1 /* 2 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang.reflect; 27 28 import java.lang.annotation.Annotation; 29 30 /** 31 * Represents an annotated element of the program currently running in this 32 * VM. This interface allows annotations to be read reflectively. All 33 * annotations returned by methods in this interface are immutable and 34 * serializable. It is permissible for the caller to modify the 35 * arrays returned by accessors for array-valued enum members; it will 36 * have no affect on the arrays returned to other callers. 37 * 38 * <p>An annotation A is <em>directly present</em> on an element E if the 39 * RuntimeVisibleAnnotations or RuntimeVisibleParameterAnnotations attribute 40 * associated with E either: 41 * <ul> 42 * <li>contains A; or 43 * <li>for invocations of get[Declared]Annotations(Class<T>), 44 * contains A or exactly one annotation C whose type is the containing 45 * annotation type of A's type (JLS 9.6) and whose value element contains A 46 * </ul> 47 * 48 * <p>An annotation A is <em>present</em> on an element E if either: 49 * <ul> 50 * <li>A is <em>directly present</em> on E; or 51 * <li>There are no annotations of A's type which are <em>directly present</em> 52 * on E, and E is a class, and A's type is inheritable (JLS 9.6.3.3), and A is 53 * present on the superclass of E 54 * </ul> 55 * 56 * <p>If an annotation returned by a method in this interface contains 57 * (directly or indirectly) a {@link Class}-valued member referring to 58 * a class that is not accessible in this VM, attempting to read the class 59 * by calling the relevant Class-returning method on the returned annotation 60 * will result in a {@link TypeNotPresentException}. 61 * 62 * <p>Similarly, attempting to read an enum-valued member will result in 63 * a {@link EnumConstantNotPresentException} if the enum constant in the 64 * annotation is no longer present in the enum type. 65 * 66 * <p>Attempting to read annotations of a repeatable annotation type T 67 * that are contained in an annotation whose type is not, in fact, the 68 * containing annotation type of T will result in an 69 * InvalidContainerAnnotationError. 70 * 71 * <p>Finally, attempting to read a member whose definition has evolved 72 * incompatibly will result in a {@link 73 * java.lang.annotation.AnnotationTypeMismatchException} or an 74 * {@link java.lang.annotation.IncompleteAnnotationException}. 75 * 76 * @see java.lang.EnumConstantNotPresentException 77 * @see java.lang.TypeNotPresentException 78 * @see java.lang.annotation.AnnotationFormatError 79 * @see java.lang.annotation.AnnotationTypeMismatchException 80 * @see java.lang.annotation.IncompleteAnnotationException 81 * @see java.lang.annotation.InvalidContainerAnnotationError 82 * @since 1.5 83 * @author Josh Bloch 84 */ 85 public interface AnnotatedElement { 86 /** 87 * Returns true if an annotation for the specified type 88 * is present on this element, else false. This method 89 * is designed primarily for convenient access to marker annotations. 90 * 91 * <p>The truth value returned by this method is equivalent to: 92 * {@code getAnnotation(annotationClass) != null} 93 * 94 * <p>The body of default method is specified to be the code 95 * above. 96 * 97 * @param annotationClass the Class object corresponding to the 98 * annotation type 99 * @return true if an annotation for the specified annotation 100 * type is present on this element, else false 101 * @throws NullPointerException if the given annotation class is null 102 * @since 1.5 103 */ 104 default boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) { 105 return getAnnotation(annotationClass) != null; 106 } 107 108 /** 109 * Returns this element's annotation for the specified type if 110 * such an annotation is present, else null. 111 * 112 * @param annotationClass the Class object corresponding to the 113 * annotation type 114 * @return this element's annotation for the specified annotation type if 115 * present on this element, else null 116 * @throws NullPointerException if the given annotation class is null 117 * @since 1.5 118 */ 119 <T extends Annotation> T getAnnotation(Class<T> annotationClass); 120 121 /** 122 * Returns an array of all this element's annotations for the 123 * specified type if one or more of such annotation is present, 124 * else an array of length zero. 125 * 126 * The caller of this method is free to modify the returned array; 127 * it will have no effect on the arrays returned to other callers. 128 * 129 * @param annotationClass the Class object corresponding to the 130 * annotation type 131 * @return all this element's annotations for the specified annotation type if 132 * present on this element, else an array of length zero 133 * @throws NullPointerException if the given annotation class is null 134 * @since 1.8 135 */ 136 <T extends Annotation> T[] getAnnotations(Class<T> annotationClass); 137 138 /** 139 * Returns annotations that are <em>present</em> on this element. 140 * 141 * If there are no annotations <em>present</em> on this element, the return 142 * value is an array of length 0. 143 * 144 * The caller of this method is free to modify the returned array; it will 145 * have no effect on the arrays returned to other callers. 146 * 147 * @return annotations present on this element 148 * @since 1.5 149 */ 150 Annotation[] getAnnotations(); 151 152 /** 153 * Returns this element's annotation for the specified type if 154 * such an annotation is present, else null. 155 * 156 * This method ignores inherited annotations. (Returns null if no 157 * annotations are directly present on this element.) 158 * 159 * @param annotationClass the Class object corresponding to the 160 * annotation type 161 * @return this element's annotation for the specified annotation type if 162 * present on this element, else null 163 * @throws NullPointerException if the given annotation class is null 164 * @since 1.8 165 */ 166 <T extends Annotation> T getDeclaredAnnotation(Class<T> annotationClass); 167 168 /** 169 * Returns an array of all this element's annotations for the 170 * specified type if one or more of such annotation is directly 171 * present, else an array of length zero. 172 * 173 * This method ignores inherited annotations. (Returns 174 * an array of length zero if no annotations are directly present 175 * on this element.) The caller of this method is free to modify 176 * the returned array; it will have no effect on the arrays 177 * returned to other callers. 178 * 179 * @param annotationClass the Class object corresponding to the 180 * annotation type 181 * @return all this element's annotations for the specified annotation type if 182 * present on this element, else an array of length zero 183 * @throws NullPointerException if the given annotation class is null 184 * @since 1.8 185 */ 186 <T extends Annotation> T[] getDeclaredAnnotations(Class<T> annotationClass); 187 188 /** 189 * Returns annotations that are <em>directly present</em> on this element. 190 * This method ignores inherited annotations. 191 * 192 * If there are no annotations <em>directly present</em> on this element, 193 * the return value is an array of length 0. 194 * 195 * The caller of this method is free to modify the returned array; it will 196 * have no effect on the arrays returned to other callers. 197 * 198 * @return annotations directly present on this element 199 * @since 1.5 200 */ 201 Annotation[] getDeclaredAnnotations(); 202 }