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.
Inherited Method Summary
Enum Values
public static final ElementType ANNOTATION_TYPE
Annotation type declaration
public static final ElementType CONSTRUCTOR
Constructor declaration
public static final ElementType FIELD
Field declaration (includes enum constants)
public static final ElementType LOCAL_VARIABLE
Local variable declaration
public static final ElementType METHOD
Method declaration
public static final ElementType PACKAGE
Package declaration
public static final ElementType PARAMETER
Formal parameter declaration
public static final ElementType TYPE
Class, interface (including annotation type), or enum declaration
public static final ElementType TYPE_PARAMETER
Type parameter declaration
public static final ElementType TYPE_USE
Use of a type