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* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package java.lang.reflect;
import java.lang.annotation.Annotation;
import java.lang.annotation.AnnotationFormatError;
/**
* Represents an annotated element of the program currently running in this
* VM. This interface allows annotations to be read reflectively. All
* annotations returned by methods in this interface are immutable and
* serializable. The arrays returned by methods of this interface may be modified
* by callers without affecting the arrays returned to other callers.
*
*
The {@link #getAnnotationsByType(Class)} and {@link
* #getDeclaredAnnotationsByType(Class)} methods support multiple
* annotations of the same type on an element. If the argument to
* either method is a repeatable annotation type (JLS 9.6), then the
* method will "look through" a container annotation (JLS 9.7) and
* return the one or more annotations inside the container. Container
* annotations may be generated at compile-time to wrap multiple
* annotations of the argument type.
*
*
The terms directly present, indirectly present,
* present, and associated are used throughout this
* interface to describe precisely which annotations are returned by
* methods:
*
*
*
* - An annotation A is directly present on an
* element E if E has a {@code
* RuntimeVisibleAnnotations} or {@code
* RuntimeVisibleParameterAnnotations} or {@code
* RuntimeVisibleTypeAnnotations} attribute, and the attribute
* contains A.
*
*
- An annotation A is indirectly present on an
* element E if E has a {@code RuntimeVisibleAnnotations} or
* {@code RuntimeVisibleParameterAnnotations} or {@code RuntimeVisibleTypeAnnotations}
* attribute, and A 's type is repeatable, and the attribute contains
* exactly one annotation whose value element contains A and whose
* type is the containing annotation type of A 's type.
*
*
- An annotation A is present on an element E if either:
*
*
*
* - A is directly present on E; or
*
*
- No annotation of A 's type is directly present on
* E, and E is a class, and A 's type is
* inheritable, and A is present on the superclass of E.
*
*
*
* - An annotation A is associated with an element E
* if either:
*
*
*
* - A is directly or indirectly present on E; or
*
*
- No annotation of A 's type is directly or indirectly
* present on E, and E is a class, and A's type
* is inheritable, and A is associated with the superclass of
* E.
*
*
*
*
*
* For an invocation of {@code get[Declared]AnnotationsByType( Class <
* T >)}, the order of annotations which are directly or indirectly
* present on an element E is computed as if indirectly present
* annotations on E are directly present on E in place
* of their container annotation, in the order in which they appear in
* the value element of the container annotation.
* If an annotation returned by a method in this interface contains
* (directly or indirectly) a {@link Class}-valued member referring to
* a class that is not accessible in this VM, attempting to read the class
* by calling the relevant Class-returning method on the returned annotation
* will result in a {@link TypeNotPresentException}.
*
*
Similarly, attempting to read an enum-valued member will result in
* a {@link EnumConstantNotPresentException} if the enum constant in the
* annotation is no longer present in the enum type.
*
*
If an annotation type T is (meta-)annotated with an
* {@code @Repeatable} annotation whose value element indicates a type
* TC, but TC does not declare a {@code value()} method
* with a return type of T{@code []}, then an exception of type
* {@link java.lang.annotation.AnnotationFormatError} is thrown.
*
*
Finally, attempting to read a member whose definition has evolved
* incompatibly will result in a {@link
* java.lang.annotation.AnnotationTypeMismatchException} or an
* {@link java.lang.annotation.IncompleteAnnotationException}.
*
* @see java.lang.EnumConstantNotPresentException
* @see java.lang.TypeNotPresentException
* @see AnnotationFormatError
* @see java.lang.annotation.AnnotationTypeMismatchException
* @see java.lang.annotation.IncompleteAnnotationException
* @since 1.5
* @author Josh Bloch
*/
public interface AnnotatedElement {
/**
* Returns true if an annotation for the specified type
* is present on this element, else false. This method
* is designed primarily for convenient access to marker annotations.
*
*
The truth value returned by this method is equivalent to:
* {@code getAnnotation(annotationClass) != null}
*
*
The body of the default method is specified to be the code
* above.
*
* @param annotationClass the Class object corresponding to the
* annotation type
* @return true if an annotation for the specified annotation
* type is present on this element, else false
* @throws NullPointerException if the given annotation class is null
* @since 1.5
*/
default boolean isAnnotationPresent(Class extends Annotation> annotationClass) {
return getAnnotation(annotationClass) != null;
}
/**
* Returns this element's annotation for the specified type if
* such an annotation is present, else null.
*
* @param the type of the annotation to query for and return if present
* @param annotationClass the Class object corresponding to the
* annotation type
* @return this element's annotation for the specified annotation type if
* present on this element, else null
* @throws NullPointerException if the given annotation class is null
* @since 1.5
*/
T getAnnotation(Class annotationClass);
/**
* Returns annotations that are associated with this element.
*
* If there are no annotations associated with this element, the return
* value is an array of length 0.
*
* The difference between this method and {@link #getAnnotation(Class)}
* is that this method detects if its argument is a repeatable
* annotation type (JLS 9.6), and if so, attempts to find one or
* more annotations of that type by "looking through" a container
* annotation.
*
* The caller of this method is free to modify the returned array; it will
* have no effect on the arrays returned to other callers.
*
* @param the type of the annotation to query for and return if present
* @param annotationClass the Class object corresponding to the
* annotation type
* @return all this element's annotations for the specified annotation type if
* associated with this element, else an array of length zero
* @throws NullPointerException if the given annotation class is null
* @since 1.8
*/
T[] getAnnotationsByType(Class annotationClass);
/**
* Returns annotations that are present on this element.
*
* If there are no annotations present on this element, the return
* value is an array of length 0.
*
* The caller of this method is free to modify the returned array; it will
* have no effect on the arrays returned to other callers.
*
* @return annotations present on this element
* @since 1.5
*/
Annotation[] getAnnotations();
/**
* Returns this element's annotation for the specified type if
* such an annotation is directly present, else null.
*
* This method ignores inherited annotations. (Returns null if no
* annotations are directly present on this element.)
*
* @param the type of the annotation to query for and return if directly present
* @param annotationClass the Class object corresponding to the
* annotation type
* @return this element's annotation for the specified annotation type if
* directly present on this element, else null
* @throws NullPointerException if the given annotation class is null
* @since 1.8
*/
T getDeclaredAnnotation(Class annotationClass);
/**
* Returns this element's annotation(s) for the specified type if
* such annotations are either directly present or
* indirectly present. This method ignores inherited
* annotations.
*
* If there are no specified annotations directly or indirectly
* present on this element, the return value is an array of length
* 0.
*
* The difference between this method and {@link
* #getDeclaredAnnotation(Class)} is that this method detects if its
* argument is a repeatable annotation type (JLS 9.6), and if so,
* attempts to find one or more annotations of that type by "looking
* through" a container annotation.
*
* The caller of this method is free to modify the returned array; it will
* have no effect on the arrays returned to other callers.
*
* @param the type of the annotation to query for and return
* if directly or indirectly present
* @param annotationClass the Class object corresponding to the
* annotation type
* @return all this element's annotations for the specified annotation type if
* directly present on this element, else an array of length zero
* @throws NullPointerException if the given annotation class is null
* @since 1.8
*/
T[] getDeclaredAnnotationsByType(Class annotationClass);
/**
* Returns annotations that are directly present on this element.
* This method ignores inherited annotations.
*
* If there are no annotations directly present on this element,
* the return value is an array of length 0.
*
* The caller of this method is free to modify the returned array; it will
* have no effect on the arrays returned to other callers.
*
* @return annotations directly present on this element
* @since 1.5
*/
Annotation[] getDeclaredAnnotations();
}