1 /*
2 * Copyright (c) 2013, 2020, 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
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24 */
25
26 package javax.lang.model;
27
28 import java.lang.annotation.*;
29 import java.util.List;
30 import javax.lang.model.element.*;
31 import javax.lang.model.type.*;
32
33 /**
34 * Represents a construct that can be annotated.
35 *
36 * A construct is either an {@linkplain
37 * javax.lang.model.element.Element element} or a {@linkplain
38 * javax.lang.model.type.TypeMirror type}. Annotations on an element
39 * are on a <em>declaration</em>, whereas annotations on a type are on
40 * a specific <em>use</em> of a type name.
41 *
42 * The terms <em>directly present</em>, <em>present</em>,
43 * <em>indirectly present</em>, and <em>associated </em> are used
44 * throughout this interface to describe precisely which annotations
45 * are returned by the methods defined herein.
46 *
47 * <p>In the definitions below, an annotation <i>A</i> has an
48 * annotation type <i>AT</i>. If <i>AT</i> is a repeatable annotation
49 * type, the type of the containing annotation is <i>ATC</i>.
50 *
51 * <p>Annotation <i>A</i> is <em>directly present</em> on a construct
52 * <i>C</i> if either:
53 *
54 * <ul>
55 *
56 * <li><i>A</i> is explicitly or implicitly declared as applying to
57 * the source code representation of <i>C</i>.
58 *
59 * <p>Typically, if exactly one annotation of type <i>AT</i> appears in
60 * the source code of representation of <i>C</i>, then <i>A</i> is
61 * explicitly declared as applying to <i>C</i>.
62 *
63 * An annotation of type <i>AT</i> on a {@linkplain
64 * RecordComponentElement record component} can be implicitly propagated
65 * down to affiliated mandated members. Type annotations modifying the
66 * type of a record component can be also propagated to mandated
67 * members. Propagation of the annotations to mandated members is
68 * governed by rules given in the <cite>The Java™ Language
69 * Specification</cite>.
70 *
71 * If there are multiple annotations of type <i>AT</i> present on
72 * <i>C</i>, then if <i>AT</i> is repeatable annotation type, an
73 * annotation of type <i>ATC</i> is {@linkplain javax.lang.model.util.Elements#getOrigin(AnnotatedConstruct, AnnotationMirror) implicitly declared} on <i>C</i>.
74 * <li> A representation of <i>A</i> appears in the executable output
75 * for <i>C</i>, such as the {@code RuntimeVisibleAnnotations} or
76 * {@code RuntimeVisibleParameterAnnotations} attributes of a class
77 * file.
78 *
79 * </ul>
80 *
81 * <p>An annotation <i>A</i> is <em>present</em> on a
82 * construct <i>C</i> if either:
83 * <ul>
84 *
85 * <li><i>A</i> is directly present on <i>C</i>.
86 *
87 * <li>No annotation of type <i>AT</i> is directly present on
88 * <i>C</i>, and <i>C</i> is a class and <i>AT</i> is inheritable
89 * and <i>A</i> is present on the superclass of <i>C</i>.
90 *
91 * </ul>
92 *
93 * An annotation <i>A</i> is <em>indirectly present</em> on a construct
94 * <i>C</i> if both:
95 *
96 * <ul>
97 *
98 * <li><i>AT</i> is a repeatable annotation type with a containing
99 * annotation type <i>ATC</i>.
100 *
101 * <li>An annotation of type <i>ATC</i> is directly present on
102 * <i>C</i> and <i>A</i> is an annotation included in the result of
103 * calling the {@code value} method of the directly present annotation
104 * of type <i>ATC</i>.
105 *
106 * </ul>
107 *
108 * An annotation <i>A</i> is <em>associated</em> with a construct
109 * <i>C</i> if either:
110 *
111 * <ul>
112 *
113 * <li> <i>A</i> is directly or indirectly present on <i>C</i>.
114 *
115 * <li> No annotation of type <i>AT</i> is directly or indirectly
116 * present on <i>C</i>, and <i>C</i> is a class, and <i>AT</i> is
117 * inheritable, and <i>A</i> is associated with the superclass of
118 * <i>C</i>.
119 *
120 * </ul>
121 *
122 * @since 1.8
123 * @jls 9.6 Annotation Types
124 * @jls 9.6.4.3 {@code @Inherited}
125 */
126 public interface AnnotatedConstruct {
127 /**
128 * Returns the annotations that are <em>directly present</em> on
129 * this construct.
130 *
131 * @return the annotations <em>directly present</em> on this
132 * construct; an empty list if there are none
133 */
134 List<? extends AnnotationMirror> getAnnotationMirrors();
135
136 /**
137 * Returns this construct's annotation of the specified type if
138 * such an annotation is <em>present</em>, else {@code null}.
139 *
140 * <p> The annotation returned by this method could contain an element
141 * whose value is of type {@code Class}.
142 * This value cannot be returned directly: information necessary to
143 * locate and load a class (such as the class loader to use) is
144 * not available, and the class might not be loadable at all.
145 * Attempting to read a {@code Class} object by invoking the relevant
146 * method on the returned annotation
147 * will result in a {@link MirroredTypeException},
148 * from which the corresponding {@link TypeMirror} may be extracted.
149 * Similarly, attempting to read a {@code Class[]}-valued element
150 * will result in a {@link MirroredTypesException}.
151 *
152 * <blockquote>
153 * <i>Note:</i> This method is unlike others in this and related
154 * interfaces. It operates on runtime reflective information —
155 * representations of annotation types currently loaded into the
156 * VM — rather than on the representations defined by and used
157 * throughout these interfaces. Consequently, calling methods on
158 * the returned annotation object can throw many of the exceptions
159 * that can be thrown when calling methods on an annotation object
160 * returned by core reflection. This method is intended for
161 * callers that are written to operate on a known, fixed set of
162 * annotation types.
163 * </blockquote>
164 *
165 * @param <A> the annotation type
166 * @param annotationType the {@code Class} object corresponding to
167 * the annotation type
168 * @return this construct's annotation for the specified
169 * annotation type if present, else {@code null}
170 *
171 * @see #getAnnotationMirrors()
172 * @see java.lang.reflect.AnnotatedElement#getAnnotation
173 * @see EnumConstantNotPresentException
174 * @see AnnotationTypeMismatchException
175 * @see IncompleteAnnotationException
176 * @see MirroredTypeException
177 * @see MirroredTypesException
178 * @jls 9.6.1 Annotation Type Elements
179 */
180 <A extends Annotation> A getAnnotation(Class<A> annotationType);
181
182 /**
183 * Returns annotations that are <em>associated</em> with this construct.
184 *
185 * If there are no annotations associated with this construct, the
186 * return value is an array of length 0.
187 *
188 * The order of annotations which are directly or indirectly
189 * present on a construct <i>C</i> is computed as if indirectly present
190 * annotations on <i>C</i> are directly present on <i>C</i> in place of their
191 * container annotation, in the order in which they appear in the
192 * value element of the container annotation.
193 *
194 * The difference between this method and {@link #getAnnotation(Class)}
195 * is that this method detects if its argument is a <em>repeatable
196 * annotation type</em>, and if so, attempts to find one or more
197 * annotations of that type by "looking through" a container annotation.
198 *
199 * <p> The annotations returned by this method could contain an element
200 * whose value is of type {@code Class}.
201 * This value cannot be returned directly: information necessary to
202 * locate and load a class (such as the class loader to use) is
203 * not available, and the class might not be loadable at all.
204 * Attempting to read a {@code Class} object by invoking the relevant
205 * method on the returned annotation
206 * will result in a {@link MirroredTypeException},
207 * from which the corresponding {@link TypeMirror} may be extracted.
208 * Similarly, attempting to read a {@code Class[]}-valued element
209 * will result in a {@link MirroredTypesException}.
210 *
211 * <blockquote>
212 * <i>Note:</i> This method is unlike others in this and related
213 * interfaces. It operates on runtime reflective information —
214 * representations of annotation types currently loaded into the
215 * VM — rather than on the representations defined by and used
216 * throughout these interfaces. Consequently, calling methods on
217 * the returned annotation object can throw many of the exceptions
218 * that can be thrown when calling methods on an annotation object
219 * returned by core reflection. This method is intended for
220 * callers that are written to operate on a known, fixed set of
221 * annotation types.
222 * </blockquote>
223 *
224 * @param <A> the annotation type
225 * @param annotationType the {@code Class} object corresponding to
226 * the annotation type
227 * @return this construct's annotations for the specified annotation
228 * type if present on this construct, else an empty array
229 *
230 * @see #getAnnotationMirrors()
231 * @see #getAnnotation(Class)
232 * @see java.lang.reflect.AnnotatedElement#getAnnotationsByType(Class)
233 * @see EnumConstantNotPresentException
234 * @see AnnotationTypeMismatchException
235 * @see IncompleteAnnotationException
236 * @see MirroredTypeException
237 * @see MirroredTypesException
238 * @jls 9.6 Annotation Types
239 * @jls 9.6.1 Annotation Type Elements
240 */
241 <A extends Annotation> A[] getAnnotationsByType(Class<A> annotationType);
242 }