1 /*
2 * Copyright 1996-2008 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.lang.reflect;
27
28 import java.security.AccessController;
29 import sun.reflect.LangReflectAccess;
30 import sun.reflect.ReflectionFactory;
31
32 /**
33 * The Modifier class provides {@code static} methods and
34 * constants to decode class and member access modifiers. The sets of
35 * modifiers are represented as integers with distinct bit positions
36 * representing different modifiers. The values for the constants
37 * representing the modifiers are taken from <a
38 * href="http://java.sun.com/docs/books/vmspec/2nd-edition/html/VMSpecTOC.doc.html"><i>The
39 * Java</i><sup><small>TM</small></sup> <i>Virtual Machine Specification, Second
40 * edition</i></a> tables
41 * <a href="http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#75734">4.1</a>,
42 * <a href="http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#88358">4.4</a>,
43 * <a href="http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#75568">4.5</a>, and
44 * <a href="http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#88478">4.7</a>.
45 *
46 * @see Class#getModifiers()
47 * @see Member#getModifiers()
48 *
49 * @author Nakul Saraiya
50 * @author Kenneth Russell
51 */
52 public
53 class Modifier {
54
55 /*
56 * Bootstrapping protocol between java.lang and java.lang.reflect
57 * packages
58 */
59 static {
60 sun.reflect.ReflectionFactory factory =
61 AccessController.doPrivileged(
62 new ReflectionFactory.GetReflectionFactoryAction());
63 factory.setLangReflectAccess(new java.lang.reflect.ReflectAccess());
64 }
65
66 /**
67 * Return {@code true} if the integer argument includes the
68 * {@code public} modifier, {@code false} otherwise.
69 *
70 * @param mod a set of modifiers
71 * @return {@code true} if {@code mod} includes the
72 * {@code public} modifier; {@code false} otherwise.
73 */
74 public static boolean isPublic(int mod) {
75 return (mod & PUBLIC) != 0;
76 }
77
78 /**
79 * Return {@code true} if the integer argument includes the
80 * {@code private} modifier, {@code false} otherwise.
81 *
82 * @param mod a set of modifiers
83 * @return {@code true} if {@code mod} includes the
84 * {@code private} modifier; {@code false} otherwise.
85 */
86 public static boolean isPrivate(int mod) {
87 return (mod & PRIVATE) != 0;
88 }
89
90 /**
91 * Return {@code true} if the integer argument includes the
92 * {@code protected} modifier, {@code false} otherwise.
93 *
94 * @param mod a set of modifiers
95 * @return {@code true} if {@code mod} includes the
96 * {@code protected} modifier; {@code false} otherwise.
97 */
98 public static boolean isProtected(int mod) {
99 return (mod & PROTECTED) != 0;
100 }
101
102 /**
103 * Return {@code true} if the integer argument includes the
104 * {@code static} modifier, {@code false} otherwise.
105 *
106 * @param mod a set of modifiers
107 * @return {@code true} if {@code mod} includes the
108 * {@code static} modifier; {@code false} otherwise.
109 */
110 public static boolean isStatic(int mod) {
111 return (mod & STATIC) != 0;
112 }
113
114 /**
115 * Return {@code true} if the integer argument includes the
116 * {@code final} modifier, {@code false} otherwise.
117 *
118 * @param mod a set of modifiers
119 * @return {@code true} if {@code mod} includes the
120 * {@code final} modifier; {@code false} otherwise.
121 */
122 public static boolean isFinal(int mod) {
123 return (mod & FINAL) != 0;
124 }
125
126 /**
127 * Return {@code true} if the integer argument includes the
128 * {@code synchronized} modifier, {@code false} otherwise.
129 *
130 * @param mod a set of modifiers
131 * @return {@code true} if {@code mod} includes the
132 * {@code synchronized} modifier; {@code false} otherwise.
133 */
134 public static boolean isSynchronized(int mod) {
135 return (mod & SYNCHRONIZED) != 0;
136 }
137
138 /**
139 * Return {@code true} if the integer argument includes the
140 * {@code volatile} modifier, {@code false} otherwise.
141 *
142 * @param mod a set of modifiers
143 * @return {@code true} if {@code mod} includes the
144 * {@code volatile} modifier; {@code false} otherwise.
145 */
146 public static boolean isVolatile(int mod) {
147 return (mod & VOLATILE) != 0;
148 }
149
150 /**
151 * Return {@code true} if the integer argument includes the
152 * {@code transient} modifier, {@code false} otherwise.
153 *
154 * @param mod a set of modifiers
155 * @return {@code true} if {@code mod} includes the
156 * {@code transient} modifier; {@code false} otherwise.
157 */
158 public static boolean isTransient(int mod) {
159 return (mod & TRANSIENT) != 0;
160 }
161
162 /**
163 * Return {@code true} if the integer argument includes the
164 * {@code native} modifier, {@code false} otherwise.
165 *
166 * @param mod a set of modifiers
167 * @return {@code true} if {@code mod} includes the
168 * {@code native} modifier; {@code false} otherwise.
169 */
170 public static boolean isNative(int mod) {
171 return (mod & NATIVE) != 0;
172 }
173
174 /**
175 * Return {@code true} if the integer argument includes the
176 * {@code interface} modifier, {@code false} otherwise.
177 *
178 * @param mod a set of modifiers
179 * @return {@code true} if {@code mod} includes the
180 * {@code interface} modifier; {@code false} otherwise.
181 */
182 public static boolean isInterface(int mod) {
183 return (mod & INTERFACE) != 0;
184 }
185
186 /**
187 * Return {@code true} if the integer argument includes the
188 * {@code abstract} modifier, {@code false} otherwise.
189 *
190 * @param mod a set of modifiers
191 * @return {@code true} if {@code mod} includes the
192 * {@code abstract} modifier; {@code false} otherwise.
193 */
194 public static boolean isAbstract(int mod) {
195 return (mod & ABSTRACT) != 0;
196 }
197
198 /**
199 * Return {@code true} if the integer argument includes the
200 * {@code strictfp} modifier, {@code false} otherwise.
201 *
202 * @param mod a set of modifiers
203 * @return {@code true} if {@code mod} includes the
204 * {@code strictfp} modifier; {@code false} otherwise.
205 */
206 public static boolean isStrict(int mod) {
207 return (mod & STRICT) != 0;
208 }
209
210 /**
211 * Return a string describing the access modifier flags in
212 * the specified modifier. For example:
213 * <blockquote><pre>
214 * public final synchronized strictfp
215 * </pre></blockquote>
216 * The modifier names are returned in an order consistent with the
217 * suggested modifier orderings given in <a
218 * href="http://java.sun.com/docs/books/jls/second_edition/html/j.title.doc.html"><em>The
219 * Java Language Specification, Second Edition</em></a> sections
220 * <a href="http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#21613">§8.1.1</a>,
221 * <a href="http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#78091">§8.3.1</a>,
222 * <a href="http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#78188">§8.4.3</a>,
223 * <a href="http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#42018">§8.8.3</a>, and
224 * <a href="http://java.sun.com/docs/books/jls/second_edition/html/interfaces.doc.html#235947">§9.1.1</a>.
225 * The full modifier ordering used by this method is:
226 * <blockquote> {@code
227 * public protected private abstract static final transient
228 * volatile synchronized native strictfp
229 * interface } </blockquote>
230 * The {@code interface} modifier discussed in this class is
231 * not a true modifier in the Java language and it appears after
232 * all other modifiers listed by this method. This method may
233 * return a string of modifiers that are not valid modifiers of a
234 * Java entity; in other words, no checking is done on the
235 * possible validity of the combination of modifiers represented
236 * by the input.
237 *
238 * Note that to perform such checking for a known kind of entity,
239 * such as a constructor or method, first AND the argument of
240 * {@code toString} with the appropriate mask from a method like
241 * {@link #constructorModifiers} or {@link #methodModifiers}.
242 *
243 * @param mod a set of modifiers
244 * @return a string representation of the set of modifiers
245 * represented by {@code mod}
246 */
247 public static String toString(int mod) {
248 StringBuffer sb = new StringBuffer();
249 int len;
250
251 if ((mod & PUBLIC) != 0) sb.append("public ");
252 if ((mod & PROTECTED) != 0) sb.append("protected ");
253 if ((mod & PRIVATE) != 0) sb.append("private ");
254
255 /* Canonical order */
256 if ((mod & ABSTRACT) != 0) sb.append("abstract ");
257 if ((mod & STATIC) != 0) sb.append("static ");
258 if ((mod & FINAL) != 0) sb.append("final ");
259 if ((mod & TRANSIENT) != 0) sb.append("transient ");
260 if ((mod & VOLATILE) != 0) sb.append("volatile ");
261 if ((mod & SYNCHRONIZED) != 0) sb.append("synchronized ");
262 if ((mod & NATIVE) != 0) sb.append("native ");
263 if ((mod & STRICT) != 0) sb.append("strictfp ");
264 if ((mod & INTERFACE) != 0) sb.append("interface ");
265
266 if ((len = sb.length()) > 0) /* trim trailing space */
267 return sb.toString().substring(0, len-1);
268 return "";
269 }
270
271 /*
272 * Access modifier flag constants from <em>The Java Virtual
273 * Machine Specification, Second Edition</em>, tables 4.1, 4.4,
274 * 4.5, and 4.7.
275 */
276
277 /**
278 * The {@code int} value representing the {@code public}
279 * modifier.
280 */
281 public static final int PUBLIC = 0x00000001;
282
283 /**
284 * The {@code int} value representing the {@code private}
285 * modifier.
286 */
287 public static final int PRIVATE = 0x00000002;
288
289 /**
290 * The {@code int} value representing the {@code protected}
291 * modifier.
292 */
293 public static final int PROTECTED = 0x00000004;
294
295 /**
296 * The {@code int} value representing the {@code static}
297 * modifier.
298 */
299 public static final int STATIC = 0x00000008;
300
301 /**
302 * The {@code int} value representing the {@code final}
303 * modifier.
304 */
305 public static final int FINAL = 0x00000010;
306
307 /**
308 * The {@code int} value representing the {@code synchronized}
309 * modifier.
310 */
311 public static final int SYNCHRONIZED = 0x00000020;
312
313 /**
314 * The {@code int} value representing the {@code volatile}
315 * modifier.
316 */
317 public static final int VOLATILE = 0x00000040;
318
319 /**
320 * The {@code int} value representing the {@code transient}
321 * modifier.
322 */
323 public static final int TRANSIENT = 0x00000080;
324
325 /**
326 * The {@code int} value representing the {@code native}
327 * modifier.
328 */
329 public static final int NATIVE = 0x00000100;
330
331 /**
332 * The {@code int} value representing the {@code interface}
333 * modifier.
334 */
335 public static final int INTERFACE = 0x00000200;
336
337 /**
338 * The {@code int} value representing the {@code abstract}
339 * modifier.
340 */
341 public static final int ABSTRACT = 0x00000400;
342
343 /**
344 * The {@code int} value representing the {@code strictfp}
345 * modifier.
346 */
347 public static final int STRICT = 0x00000800;
348
349 // Bits not (yet) exposed in the public API either because they
350 // have different meanings for fields and methods and there is no
351 // way to distinguish between the two in this class, or because
352 // they are not Java programming language keywords
353 static final int BRIDGE = 0x00000040;
354 static final int VARARGS = 0x00000080;
355 static final int SYNTHETIC = 0x00001000;
356 static final int ANNOTATION= 0x00002000;
357 static final int ENUM = 0x00004000;
358 static boolean isSynthetic(int mod) {
359 return (mod & SYNTHETIC) != 0;
360 }
361
362 /**
363 * See JLSv3 section 8.1.1.
364 */
365 private static final int CLASS_MODIFIERS =
366 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
367 Modifier.ABSTRACT | Modifier.STATIC | Modifier.FINAL |
368 Modifier.STRICT;
369
370 /**
371 * See JLSv3 section 9.1.1.
372 */
373 private static final int INTERFACE_MODIFIERS =
374 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
375 Modifier.ABSTRACT | Modifier.STATIC | Modifier.STRICT;
376
377
378 /**
379 * See JLSv3 section 8.8.3.
380 */
381 private static final int CONSTRUCTOR_MODIFIERS =
382 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE;
383
384 /**
385 * See JLSv3 section 8.4.3.
386 */
387 private static final int METHOD_MODIFIERS =
388 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
389 Modifier.ABSTRACT | Modifier.STATIC | Modifier.FINAL |
390 Modifier.SYNCHRONIZED | Modifier.NATIVE | Modifier.STRICT;
391
392 /**
393 * See JLSv3 section 8.3.1.
394 */
395 private static final int FIELD_MODIFIERS =
396 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
397 Modifier.STATIC | Modifier.FINAL | Modifier.TRANSIENT |
398 Modifier.VOLATILE;
399
400 /**
401 * Return an {@code int} value OR-ing together the source language
402 * modifiers that can be applied to a class.
403 * @return an {@code int} value OR-ing together the source language
404 * modifiers that can be applied to a class.
405 *
406 * @jls3 8.1.1 Class Modifiers
407 * @since 1.7
408 */
409 public static int classModifiers() {
410 return CLASS_MODIFIERS;
411 }
412
413 /**
414 * Return an {@code int} value OR-ing together the source language
415 * modifiers that can be applied to an interface.
416 * @return an {@code int} value OR-ing together the source language
417 * modifiers that can be applied to an inteface.
418 *
419 * @jls3 9.1.1 Interface Modifiers
420 * @since 1.7
421 */
422 public static int interfaceModifiers() {
423 return INTERFACE_MODIFIERS;
424 }
425
426 /**
427 * Return an {@code int} value OR-ing together the source language
428 * modifiers that can be applied to a constructor.
429 * @return an {@code int} value OR-ing together the source language
430 * modifiers that can be applied to a constructor.
431 *
432 * @jls3 8.8.3 Constructor Modifiers
433 * @since 1.7
434 */
435 public static int constructorModifiers() {
436 return CONSTRUCTOR_MODIFIERS;
437 }
438
439 /**
440 * Return an {@code int} value OR-ing together the source language
441 * modifiers that can be applied to a method.
442 * @return an {@code int} value OR-ing together the source language
443 * modifiers that can be applied to a method.
444 *
445 * @jls3 8.4.3 Method Modifiers
446 * @since 1.7
447 */
448 public static int methodModifiers() {
449 return METHOD_MODIFIERS;
450 }
451
452
453 /**
454 * Return an {@code int} value OR-ing together the source language
455 * modifiers that can be applied to a field.
456 * @return an {@code int} value OR-ing together the source language
457 * modifiers that can be applied to a field.
458 *
459 * @jls3 8.3.1 Field Modifiers
460 * @since 1.7
461 */
462 public static int fieldModifiers() {
463 return FIELD_MODIFIERS;
464 }
465 }