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 import java.lang.annotation.AnnotationFormatError; 30 31 /** 32 * Represents an annotated element of the program currently running in this 33 * VM. This interface allows annotations to be read reflectively. All 34 * annotations returned by methods in this interface are immutable and 35 * serializable. It is permissible for the caller to modify the 36 * arrays returned by accessors for array-valued enum members; it will 37 * have no affect on the arrays returned to other callers. 38 * 39 * <p>The {@link #getAnnotationsByType(Class)} and {@link 40 * #getDeclaredAnnotationsByType(Class)} methods support multiple 41 * annotations of the same type on an element. If the argument to either method 42 * is a repeatable annotation type (JLS 9.6), then the method will "look 43 * through" a container annotation (JLS 9.7) which was generated at 44 * compile-time to wrap multiple annotations of the argument type. 45 * 46 * <p>The terms <em>directly present</em> and <em>present</em> are used 47 * throughout this interface to describe precisely which annotations are 48 * returned by methods: 49 * 50 * <ul> 51 * <li>An annotation A is <em>directly present</em> on an element E if E is 52 * associated with a RuntimeVisibleAnnotations or 53 * RuntimeVisibleParameterAnnotations attribute, and: 54 * 55 * <ul> 56 * <li>for an invocation of {@code get[Declared]Annotation(Class<T>)} or 57 * {@code get[Declared]Annotations()}, the attribute contains A. 58 * 59 * <li>for an invocation of {@code get[Declared]AnnotationsByType(Class<T>)}, the 60 * attribute either contains A or, if the type of A is repeatable, contains 61 * exactly one annotation whose value element contains A and whose type is the 62 * containing annotation type of A's type (JLS 9.6). 63 * </ul> 64 * 65 * <p> 66 * <li>An annotation A is <em>present</em> on an element E if either: 67 * 68 * <ul> 69 * <li>A is <em>directly present</em> on E; or 70 * 71 * <li>A is not <em>directly present</em> on E, and E is a class, and A's type 72 * is inheritable (JLS 9.6.3.3), and A is <em>present</em> on the superclass of 73 * E. 74 * </ul> 75 * 76 * </ul> 77 * 78 * <p>If an annotation returned by a method in this interface contains 79 * (directly or indirectly) a {@link Class}-valued member referring to 80 * a class that is not accessible in this VM, attempting to read the class 81 * by calling the relevant Class-returning method on the returned annotation 82 * will result in a {@link TypeNotPresentException}. 83 * 84 * <p>Similarly, attempting to read an enum-valued member will result in 85 * a {@link EnumConstantNotPresentException} if the enum constant in the 86 * annotation is no longer present in the enum type. 87 * 88 * <p>Attempting to read annotations of a repeatable annotation type T 89 * that are contained in an annotation whose type is not, in fact, the 90 * containing annotation type of T, will result in an {@link 91 * AnnotationFormatError}. 92 * 93 * <p>Finally, attempting to read a member whose definition has evolved 94 * incompatibly will result in a {@link 95 * java.lang.annotation.AnnotationTypeMismatchException} or an 96 * {@link java.lang.annotation.IncompleteAnnotationException}. 97 * 98 * @see java.lang.EnumConstantNotPresentException 99 * @see java.lang.TypeNotPresentException 100 * @see AnnotationFormatError 101 * @see java.lang.annotation.AnnotationTypeMismatchException 102 * @see java.lang.annotation.IncompleteAnnotationException 103 * @since 1.5 104 * @author Josh Bloch 105 */ 106 public interface AnnotatedElement { 107 /** 108 * Returns true if an annotation for the specified type 109 * is present on this element, else false. This method 110 * is designed primarily for convenient access to marker annotations. 111 * 112 * <p>The truth value returned by this method is equivalent to: 113 * {@code getAnnotation(annotationClass) != null} 114 * 115 * <p>The body of the default method is specified to be the code 116 * above. 117 * 118 * @param annotationClass the Class object corresponding to the 119 * annotation type 120 * @return true if an annotation for the specified annotation 121 * type is present on this element, else false 122 * @throws NullPointerException if the given annotation class is null 123 * @since 1.5 124 */ 125 default boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) { 126 return getAnnotation(annotationClass) != null; 127 } 128 129 /** 130 * Returns this element's annotation for the specified type if 131 * such an annotation is present, else null. 132 * 133 * @param <T> the type of the annotation to query for and return if present 134 * @param annotationClass the Class object corresponding to the 135 * annotation type 136 * @return this element's annotation for the specified annotation type if 137 * present on this element, else null 138 * @throws NullPointerException if the given annotation class is null 139 * @since 1.5 140 */ 141 <T extends Annotation> T getAnnotation(Class<T> annotationClass); 142 143 /** 144 * Returns annotations that are <em>present</em> on this element. 145 * 146 * If there are no annotations <em>present</em> on this element, the return 147 * value is an array of length 0. 148 * 149 * The difference between this method and {@link #getAnnotation(Class)} 150 * is that this method detects if its argument is a <em>repeatable 151 * annotation type</em> (JLS 9.6), and if so, attempts to find one or 152 * more annotations of that type by "looking through" a container 153 * annotation. 154 * 155 * The caller of this method is free to modify the returned array; it will 156 * have no effect on the arrays returned to other callers. 157 * 158 * @param <T> the type of the annotation to query for and return if present 159 * @param annotationClass the Class object corresponding to the 160 * annotation type 161 * @return all this element's annotations for the specified annotation type if 162 * present on this element, else an array of length zero 163 * @throws NullPointerException if the given annotation class is null 164 * @since 1.8 165 */ 166 <T extends Annotation> T[] getAnnotationsByType(Class<T> annotationClass); 167 168 /** 169 * Returns annotations that are <em>present</em> on this element. 170 * 171 * If there are no annotations <em>present</em> on this element, the return 172 * value is an array of length 0. 173 * 174 * The caller of this method is free to modify the returned array; it will 175 * have no effect on the arrays returned to other callers. 176 * 177 * @return annotations present on this element 178 * @since 1.5 179 */ 180 Annotation[] getAnnotations(); 181 182 /** 183 * Returns this element's annotation for the specified type if 184 * such an annotation is present, else null. 185 * 186 * This method ignores inherited annotations. (Returns null if no 187 * annotations are directly present on this element.) 188 * 189 * @param <T> the type of the annotation to query for and return if present 190 * @param annotationClass the Class object corresponding to the 191 * annotation type 192 * @return this element's annotation for the specified annotation type if 193 * present on this element, else null 194 * @throws NullPointerException if the given annotation class is null 195 * @since 1.8 196 */ 197 <T extends Annotation> T getDeclaredAnnotation(Class<T> annotationClass); 198 199 /** 200 * Returns annotations that are <em>directly present</em> on this element. 201 * This method ignores inherited annotations. 202 * 203 * If there are no annotations <em>directly present</em> on this element, 204 * the return value is an array of length 0. 205 * 206 * The difference between this method and {@link 207 * #getDeclaredAnnotation(Class)} is that this method detects if its 208 * argument is a <em>repeatable annotation type</em> (JLS 9.6), and if so, 209 * attempts to find one or more annotations of that type by "looking 210 * through" a container annotation. 211 * 212 * The caller of this method is free to modify the returned array; it will 213 * have no effect on the arrays returned to other callers. 214 * 215 * @param <T> the type of the annotation to query for and return 216 * if directly present 217 * @param annotationClass the Class object corresponding to the 218 * annotation type 219 * @return all this element's annotations for the specified annotation type if 220 * present on this element, else an array of length zero 221 * @throws NullPointerException if the given annotation class is null 222 * @since 1.8 223 */ 224 <T extends Annotation> T[] getDeclaredAnnotationsByType(Class<T> annotationClass); 225 226 /** 227 * Returns annotations that are <em>directly present</em> on this element. 228 * This method ignores inherited annotations. 229 * 230 * If there are no annotations <em>directly present</em> on this element, 231 * the return value is an array of length 0. 232 * 233 * The caller of this method is free to modify the returned array; it will 234 * have no effect on the arrays returned to other callers. 235 * 236 * @return annotations directly present on this element 237 * @since 1.5 238 */ 239 Annotation[] getDeclaredAnnotations(); 240 } | 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 import java.lang.annotation.AnnotationFormatError; 30 31 /** 32 * Represents an annotated element of the program currently running in this 33 * VM. This interface allows annotations to be read reflectively. All 34 * annotations returned by methods in this interface are immutable and 35 * serializable. The arrays returned by methods of this interface may be modified 36 * by callers without affecting the arrays returned to other callers. 37 * 38 * <p>The {@link #getAnnotationsByType(Class)} and {@link 39 * #getDeclaredAnnotationsByType(Class)} methods support multiple 40 * annotations of the same type on an element. If the argument to 41 * either method is a repeatable annotation type (JLS 9.6), then the 42 * method will "look through" a container annotation (JLS 9.7) and 43 * return the one or more annotations inside the container. Container 44 * annotations may be generated at compile-time to wrap multiple 45 * annotations of the argument type. 46 * 47 * <p>The terms <em>directly present</em>, <em>indirectly present</em>, 48 * <em>present</em>, and <em>associated</em> are used throughout this 49 * interface to describe precisely which annotations are returned by 50 * methods: 51 * 52 * <ul> 53 * 54 * <li> An annotation <i>A</i> is <em>directly present</em> on an 55 * element <i>E</i> if <i>E</i> has a {@code 56 * RuntimeVisibleAnnotations} or {@code 57 * RuntimeVisibleParameterAnnotations} or {@code 58 * RuntimeVisibleTypeAnnotations} attribute, and the attribute 59 * contains <i>A</i>. 60 * 61 * <li>An annotation <i>A</i> is <em>indirectly present</em> on an 62 * element <i>E</i> if <i>E</i> has a {@code RuntimeVisibleAnnotations} or 63 * {@code RuntimeVisibleParameterAnnotations} or {@code RuntimeVisibleTypeAnnotations} 64 * attribute, and <i>A</i> 's type is repeatable, and the attribute contains 65 * exactly one annotation whose value element contains <i>A</i> and whose 66 * type is the containing annotation type of <i>A</i> 's type. 67 * 68 * <li>An annotation <i>A</i> is present on an element <i>E</i> if either: 69 * 70 * <ul> 71 * 72 * <li><i>A</i> is directly present on <i>E</i>; or 73 * 74 * <li>No annotation of <i>A</i> 's type is directly present on 75 * <i>E</i>, and <i>E</i> is a class, and <i>A</i> 's type is 76 * inheritable, and <i>A</i> is present on the superclass of <i>E</i>. 77 * 78 * </ul> 79 * 80 * <li>An annotation <i>A</i> is <em>associated</em> with an element <i>E</i> 81 * if either: 82 * 83 * <ul> 84 * 85 * <li><i>A</i> is directly or indirectly present on <i>E</i>; or 86 * 87 * <li>No annotation of <i>A</i> 's type is directly or indirectly 88 * present on <i>E</i>, and <i>E</i> is a class, and <i>A</i>'s type 89 * is inheritable, and <i>A</i> is associated with the superclass of 90 * <i>E</i>. 91 * 92 * </ul> 93 * 94 * </ul> 95 * 96 * For an invocation of {@code get[Declared]AnnotationsByType( Class < 97 * T >)}, the order of annotations which are directly or indirectly 98 * present on an element <i>E</i> is computed as if indirectly present 99 * annotations on <i>E</i> are directly present on <i>E</i> in place 100 * of their container annotation, in the order in which they appear in 101 * the value element of the container annotation. 102 103 * <p>If an annotation returned by a method in this interface contains 104 * (directly or indirectly) a {@link Class}-valued member referring to 105 * a class that is not accessible in this VM, attempting to read the class 106 * by calling the relevant Class-returning method on the returned annotation 107 * will result in a {@link TypeNotPresentException}. 108 * 109 * <p>Similarly, attempting to read an enum-valued member will result in 110 * a {@link EnumConstantNotPresentException} if the enum constant in the 111 * annotation is no longer present in the enum type. 112 * 113 * <p>If an annotation type <i>T</i> is (meta-)annotated with an 114 * {@code @Repeatable} annotation whose value element indicates a type 115 * <i>TC</i>, but <i>TC</i> does not declare a {@code value()} method 116 * with a return type of <i>T</i>{@code []}, then an exception of type 117 * {@link java.lang.annotation.AnnotationFormatError} is thrown. 118 * 119 * <p>Finally, attempting to read a member whose definition has evolved 120 * incompatibly will result in a {@link 121 * java.lang.annotation.AnnotationTypeMismatchException} or an 122 * {@link java.lang.annotation.IncompleteAnnotationException}. 123 * 124 * @see java.lang.EnumConstantNotPresentException 125 * @see java.lang.TypeNotPresentException 126 * @see AnnotationFormatError 127 * @see java.lang.annotation.AnnotationTypeMismatchException 128 * @see java.lang.annotation.IncompleteAnnotationException 129 * @since 1.5 130 * @author Josh Bloch 131 */ 132 public interface AnnotatedElement { 133 /** 134 * Returns true if an annotation for the specified type 135 * is <em>present</em> on this element, else false. This method 136 * is designed primarily for convenient access to marker annotations. 137 * 138 * <p>The truth value returned by this method is equivalent to: 139 * {@code getAnnotation(annotationClass) != null} 140 * 141 * <p>The body of the default method is specified to be the code 142 * above. 143 * 144 * @param annotationClass the Class object corresponding to the 145 * annotation type 146 * @return true if an annotation for the specified annotation 147 * type is present on this element, else false 148 * @throws NullPointerException if the given annotation class is null 149 * @since 1.5 150 */ 151 default boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) { 152 return getAnnotation(annotationClass) != null; 153 } 154 155 /** 156 * Returns this element's annotation for the specified type if 157 * such an annotation is <em>present</em>, else null. 158 * 159 * @param <T> the type of the annotation to query for and return if present 160 * @param annotationClass the Class object corresponding to the 161 * annotation type 162 * @return this element's annotation for the specified annotation type if 163 * present on this element, else null 164 * @throws NullPointerException if the given annotation class is null 165 * @since 1.5 166 */ 167 <T extends Annotation> T getAnnotation(Class<T> annotationClass); 168 169 /** 170 * Returns annotations that are <em>associated</em> with this element. 171 * 172 * If there are no annotations <em>associated</em> with this element, the return 173 * value is an array of length 0. 174 * 175 * The difference between this method and {@link #getAnnotation(Class)} 176 * is that this method detects if its argument is a <em>repeatable 177 * annotation type</em> (JLS 9.6), and if so, attempts to find one or 178 * more annotations of that type by "looking through" a container 179 * annotation. 180 * 181 * The caller of this method is free to modify the returned array; it will 182 * have no effect on the arrays returned to other callers. 183 * 184 * @param <T> the type of the annotation to query for and return if present 185 * @param annotationClass the Class object corresponding to the 186 * annotation type 187 * @return all this element's annotations for the specified annotation type if 188 * associated with this element, else an array of length zero 189 * @throws NullPointerException if the given annotation class is null 190 * @since 1.8 191 */ 192 <T extends Annotation> T[] getAnnotationsByType(Class<T> annotationClass); 193 194 /** 195 * Returns annotations that are <em>present</em> on this element. 196 * 197 * If there are no annotations <em>present</em> on this element, the return 198 * value is an array of length 0. 199 * 200 * The caller of this method is free to modify the returned array; it will 201 * have no effect on the arrays returned to other callers. 202 * 203 * @return annotations present on this element 204 * @since 1.5 205 */ 206 Annotation[] getAnnotations(); 207 208 /** 209 * Returns this element's annotation for the specified type if 210 * such an annotation is <em>directly present</em>, else null. 211 * 212 * This method ignores inherited annotations. (Returns null if no 213 * annotations are directly present on this element.) 214 * 215 * @param <T> the type of the annotation to query for and return if directly present 216 * @param annotationClass the Class object corresponding to the 217 * annotation type 218 * @return this element's annotation for the specified annotation type if 219 * directly present on this element, else null 220 * @throws NullPointerException if the given annotation class is null 221 * @since 1.8 222 */ 223 <T extends Annotation> T getDeclaredAnnotation(Class<T> annotationClass); 224 225 /** 226 * Returns this element's annotation(s) for the specified type if 227 * such annotations are either <em>directly present</em> or 228 * <em>indirectly present</em>. This method ignores inherited 229 * annotations. 230 * 231 * If there are no specified annotations directly or indirectly 232 * present on this element, the return value is an array of length 233 * 0. 234 * 235 * The difference between this method and {@link 236 * #getDeclaredAnnotation(Class)} is that this method detects if its 237 * argument is a <em>repeatable annotation type</em> (JLS 9.6), and if so, 238 * attempts to find one or more annotations of that type by "looking 239 * through" a container annotation. 240 * 241 * The caller of this method is free to modify the returned array; it will 242 * have no effect on the arrays returned to other callers. 243 * 244 * @param <T> the type of the annotation to query for and return 245 * if directly or indirectly present 246 * @param annotationClass the Class object corresponding to the 247 * annotation type 248 * @return all this element's annotations for the specified annotation type if 249 * directly present on this element, else an array of length zero 250 * @throws NullPointerException if the given annotation class is null 251 * @since 1.8 252 */ 253 <T extends Annotation> T[] getDeclaredAnnotationsByType(Class<T> annotationClass); 254 255 /** 256 * Returns annotations that are <em>directly present</em> on this element. 257 * This method ignores inherited annotations. 258 * 259 * If there are no annotations <em>directly present</em> on this element, 260 * the return value is an array of length 0. 261 * 262 * The caller of this method is free to modify the returned array; it will 263 * have no effect on the arrays returned to other callers. 264 * 265 * @return annotations directly present on this element 266 * @since 1.5 267 */ 268 Annotation[] getDeclaredAnnotations(); 269 } |