1 /*
2 * Copyright (c) 2005, 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
23 * questions.
24 */
25
26 package javax.lang.model.element;
27
28
29 import java.lang.annotation.Annotation;
30 import java.lang.annotation.AnnotationTypeMismatchException;
31 import java.lang.annotation.IncompleteAnnotationException;
32 import java.util.List;
33 import java.util.Set;
34
35 import javax.lang.model.type.*;
36 import javax.lang.model.util.*;
37
38
39 /**
40 * Represents a program element such as a module, package, class, or method.
41 * Each element represents a static, language-level construct
42 * (and not, for example, a runtime construct of the virtual machine).
43 *
44 * <p> Elements should be compared using the {@link #equals(Object)}
45 * method. There is no guarantee that any particular element will
46 * always be represented by the same object.
47 *
48 * <p> To implement operations based on the class of an {@code
49 * Element} object, either use a {@linkplain ElementVisitor visitor} or
50 * use the result of the {@link #getKind} method. Using {@code
51 * instanceof} is <em>not</em> necessarily a reliable idiom for
52 * determining the effective class of an object in this modeling
53 * hierarchy since an implementation may choose to have a single object
54 * implement multiple {@code Element} subinterfaces.
55 *
56 * @author Joseph D. Darcy
57 * @author Scott Seligman
58 * @author Peter von der Ahé
59 * @see Elements
60 * @see TypeMirror
61 * @since 1.6
62 */
63 public interface Element extends javax.lang.model.AnnotatedConstruct {
64 /**
65 * Returns the type defined by this element.
66 * @return the type defined by this element
67 *
68 * @see Types
69 * @see ExecutableElement#asType
70 * @see ModuleElement#asType
71 * @see PackageElement#asType
72 * @see TypeElement#asType
73 * @see TypeParameterElement#asType
74 * @see VariableElement#asType
75 */
76 TypeMirror asType();
77
78 /**
79 * Returns the {@code kind} of this element.
80 *
81 * <ul>
82 *
83 * <li> The kind of a {@linkplain PackageElement package} is
84 * {@link ElementKind#PACKAGE PACKAGE}.
85 *
86 * <li> The kind of a {@linkplain ModuleElement module} is {@link
87 * ElementKind#MODULE MODULE}.
88 *
89 * <li> The kind of a {@linkplain TypeElement type element} is one
90 * of {@link ElementKind#ANNOTATION_TYPE ANNOTATION_TYPE}, {@link
91 * ElementKind#CLASS CLASS}, {@link ElementKind#ENUM ENUM}, {@link
92 * ElementKind#INTERFACE INTERFACE}, or {@link ElementKind#RECORD
93 * RECORD}.
94 *
95 * <li> The kind of a {@linkplain VariableElement variable} is one
96 * of {@link ElementKind#ENUM_CONSTANT ENUM_CONSTANT}, {@link
97 * ElementKind#EXCEPTION_PARAMETER EXCEPTION_PARAMETER}, {@link
98 * ElementKind#FIELD FIELD}, {@link ElementKind#LOCAL_VARIABLE
99 * LOCAL_VARIABLE}, {@link ElementKind#PARAMETER PARAMETER},
100 * {@link ElementKind#RESOURCE_VARIABLE RESOURCE_VARIABLE}, or
101 * {@link ElementKind#BINDING_VARIABLE BINDING_VARIABLE}.
102 *
103 * <li> The kind of an {@linkplain ExecutableElement executable}
104 * is one of {@link ElementKind#CONSTRUCTOR CONSTRUCTOR}, {@link
105 * ElementKind#INSTANCE_INIT INSTANCE_INIT}, {@link
106 * ElementKind#METHOD METHOD}, or {@link ElementKind#STATIC_INIT
107 * STATIC_INIT}.
108 *
109 * <li> The kind of a {@linkplain TypeParameterElement type parameter} is
110 * {@link ElementKind#TYPE_PARAMETER TYPE_PARAMETER}.
111 *
112 * <li> The kind of a {@linkplain RecordComponentElement record
113 * component} is {@link ElementKind#RECORD_COMPONENT
114 * RECORD_COMPONENT}.
115 *
116 * </ul>
117 *
118 * @return the kind of this element
119 */
120 ElementKind getKind();
121
122 /**
123 * Returns the modifiers of this element, excluding annotations.
124 * Implicit modifiers, such as the {@code public} and {@code static}
125 * modifiers of interface members, are included.
126 *
127 * @return the modifiers of this element, or an empty set if there are none
128 */
129 Set<Modifier> getModifiers();
130
131 /**
132 * Returns the simple (unqualified) name of this element. The
133 * name of a generic type does not include any reference to its
134 * formal type parameters.
135 *
136 * For example, the simple name of the type element {@code
137 * java.util.Set<E>} is {@code "Set"}.
138 *
139 * If this element represents an unnamed {@linkplain
140 * PackageElement#getSimpleName package} or unnamed {@linkplain
141 * ModuleElement#getSimpleName module}, an empty name is returned.
142 *
143 * If it represents a {@linkplain ExecutableElement#getSimpleName
144 * constructor}, the name "{@code <init>}" is returned. If it
145 * represents a {@linkplain ExecutableElement#getSimpleName static
146 * initializer}, the name "{@code <clinit>}" is returned.
147 *
148 * If it represents an {@linkplain TypeElement#getSimpleName
149 * anonymous class} or {@linkplain ExecutableElement#getSimpleName
150 * instance initializer}, an empty name is returned.
151 *
152 * @return the simple name of this element
153 * @see PackageElement#getSimpleName
154 * @see ExecutableElement#getSimpleName
155 * @see TypeElement#getSimpleName
156 * @see VariableElement#getSimpleName
157 * @see ModuleElement#getSimpleName
158 * @see RecordComponentElement#getSimpleName
159 * @revised 9
160 * @spec JPMS
161 */
162 Name getSimpleName();
163
164 /**
165 * Returns the innermost element
166 * within which this element is, loosely speaking, enclosed.
167 * <ul>
168 * <li> If this element is one whose declaration is lexically enclosed
169 * immediately within the declaration of another element, that other
170 * element is returned.
171 *
172 * <li> If this is a {@linkplain TypeElement#getEnclosingElement
173 * top-level type}, its package is returned.
174 *
175 * <li> If this is a {@linkplain
176 * PackageElement#getEnclosingElement package}, its module is
177 * returned if such a module exists. Otherwise, {@code null} is returned.
178 *
179 * <li> If this is a {@linkplain
180 * TypeParameterElement#getEnclosingElement type parameter},
181 * {@linkplain TypeParameterElement#getGenericElement the
182 * generic element} of the type parameter is returned.
183 *
184 * <li> If this is a {@linkplain
185 * VariableElement#getEnclosingElement method or constructor
186 * parameter}, {@linkplain ExecutableElement the executable
187 * element} which declares the parameter is returned.
188 *
189 * <li> If this is a {@linkplain
190 * RecordComponentElement#getEnclosingElement record component},
191 * {@linkplain TypeElement the type} which declares the
192 * record component is returned.
193 *
194 * <li> If this is a {@linkplain ModuleElement#getEnclosingElement
195 * module}, {@code null} is returned.
196 *
197 * </ul>
198 *
199 * @return the enclosing element, or {@code null} if there is none
200 * @see Elements#getPackageOf
201 * @revised 9
202 * @spec JPMS
203 */
204 Element getEnclosingElement();
205
206 /**
207 * Returns the elements that are, loosely speaking, directly
208 * enclosed by this element.
209 *
210 * A {@linkplain TypeElement#getEnclosedElements class or
211 * interface} is considered to enclose the fields, methods,
212 * constructors, record components, and member types that it directly declares.
213 *
214 * A {@linkplain PackageElement#getEnclosedElements package}
215 * encloses the top-level classes and interfaces within it, but is
216 * not considered to enclose subpackages.
217 *
218 * A {@linkplain ModuleElement#getEnclosedElements module}
219 * encloses packages within it.
220 *
221 * Enclosed elements may include implicitly declared {@linkplain
222 * Elements.Origin#MANDATED mandated} elements.
223 *
224 * Other kinds of elements are not currently considered to enclose
225 * any elements; however, that may change as this API or the
226 * programming language evolves.
227 *
228 * @apiNote Elements of certain kinds can be isolated using
229 * methods in {@link ElementFilter}.
230 *
231 * @return the enclosed elements, or an empty list if none
232 * @see TypeElement#getEnclosedElements
233 * @see PackageElement#getEnclosedElements
234 * @see ModuleElement#getEnclosedElements
235 * @see Elements#getAllMembers
236 * @jls 8.8.9 Default Constructor
237 * @jls 8.9 Enum Types
238 * @revised 9
239 * @spec JPMS
240 */
241 List<? extends Element> getEnclosedElements();
242
243 /**
244 * Returns {@code true} if the argument represents the same
245 * element as {@code this}, or {@code false} otherwise.
246 *
247 * @apiNote The identity of an element involves implicit state
248 * not directly accessible from the element's methods, including
249 * state about the presence of unrelated types. Element objects
250 * created by different implementations of these interfaces should
251 * <i>not</i> be expected to be equal even if "the same"
252 * element is being modeled; this is analogous to the inequality
253 * of {@code Class} objects for the same class file loaded through
254 * different class loaders.
255 *
256 * @param obj the object to be compared with this element
257 * @return {@code true} if the specified object represents the same
258 * element as this
259 */
260 @Override
261 boolean equals(Object obj);
262
263 /**
264 * Obeys the general contract of {@link Object#hashCode Object.hashCode}.
265 *
266 * @see #equals
267 */
268 @Override
269 int hashCode();
270
271
272 /**
273 * {@inheritDoc}
274 *
275 * <p> To get inherited annotations as well, use {@link
276 * Elements#getAllAnnotationMirrors(Element)
277 * getAllAnnotationMirrors}.
278 *
279 * @since 1.6
280 */
281 @Override
282 List<? extends AnnotationMirror> getAnnotationMirrors();
283
284 /**
285 * {@inheritDoc}
286 * @since 1.6
287 */
288 @Override
289 <A extends Annotation> A getAnnotation(Class<A> annotationType);
290
291 /**
292 * Applies a visitor to this element.
293 *
294 * @param <R> the return type of the visitor's methods
295 * @param <P> the type of the additional parameter to the visitor's methods
296 * @param v the visitor operating on this element
297 * @param p additional parameter to the visitor
298 * @return a visitor-specified result
299 */
300 <R, P> R accept(ElementVisitor<R, P> v, P p);
301 }