java.net
Subject: Guaranteed order of annotations?
Hi,
Is there any order guaranteed in which an element's annotations are
returned by AnnotatedElement#getDeclaredAnnotations()? Specifically,
is this the order in which the annotations are given in the source
code?
Section 9.7.5. of the JLS ("Multiple Annotations of the Same Type")
makes a statement of the source order being considered by the array of
the implicit container annotation created for a repeatable annotation
("[...] all the base annotations in the left-to-right order in which
they appeared in the context").
But I couldn't find any authoritative description on the ordering
behaviour of getDeclaredAnnotations(). Should we assume that we cannot
rely on the order in the source?
Thanks for any pointers,
--Gunnar
