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* published by the Free Software Foundation. Oracle designates this
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*
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* 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. It is permissible for the caller to modify the
* arrays returned by accessors for array-valued enum members; it will
* have no affect on the arrays returned to other callers.
*
* <p>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) which was generated at
* compile-time to wrap multiple annotations of the argument type.
*
* <p>The terms <em>directly present</em> and <em>present</em> are used
* throughout this interface to describe precisely which annotations are
* returned by methods:
*
* <ul>
* <li>An annotation A is <em>directly present</em> on an element E if E is
* associated with a RuntimeVisibleAnnotations or
* RuntimeVisibleParameterAnnotations attribute, and:
*
* <ul>
* <li>for an invocation of {@code get[Declared]Annotation(Class<T>)} or
* {@code get[Declared]Annotations()}, the attribute contains A.
*
* <li>for an invocation of {@code get[Declared]AnnotationsByType(Class<T>)}, the
* attribute either contains A or, if the type of A is repeatable, contains
* exactly one annotation whose value element contains A and whose type is the
* containing annotation type of A's type (JLS 9.6).
* </ul>
*
* <p>
* <li>An annotation A is <em>present</em> on an element E if either:
*
* <ul>
* <li>A is <em>directly present</em> on E; or
*
* <li>A is not <em>directly present</em> on E, and E is a class, and A's type
* is inheritable (JLS 9.6.3.3), and A is <em>present</em> on the superclass of
* E.
* </ul>
*
* </ul>
*
* <p>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}.
*
* <p>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.
*
* <p>Attempting to read annotations of a repeatable annotation type T
* that are contained in an annotation whose type is not, in fact, the
* containing annotation type of T, will result in an {@link
* AnnotationFormatError}.
*
* <p>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.
*
* <p>The truth value returned by this method is equivalent to:
* {@code getAnnotation(annotationClass) != null}
*
* <p>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 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 extends Annotation> T getAnnotation(Class<T> annotationClass);
/**
* Returns annotations that are <em>present</em> on this element.
*
* If there are no annotations <em>present</em> on 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 <em>repeatable
* annotation type</em> (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 annotationClass the Class object corresponding to the
* annotation type
* @return all this element's annotations for the specified annotation type if
* present on this element, else an array of length zero
* @throws NullPointerException if the given annotation class is null
* @since 1.8
*/
<T extends Annotation> T[] getAnnotationsByType(Class<T> annotationClass);
/**
* Returns annotations that are <em>present</em> on this element.
*
* If there are no annotations <em>present</em> 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 present, else null.
*
* This method ignores inherited annotations. (Returns null if no
* annotations are directly present on this element.)
*
* @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 1.8
*/
<T extends Annotation> T getDeclaredAnnotation(Class<T> annotationClass);
/**
* Returns annotations that are <em>directly present</em> on this element.
* This method ignores inherited annotations.
*
* If there are no annotations <em>directly present</em> 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 <em>repeatable annotation type</em> (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 annotationClass the Class object corresponding to the
* annotation type
* @return all this element's annotations for the specified annotation type if
* present on this element, else an array of length zero
* @throws NullPointerException if the given annotation class is null
* @since 1.8
*/
<T extends Annotation> T[] getDeclaredAnnotationsByType(Class<T> annotationClass);
/**
* Returns annotations that are <em>directly present</em> on this element.
* This method ignores inherited annotations.
*
* If there are no annotations <em>directly present</em> 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();
}