Target

Target

Target(vararg value: ElementType)

Indicates the contexts in which an annotation interface is applicable. The declaration contexts and type contexts in which an annotation interface may be applicable are specified in JLS {@jls 9.6.4.1}, and denoted in source code by enum constants of java.lang.annotation.ElementType.

If an @Target meta-annotation is not present on an annotation interface T, then an annotation of type T may be written as a modifier for any declaration.

If an @Target meta-annotation is present, the compiler will enforce the usage restrictions indicated by ElementType enum constants, in line with JLS {@jls 9.7.4}.

For example, this @Target meta-annotation indicates that the declared interface is itself a meta-annotation interface. It can only be used on annotation interface declarations:

@Target(ElementType.ANNOTATION_TYPE)
     public @interface MetaAnnotationType {
         ...
     }
  

This @Target meta-annotation indicates that the declared class or interface is intended solely for use as a member class or interface in complex annotation interface declarations. It cannot be used to annotate anything directly:

@Target({})
     public @interface MemberInterface {
         ...
     }
  

It is a compile-time error for a single ElementType constant to appear more than once in an @Target annotation. For example, the following @Target meta-annotation is illegal:

@Target({ElementType.FIELD, ElementType.METHOD, ElementType.FIELD})
     public @interface Bogus {
         ...
     }
  

value

val value: Array<ElementType>

Returns an array of the kinds of elements an annotation interface can be applied to.