java.lang.annotation

Enum ElementType

  • All Implemented Interfaces:
    Serializable, Comparable<ElementType> 

    public enum ElementType
extends Enum<ElementType>
    The constants of this enumerated type provide a simple classification of the syntactic locations where annotations may appear in a Java program. These constants are used in java.lang.annotation.Target meta-annotations to specify where it is legal to write annotations of a given type.

    The syntactic locations where annotations may appear are split into declaration contexts , where annotations apply to declarations, and type contexts , where annotations apply to types used in declarations and expressions.

    The constants ANNOTATION_TYPE , CONSTRUCTOR , FIELD , LOCAL_VARIABLE , METHOD , PACKAGE , PARAMETER , TYPE , and TYPE_PARAMETER correspond to the declaration contexts in JLS 9.6.4.1.

    For example, an annotation whose type is meta-annotated with @Target(ElementType.FIELD) may only be written as a modifier for a field declaration.

    The constant TYPE_USE corresponds to the 15 type contexts in JLS 4.11, as well as to two declaration contexts: type declarations (including annotation type declarations) and type parameter declarations.

    For example, an annotation whose type is meta-annotated with @Target(ElementType.TYPE_USE) may be written on the type of a field (or within the type of the field, if it is a nested, parameterized, or array type), and may also appear as a modifier for, say, a class declaration.

    The TYPE_USE constant includes type declarations and type parameter declarations as a convenience for designers of type checkers which give semantics to annotation types. For example, if the annotation type NonNull is meta-annotated with @Target(ElementType.TYPE_USE), then @NonNull class C {...} could be treated by a type checker as indicating that all variables of class C are non-null, while still allowing variables of other classes to be non-null or not non-null based on whether @NonNull appears at the variable's declaration.

    Since:
    1.5

    • Enum Constant Detail

      • TYPE

        public static final ElementType TYPE
        Class, interface (including annotation type), or enum declaration

      • FIELD

        public static final ElementType FIELD
        Field declaration (includes enum constants)

      • METHOD

        public static final ElementType METHOD
        Method declaration

      • PARAMETER

        public static final ElementType PARAMETER
        Formal parameter declaration

      • CONSTRUCTOR

        public static final ElementType CONSTRUCTOR
        Constructor declaration

      • LOCAL_VARIABLE

        public static final ElementType LOCAL_VARIABLE
        Local variable declaration

      • ANNOTATION_TYPE

        public static final ElementType ANNOTATION_TYPE
        Annotation type declaration

      • PACKAGE

        public static final ElementType PACKAGE
        Package declaration

      • TYPE_PARAMETER

        public static final ElementType TYPE_PARAMETER
        Type parameter declaration
        Since:
        1.8

      • TYPE_USE

        public static final ElementType TYPE_USE
        Use of a type
        Since:
        1.8

    • Method Detail

      • values

        public static ElementType[] values()
        Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows: 
        for (ElementType c : ElementType.values())
    System.out.println(c);
        Returns:
        an array containing the constants of this enum type, in the order they are declared

      • valueOf

        public static ElementType valueOf(String name)
        Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
        Parameters:
        name - the name of the enum constant to be returned.
        Returns:
        the enum constant with the specified name
        Throws:
        IllegalArgumentException - if this enum type has no constant with the specified name
        NullPointerException - if the argument is null