On 03/27/2013 03:00 PM, Peter Levart wrote:
On 03/27/2013 02:00 PM, Joel Borggrén-Franck wrote:
Hi Peter,
On 03/27/2013 01:31 PM, Peter Levart wrote:
I also don't know
whether having LinkedHashMap instead of plain HashMap is necessary, since it
is initialized with defaults from plain HashMap (which is hashCode %
capacity ordered) and only some of defaults are overridden in parsing loop
in general. For example, having this annotation:
@interface Ann {
String one();
String two() default "2";
}
and usage:
@Ann(one = "1")
...toString will print: @Ann(two = "2", one = "1")
While there perhaps is no natural ordering between the sets of default
elements and non-default elements you probably want an order following
source as closely as possible among the non-default elements.
What is the order of elements in java class file (the bytes that the parser
interprets)? Is it taken from the declaration of annotation (the order of
methods in annotation interface) or from the use-site of the annotation? Is
this specified?
In general javac tries to keep source order on "things" when emitting to a
class file. I believe this is often specified as natural order, but don't
trust me on this. In this specific case I would guess element use order from
the annotatio instance.
In the following small example I note that 'b' comes before 'a' in the const
pool but the RuntimeInvisibleAnnotations 'a' is before 'b'. I don't think
this is a coincidence.
anno-order$ cat T.java
@T(a="XYZ", b="DEF")
public @interface T {
String b();
String a();
}
anno-order$ javap -v T.class
Classfile /localhome/src/test/anno-order/T.class
Last modified Mar 27, 2013; size 239 bytes
MD5 checksum e1c7d8d76842d219c9853463af37830a
Compiled from "T.java"
public interface T extends java.lang.annotation.Annotation
SourceFile: "T.java"
RuntimeInvisibleAnnotations:
0: #10(#6=s#11,#4=s#12)
minor version: 0
major version: 52
flags: ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT, ACC_ANNOTATION
Constant pool:
#1 = Class #13 // T
#2 = Class #14 // java/lang/Object
#3 = Class #15 // java/lang/annotation/Annotation
#4 = Utf8 b
#5 = Utf8 ()Ljava/lang/String;
#6 = Utf8 a
#7 = Utf8 SourceFile
#8 = Utf8 T.java
#9 = Utf8 RuntimeInvisibleAnnotations
#10 = Utf8 LT;
#11 = Utf8 XYZ
#12 = Utf8 DEF
#13 = Utf8 T
#14 = Utf8 java/lang/Object
#15 = Utf8 java/lang/annotation/Annotation
For more examples of order discussions see the recent discussion on
enhanced-metadata-spec-disc...@openjdk.java.net on annotation ordering in
reflection and javax.lang.model.
cheers
/Joel
