Kotlin Annotations Declaring an annotation


Annotations are means of attaching metadata to code. To declare an annotation, put the annotation modifier in front of a class:

annotation class Strippable

Annotations can have meta-anotations:

    @Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.VALUE_PARAMETER, AnnotationTarget.EXPRESSION)
    annotation class Strippable

Annotations, like other classes, can have constructors:

annotation class Strippable(val importanceValue: Int)

But unlike other classes, is limited to the following types:

  • types that correspond to Java primitive types (Int, Long etc.);
  • strings
  • classes ( Foo:: class)
  • enums
  • other annotations
  • arrays of the types listed above