1 /*
2 * Copyright (c) 2005, 2017, 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 * <p> A generic element defines a family of types, not just one.
68 * If this is a generic element, a <i>prototypical</i> type is
69 * returned. This is the element's invocation on the
70 * type variables corresponding to its own formal type parameters.
71 * For example,
72 * for the generic class element {@code C<N extends Number>},
73 * the parameterized type {@code C<N>} is returned.
74 * The {@link Types} utility interface has more general methods
75 * for obtaining the full range of types defined by an element.
76 *
77 * @see Types
78 *
79 * @return the type defined by this element
80 */
81 TypeMirror asType();
82
83 /**
84 * Returns the {@code kind} of this element.
85 *
86 * @return the kind of this element
87 */
88 ElementKind getKind();
89
90 /**
91 * Returns the modifiers of this element, excluding annotations.
92 * Implicit modifiers, such as the {@code public} and {@code static}
93 * modifiers of interface members, are included.
94 *
95 * @return the modifiers of this element, or an empty set if there are none
96 */
97 Set<Modifier> getModifiers();
98
99 /**
100 * Returns the simple (unqualified) name of this element. The
101 * name of a generic type does not include any reference to its
102 * formal type parameters.
103 *
104 * For example, the simple name of the type element {@code
105 * java.util.Set<E>} is {@code "Set"}.
106 *
107 * If this element represents an unnamed {@linkplain
108 * PackageElement#getSimpleName package} or unnamed {@linkplain
109 * ModuleElement#getSimpleName module}, an empty name is returned.
110 *
111 * If it represents a {@linkplain ExecutableElement#getSimpleName
112 * constructor}, the name "{@code <init>}" is returned. If it
113 * represents a {@linkplain ExecutableElement#getSimpleName static
114 * initializer}, the name "{@code <clinit>}" is returned.
115 *
116 * If it represents an {@linkplain TypeElement#getSimpleName
117 * anonymous class} or {@linkplain ExecutableElement#getSimpleName
118 * instance initializer}, an empty name is returned.
119 *
120 * @return the simple name of this element
121 * @see PackageElement#getSimpleName
122 * @see ExecutableElement#getSimpleName
123 * @see TypeElement#getSimpleName
124 * @see VariableElement#getSimpleName
125 * @see ModuleElement#getSimpleName
126 * @revised 9
127 * @spec JPMS
128 */
129 Name getSimpleName();
130
131 /**
132 * Returns the innermost element
133 * within which this element is, loosely speaking, enclosed.
134 * <ul>
135 * <li> If this element is one whose declaration is lexically enclosed
136 * immediately within the declaration of another element, that other
137 * element is returned.
138 *
139 * <li> If this is a {@linkplain TypeElement#getEnclosingElement
140 * top-level type}, its package is returned.
141 *
142 * <li> If this is a {@linkplain
143 * PackageElement#getEnclosingElement package}, its module is
144 * returned if such a module exists. Otherwise, {@code null} is returned.
145 *
146 * <li> If this is a {@linkplain
147 * TypeParameterElement#getEnclosingElement type parameter},
148 * {@linkplain TypeParameterElement#getGenericElement the
149 * generic element} of the type parameter is returned.
150 *
151 * <li> If this is a {@linkplain
152 * VariableElement#getEnclosingElement method or constructor
153 * parameter}, {@linkplain ExecutableElement the executable
154 * element} which declares the parameter is returned.
155 *
156 * <li> If this is a {@linkplain ModuleElement#getEnclosingElement
157 * module}, {@code null} is returned.
158 *
159 * </ul>
160 *
161 * @return the enclosing element, or {@code null} if there is none
162 * @see Elements#getPackageOf
163 * @revised 9
164 * @spec JPMS
165 */
166 Element getEnclosingElement();
167
168 /**
169 * Returns the elements that are, loosely speaking, directly
170 * enclosed by this element.
171 *
172 * A {@linkplain TypeElement#getEnclosedElements class or
173 * interface} is considered to enclose the fields, methods,
174 * constructors, and member types that it directly declares.
175 *
176 * A {@linkplain PackageElement#getEnclosedElements package}
177 * encloses the top-level classes and interfaces within it, but is
178 * not considered to enclose subpackages.
179 *
180 * A {@linkplain ModuleElement#getEnclosedElements module}
181 * encloses packages within it.
182 *
183 * Enclosed elements may include implicitly declared {@linkplain
184 * Elements.Origin#MANDATED mandated} elements.
185 *
186 * Other kinds of elements are not currently considered to enclose
187 * any elements; however, that may change as this API or the
188 * programming language evolves.
189 *
190 * @apiNote Elements of certain kinds can be isolated using
191 * methods in {@link ElementFilter}.
192 *
193 * @return the enclosed elements, or an empty list if none
194 * @see TypeElement#getEnclosedElements
195 * @see PackageElement#getEnclosedElements
196 * @see ModuleElement#getEnclosedElements
197 * @see Elements#getAllMembers
198 * @jls 8.8.9 Default Constructor
199 * @jls 8.9 Enums
200 * @revised 9
201 * @spec JPMS
202 */
203 List<? extends Element> getEnclosedElements();
204
205 /**
206 * Returns {@code true} if the argument represents the same
207 * element as {@code this}, or {@code false} otherwise.
208 *
209 * @apiNote The identity of an element involves implicit state
210 * not directly accessible from the element's methods, including
211 * state about the presence of unrelated types. Element objects
212 * created by different implementations of these interfaces should
213 * <i>not</i> be expected to be equal even if "the same"
214 * element is being modeled; this is analogous to the inequality
215 * of {@code Class} objects for the same class file loaded through
216 * different class loaders.
217 *
218 * @param obj the object to be compared with this element
219 * @return {@code true} if the specified object represents the same
220 * element as this
221 */
222 @Override
223 boolean equals(Object obj);
224
225 /**
226 * Obeys the general contract of {@link Object#hashCode Object.hashCode}.
227 *
228 * @see #equals
229 */
230 @Override
231 int hashCode();
232
233
234 /**
235 * {@inheritDoc}
236 *
237 * <p> To get inherited annotations as well, use {@link
238 * Elements#getAllAnnotationMirrors(Element)
239 * getAllAnnotationMirrors}.
240 *
241 * @since 1.6
242 */
243 @Override
244 List<? extends AnnotationMirror> getAnnotationMirrors();
245
246 /**
247 * {@inheritDoc}
248 * @since 1.6
249 */
250 @Override
251 <A extends Annotation> A getAnnotation(Class<A> annotationType);
252
253 /**
254 * Applies a visitor to this element.
255 *
256 * @param <R> the return type of the visitor's methods
257 * @param <P> the type of the additional parameter to the visitor's methods
258 * @param v the visitor operating on this element
259 * @param p additional parameter to the visitor
260 * @return a visitor-specified result
261 */
262 <R, P> R accept(ElementVisitor<R, P> v, P p);
263 }