AnnotatedConstruct (Java Platform SE 8 )
Keywords: javax.lang.model.AnnotatedConstruct interface
Date: 2015-05-24

compact3
javax.lang.model

## Interface AnnotatedConstruct

- All Known Subinterfaces:
    ArrayType, DeclaredType, Element, ErrorType, ExecutableElement, ExecutableType, IntersectionType, NoType, NullType, PackageElement, Parameterizable, PrimitiveType, QualifiedNameable, ReferenceType, TypeElement, TypeMirror, TypeParameterElement, TypeVariable, UnionType, VariableElement, WildcardType

      public interface AnnotatedConstruct

  Represents a construct that can be annotated. A construct is either an element or a type. Annotations on an element are on a declaration, whereas annotations on a type are on a specific use of a type name. The terms directly present, present, indirectly present, and associated are used throughout this interface to describe precisely which annotations are returned by the methods defined herein.

  In the definitions below, an annotation A has an annotation type AT. If AT is a repeatable annotation type, the type of the containing annotation is ATC.

  Annotation A is directly present on a construct C if either:

  - A is explicitly or implicitly declared as applying to the source code representation of C.

    Typically, if exactly one annotation of type AT appears in the source code of representation of C, then A is explicitly declared as applying to C. If there are multiple annotations of type AT present on C, then if AT is repeatable annotation type, an annotation of type ATC is implicitly declared on C.

  - A representation of A appears in the executable output for C, such as the `RuntimeVisibleAnnotations` or `RuntimeVisibleParameterAnnotations` attributes of a class file.

  An annotation A is present on a construct C if either:

  - A is directly present on C.
  - No annotation of type AT is directly present on C, and C is a class and AT is inheritable and A is present on the superclass of C.
  An annotation A is indirectly present on a construct C if both:
  - AT is a repeatable annotation type with a containing annotation type ATC.
  - An annotation of type ATC is directly present on C and A is an annotation included in the result of calling the `value` method of the directly present annotation of type ATC.
  An annotation A is associated with a construct C if either:
  - A is directly or indirectly present on C.
  - No annotation of type AT is directly or indirectly present on C, and C is a class, and AT is inheritable, and A is associated with the superclass of C.
  Since:
    1.8
  See The Java™ Language Specification:
    9.6 Annotation Types, 9.6.3.3 @Inherited

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `<A extends Annotation> A` | `getAnnotation(Class<A> annotationType)` Returns this construct's annotation of the specified type if such an annotation is present, else `null`.
    `List<? extends AnnotationMirror>` | `getAnnotationMirrors()` Returns the annotations that are directly present on this construct.
    `<A extends Annotation> A[]` | `getAnnotationsByType(Class<A> annotationType)` Returns annotations that are associated with this construct.

- - ### Method Detail

    - #### getAnnotationMirrors

          List<? extends AnnotationMirror> getAnnotationMirrors()

      Returns the annotations that are directly present on this construct.
      Returns:
        the annotations directly present on this construct; an empty list if there are none

    - #### getAnnotation

          <A extends Annotation> A getAnnotation(Class<A> annotationType)

      Returns this construct's annotation of the specified type if such an annotation is present, else `null`.

      The annotation returned by this method could contain an element whose value is of type `Class`. This value cannot be returned directly: information necessary to locate and load a class (such as the class loader to use) is not available, and the class might not be loadable at all. Attempting to read a `Class` object by invoking the relevant method on the returned annotation will result in a `MirroredTypeException`, from which the corresponding `TypeMirror` may be extracted. Similarly, attempting to read a `Class[]`-valued element will result in a `MirroredTypesException`.

      > Note: This method is unlike others in this and related interfaces. It operates on runtime reflective information — representations of annotation types currently loaded into the VM — rather than on the representations defined by and used throughout these interfaces. Consequently, calling methods on the returned annotation object can throw many of the exceptions that can be thrown when calling methods on an annotation object returned by core reflection. This method is intended for callers that are written to operate on a known, fixed set of annotation types.

      Type Parameters:
        `A` - the annotation type
      Parameters:
        `annotationType` - the `Class` object corresponding to the annotation type
      Returns:
        this construct's annotation for the specified annotation type if present, else `null`
      See Also:
        `getAnnotationMirrors()`, `AnnotatedElement.getAnnotation(java.lang.Class<T>)`, `EnumConstantNotPresentException`, `AnnotationTypeMismatchException`, `IncompleteAnnotationException`, `MirroredTypeException`, `MirroredTypesException`
      See The Java™ Language Specification:
        9.6.1 Annotation Type Elements

    - #### getAnnotationsByType

          <A extends Annotation> A[] getAnnotationsByType(Class<A> annotationType)

      Returns annotations that are associated with this construct. If there are no annotations associated with this construct, the return value is an array of length 0. The order of annotations which are directly or indirectly present on a construct C is computed as if indirectly present annotations on C are directly present on C in place of their container annotation, in the order in which they appear in the value element of the container annotation. The difference between this method and `getAnnotation(Class)` is that this method detects if its argument is a repeatable annotation type, and if so, attempts to find one or more annotations of that type by "looking through" a container annotation.

      The annotations returned by this method could contain an element whose value is of type `Class`. This value cannot be returned directly: information necessary to locate and load a class (such as the class loader to use) is not available, and the class might not be loadable at all. Attempting to read a `Class` object by invoking the relevant method on the returned annotation will result in a `MirroredTypeException`, from which the corresponding `TypeMirror` may be extracted. Similarly, attempting to read a `Class[]`-valued element will result in a `MirroredTypesException`.

      > Note: This method is unlike others in this and related interfaces. It operates on runtime reflective information — representations of annotation types currently loaded into the VM — rather than on the representations defined by and used throughout these interfaces. Consequently, calling methods on the returned annotation object can throw many of the exceptions that can be thrown when calling methods on an annotation object returned by core reflection. This method is intended for callers that are written to operate on a known, fixed set of annotation types.

      Type Parameters:
        `A` - the annotation type
      Parameters:
        `annotationType` - the `Class` object corresponding to the annotation type
      Returns:
        this construct's annotations for the specified annotation type if present on this construct, else an empty array
      See Also:
        `getAnnotationMirrors()`, `getAnnotation(Class)`, `AnnotatedElement.getAnnotationsByType(Class)`, `EnumConstantNotPresentException`, `AnnotationTypeMismatchException`, `IncompleteAnnotationException`, `MirroredTypeException`, `MirroredTypesException`
      See The Java™ Language Specification:
        9.6 Annotation Types, 9.6.1 Annotation Type Elements

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