1 /*
2 * Copyright (c) 2005, 2019, 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 *
67 * @see Types
68 * @see ExecutableElement#asType
69 * @see ModuleElement#asType
70 * @see PackageElement#asType
71 * @see TypeElement#asType
72 * @see TypeParameterElement#asType
73 * @see VariableElement#asType
74 *
75 * @return the type defined by this element
76 */
77 TypeMirror asType();
78
79 /**
80 * Returns the {@code kind} of this element.
81 *
82 * @return the kind of this element
83 */
84 ElementKind getKind();
85
86 /**
87 * Returns the modifiers of this element, excluding annotations.
88 * Implicit modifiers, such as the {@code public} and {@code static}
89 * modifiers of interface members, are included.
90 *
91 * @return the modifiers of this element, or an empty set if there are none
92 */
93 Set<Modifier> getModifiers();
94
95 /**
96 * Returns the simple (unqualified) name of this element. The
97 * name of a generic type does not include any reference to its
98 * formal type parameters.
99 *
100 * For example, the simple name of the type element {@code
101 * java.util.Set<E>} is {@code "Set"}.
102 *
103 * If this element represents an unnamed {@linkplain
104 * PackageElement#getSimpleName package} or unnamed {@linkplain
105 * ModuleElement#getSimpleName module}, an empty name is returned.
106 *
107 * If it represents a {@linkplain ExecutableElement#getSimpleName
108 * constructor}, the name "{@code <init>}" is returned. If it
109 * represents a {@linkplain ExecutableElement#getSimpleName static
110 * initializer}, the name "{@code <clinit>}" is returned.
111 *
112 * If it represents an {@linkplain TypeElement#getSimpleName
113 * anonymous class} or {@linkplain ExecutableElement#getSimpleName
114 * instance initializer}, an empty name is returned.
115 *
116 * @return the simple name of this element
117 * @see PackageElement#getSimpleName
118 * @see ExecutableElement#getSimpleName
119 * @see TypeElement#getSimpleName
120 * @see VariableElement#getSimpleName
121 * @see ModuleElement#getSimpleName
122 * @revised 9
123 * @spec JPMS
124 */
125 Name getSimpleName();
126
127 /**
128 * Returns the innermost element
129 * within which this element is, loosely speaking, enclosed.
130 * <ul>
131 * <li> If this element is one whose declaration is lexically enclosed
132 * immediately within the declaration of another element, that other
133 * element is returned.
134 *
135 * <li> If this is a {@linkplain TypeElement#getEnclosingElement
136 * top-level type}, its package is returned.
137 *
138 * <li> If this is a {@linkplain
139 * PackageElement#getEnclosingElement package}, its module is
140 * returned if such a module exists. Otherwise, {@code null} is returned.
141 *
142 * <li> If this is a {@linkplain
143 * TypeParameterElement#getEnclosingElement type parameter},
144 * {@linkplain TypeParameterElement#getGenericElement the
145 * generic element} of the type parameter is returned.
146 *
147 * <li> If this is a {@linkplain
148 * VariableElement#getEnclosingElement method or constructor
149 * parameter}, {@linkplain ExecutableElement the executable
150 * element} which declares the parameter is returned.
151 *
152 * <li> If this is a {@linkplain ModuleElement#getEnclosingElement
153 * module}, {@code null} is returned.
154 *
155 * </ul>
156 *
157 * @return the enclosing element, or {@code null} if there is none
158 * @see Elements#getPackageOf
159 * @revised 9
160 * @spec JPMS
161 */
162 Element getEnclosingElement();
163
164 /**
165 * Returns the elements that are, loosely speaking, directly
166 * enclosed by this element.
167 *
168 * A {@linkplain TypeElement#getEnclosedElements class or
169 * interface} is considered to enclose the fields, methods,
170 * constructors, and member types that it directly declares.
171 *
172 * A {@linkplain PackageElement#getEnclosedElements package}
173 * encloses the top-level classes and interfaces within it, but is
174 * not considered to enclose subpackages.
175 *
176 * A {@linkplain ModuleElement#getEnclosedElements module}
177 * encloses packages within it.
178 *
179 * Enclosed elements may include implicitly declared {@linkplain
180 * Elements.Origin#MANDATED mandated} elements.
181 *
182 * Other kinds of elements are not currently considered to enclose
183 * any elements; however, that may change as this API or the
184 * programming language evolves.
185 *
186 * @apiNote Elements of certain kinds can be isolated using
187 * methods in {@link ElementFilter}.
188 *
189 * @return the enclosed elements, or an empty list if none
190 * @see TypeElement#getEnclosedElements
191 * @see PackageElement#getEnclosedElements
192 * @see ModuleElement#getEnclosedElements
193 * @see Elements#getAllMembers
194 * @jls 8.8.9 Default Constructor
195 * @jls 8.9 Enum Types
196 * @revised 9
197 * @spec JPMS
198 */
199 List<? extends Element> getEnclosedElements();
200
201 /**
202 * Returns {@code true} if the argument represents the same
203 * element as {@code this}, or {@code false} otherwise.
204 *
205 * @apiNote The identity of an element involves implicit state
206 * not directly accessible from the element's methods, including
207 * state about the presence of unrelated types. Element objects
208 * created by different implementations of these interfaces should
209 * <i>not</i> be expected to be equal even if "the same"
210 * element is being modeled; this is analogous to the inequality
211 * of {@code Class} objects for the same class file loaded through
212 * different class loaders.
213 *
214 * @param obj the object to be compared with this element
215 * @return {@code true} if the specified object represents the same
216 * element as this
217 */
218 @Override
219 boolean equals(Object obj);
220
221 /**
222 * Obeys the general contract of {@link Object#hashCode Object.hashCode}.
223 *
224 * @see #equals
225 */
226 @Override
227 int hashCode();
228
229
230 /**
231 * {@inheritDoc}
232 *
233 * <p> To get inherited annotations as well, use {@link
234 * Elements#getAllAnnotationMirrors(Element)
235 * getAllAnnotationMirrors}.
236 *
237 * @since 1.6
238 */
239 @Override
240 List<? extends AnnotationMirror> getAnnotationMirrors();
241
242 /**
243 * {@inheritDoc}
244 * @since 1.6
245 */
246 @Override
247 <A extends Annotation> A getAnnotation(Class<A> annotationType);
248
249 /**
250 * Applies a visitor to this element.
251 *
252 * @param <R> the return type of the visitor's methods
253 * @param <P> the type of the additional parameter to the visitor's methods
254 * @param v the visitor operating on this element
255 * @param p additional parameter to the visitor
256 * @return a visitor-specified result
257 */
258 <R, P> R accept(ElementVisitor<R, P> v, P p);
259 }