Java Reference
In-Depth Information
Note that the at-sign (
@
) and the keyword
interface
are two distinct tokens. Technically
it is possible to separate them with whitespace, but this is discouraged as a matter of
style.
AnnotationTypeDeclaration:
InterfaceModifiers
opt
@ interface
Identifier AnnotationTypeBody
AnnotationTypeBody:
{
AnnotationTypeElementDeclarations
opt
}
AnnotationTypeElementDeclarations:
AnnotationTypeElementDeclaration
AnnotationTypeElementDeclarations AnnotationTypeElementDeclaration
type
T
, and
T
has a (meta-)annotation
m
that corresponds to
java.lang.annotation.Target
, then
m
must have either an element whose value is
java.lang.annotation.ElementType.ANNOTATION_TYPE
, or an element whose value is
java.lang.annotation.ElementType.TYPE
, or a compile-time error occurs.
The
Identifier
in an annotation type declaration specifies the name of the annotation type.
It is a compile-time error if an annotation type has the same simple name as any of its en-
closing classes or interfaces.
The direct superinterface of an annotation type is always
java.lang.annotation.Annotation
.
By virtue of the
AnnotationTypeDeclaration
syntax, an annotation type declaration
cannot be generic, and no
extends
clause is permitted.
A consequence of the fact that an annotation type cannot explicitly declare a super-
class or superinterface is that a subclass or subinterface of an annotation type is never
itself an annotation type. Similarly,
java.lang.annotation.Annotation
is not itself an annota-
tion type.
An annotation type declaration inherits several members from
java.lang.annotation.Annotation
,
including the implicitly declared methods corresponding to the instance methods in
Object
,
yet these methods do not define elements (§
9.6.1
) of the annotation type and it is illegal to
use them in annotations.
Without this rule, we could not ensure that the elements were of the types represent-
able in annotations, or that accessor methods for them would be available.
Unless explicitly modified herein, all of the rules that apply to ordinary interface declara-
tions apply to annotation type declarations.
