Enum ElementType
- java.lang.Object
-
- java.lang.Enum<ElementType>
-
- java.lang.annotation.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 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
Enum Constant Summary
| 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 declared in class java.lang.Enum
clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf Methods declared in class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait 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