Package java.lang.annotation

Enum ElementType

java.lang.Object

java.lang.Enum<ElementType>

java.lang.annotation.ElementType

All Implemented Interfaces:

Serializable, Comparable<ElementType>, Modified

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 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, MODULE, 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 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

Author:

Joshua Bloch

Enum Constant Summary

Enum Constants

Enum Constant	Description
ANNOTATION_TYPE	Annotation type declaration
CONSTRUCTOR	Constructor declaration
FIELD	Field declaration (includes enum constants)
LOCAL_VARIABLE	Local variable declaration
METHOD	Method declaration
MODULE	Module declaration.
PACKAGE	Package declaration
PARAMETER	Formal parameter declaration
TYPE	Class, interface (including annotation type), or enum declaration
TYPE_PARAMETER	Type parameter declaration
TYPE_USE	Use of a type

Method Summary

Modifier and Type	Method	Description
static ElementType	valueOf(String name)	Returns the enum constant of this type with the specified name.
static ElementType[]	values()	Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

compareTo, equals, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass

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

MODULE

public static final ElementType MODULE

Module declaration.

Since:

9

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