/* * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * 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 * by Oracle in the LICENSE file that accompanied this code. * * 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). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ 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: * *

* * 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 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(); }