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 * @param annotationClass the Class object corresponding to the
95 * annotation type
96 * @return true if an annotation for the specified annotation
97 * type is present on this element, else false
98 * @throws NullPointerException if the given annotation class is null
99 * @since 1.5
100 */
101 boolean isAnnotationPresent(Class<? extends Annotation> annotationClass);
102
103 /**
104 * Returns this element's annotation for the specified type if
105 * such an annotation is present, else null.
106 *
107 * @param annotationClass the Class object corresponding to the
108 * annotation type
109 * @return this element's annotation for the specified annotation type if
110 * present on this element, else null
111 * @throws NullPointerException if the given annotation class is null
112 * @since 1.5
113 */
114 <T extends Annotation> T getAnnotation(Class<T> annotationClass);
115
116 /**
117 * Returns an array of all this element's annotations for the
118 * specified type if one or more of such annotation is present,
119 * else an array of length zero.
120 *
121 * The caller of this method is free to modify the returned array;
122 * it will have no effect on the arrays returned to other callers.
123 *
124 * @param annotationClass the Class object corresponding to the
125 * annotation type
126 * @return all this element's annotations for the specified annotation type if
127 * present on this element, else an array of length zero
128 * @throws NullPointerException if the given annotation class is null
129 * @since 1.8
130 */
131 <T extends Annotation> T[] getAnnotations(Class<T> annotationClass);
132
133 /**
134 * Returns annotations that are <em>present</em> on this element.
135 *
136 * If there are no annotations <em>present</em> on this element, the return
137 * value is an array of length 0.
138 *
139 * The caller of this method is free to modify the returned array; it will
140 * have no effect on the arrays returned to other callers.
141 *
142 * @return annotations present on this element
143 * @since 1.5
144 */
145 Annotation[] getAnnotations();
146
147 /**
148 * Returns this element's annotation for the specified type if
149 * such an annotation is present, else null.
150 *
151 * This method ignores inherited annotations. (Returns null if no
152 * annotations are directly present on this element.)
153 *
154 * @param annotationClass the Class object corresponding to the
155 * annotation type
156 * @return this element's annotation for the specified annotation type if
157 * present on this element, else null
158 * @throws NullPointerException if the given annotation class is null
159 * @since 1.8
160 */
161 <T extends Annotation> T getDeclaredAnnotation(Class<T> annotationClass);
162
163 /**
164 * Returns an array of all this element's annotations for the
165 * specified type if one or more of such annotation is directly
166 * present, else an array of length zero.
167 *
168 * This method ignores inherited annotations. (Returns
169 * an array of length zero if no annotations are directly present
170 * on this element.) The caller of this method is free to modify
171 * the returned array; it will have no effect on the arrays
172 * returned to other callers.
173 *
174 * @param annotationClass the Class object corresponding to the
175 * annotation type
176 * @return all this element's annotations for the specified annotation type if
177 * present on this element, else an array of length zero
178 * @throws NullPointerException if the given annotation class is null
179 * @since 1.8
180 */
181 <T extends Annotation> T[] getDeclaredAnnotations(Class<T> annotationClass);
182
183 /**
184 * Returns annotations that are <em>directly present</em> on this element.
185 * This method ignores inherited annotations.
186 *
187 * If there are no annotations <em>directly present</em> on this element,
188 * the return value is an array of length 0.
189 *
190 * The caller of this method is free to modify the returned array; it will
191 * have no effect on the arrays returned to other callers.
192 *
193 * @return annotations directly present on this element
194 * @since 1.5
195 */
196 Annotation[] getDeclaredAnnotations();
197 }