1 /*
2 * Copyright (c) 1996, 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 java.lang.reflect;
27
28 import java.util.StringJoiner;
29
30 /**
31 * The Modifier class provides {@code static} methods and
32 * constants to decode class and member access modifiers. The sets of
33 * modifiers are represented as integers with distinct bit positions
34 * representing different modifiers. The values for the constants
35 * representing the modifiers are taken from the tables in sections 4.1, 4.4, 4.5, and 4.7 of
36 * <cite>The Java™ Virtual Machine Specification</cite>.
37 *
38 * @see Class#getModifiers()
39 * @see Member#getModifiers()
40 *
41 * @author Nakul Saraiya
42 * @author Kenneth Russell
43 * @since 1.1
44 */
45 public class Modifier {
46 /**
47 * Do not call.
48 */
49 private Modifier() {throw new AssertionError();}
50
51
52 /**
53 * Return {@code true} if the integer argument includes the
54 * {@code public} modifier, {@code false} otherwise.
55 *
56 * @param mod a set of modifiers
57 * @return {@code true} if {@code mod} includes the
58 * {@code public} modifier; {@code false} otherwise.
59 */
60 public static boolean isPublic(int mod) {
61 return (mod & PUBLIC) != 0;
62 }
63
64 /**
65 * Return {@code true} if the integer argument includes the
66 * {@code private} modifier, {@code false} otherwise.
67 *
68 * @param mod a set of modifiers
69 * @return {@code true} if {@code mod} includes the
70 * {@code private} modifier; {@code false} otherwise.
71 */
72 public static boolean isPrivate(int mod) {
73 return (mod & PRIVATE) != 0;
74 }
75
76 /**
77 * Return {@code true} if the integer argument includes the
78 * {@code protected} modifier, {@code false} otherwise.
79 *
80 * @param mod a set of modifiers
81 * @return {@code true} if {@code mod} includes the
82 * {@code protected} modifier; {@code false} otherwise.
83 */
84 public static boolean isProtected(int mod) {
85 return (mod & PROTECTED) != 0;
86 }
87
88 /**
89 * Return {@code true} if the integer argument includes the
90 * {@code static} modifier, {@code false} otherwise.
91 *
92 * @param mod a set of modifiers
93 * @return {@code true} if {@code mod} includes the
94 * {@code static} modifier; {@code false} otherwise.
95 */
96 public static boolean isStatic(int mod) {
97 return (mod & STATIC) != 0;
98 }
99
100 /**
101 * Return {@code true} if the integer argument includes the
102 * {@code final} modifier, {@code false} otherwise.
103 *
104 * @param mod a set of modifiers
105 * @return {@code true} if {@code mod} includes the
106 * {@code final} modifier; {@code false} otherwise.
107 */
108 public static boolean isFinal(int mod) {
109 return (mod & FINAL) != 0;
110 }
111
112 /**
113 * Return {@code true} if the integer argument includes the
114 * {@code synchronized} modifier, {@code false} otherwise.
115 *
116 * @param mod a set of modifiers
117 * @return {@code true} if {@code mod} includes the
118 * {@code synchronized} modifier; {@code false} otherwise.
119 */
120 public static boolean isSynchronized(int mod) {
121 return (mod & SYNCHRONIZED) != 0;
122 }
123
124 /**
125 * Return {@code true} if the integer argument includes the
126 * {@code volatile} modifier, {@code false} otherwise.
127 *
128 * @param mod a set of modifiers
129 * @return {@code true} if {@code mod} includes the
130 * {@code volatile} modifier; {@code false} otherwise.
131 */
132 public static boolean isVolatile(int mod) {
133 return (mod & VOLATILE) != 0;
134 }
135
136 /**
137 * Return {@code true} if the integer argument includes the
138 * {@code transient} modifier, {@code false} otherwise.
139 *
140 * @param mod a set of modifiers
141 * @return {@code true} if {@code mod} includes the
142 * {@code transient} modifier; {@code false} otherwise.
143 */
144 public static boolean isTransient(int mod) {
145 return (mod & TRANSIENT) != 0;
146 }
147
148 /**
149 * Return {@code true} if the integer argument includes the
150 * {@code native} modifier, {@code false} otherwise.
151 *
152 * @param mod a set of modifiers
153 * @return {@code true} if {@code mod} includes the
154 * {@code native} modifier; {@code false} otherwise.
155 */
156 public static boolean isNative(int mod) {
157 return (mod & NATIVE) != 0;
158 }
159
160 /**
161 * Return {@code true} if the integer argument includes the
162 * {@code interface} modifier, {@code false} otherwise.
163 *
164 * @param mod a set of modifiers
165 * @return {@code true} if {@code mod} includes the
166 * {@code interface} modifier; {@code false} otherwise.
167 */
168 public static boolean isInterface(int mod) {
169 return (mod & INTERFACE) != 0;
170 }
171
172 /**
173 * Return {@code true} if the integer argument includes the
174 * {@code abstract} modifier, {@code false} otherwise.
175 *
176 * @param mod a set of modifiers
177 * @return {@code true} if {@code mod} includes the
178 * {@code abstract} modifier; {@code false} otherwise.
179 */
180 public static boolean isAbstract(int mod) {
181 return (mod & ABSTRACT) != 0;
182 }
183
184 /**
185 * Return {@code true} if the integer argument includes the
186 * {@code strictfp} modifier, {@code false} otherwise.
187 *
188 * @param mod a set of modifiers
189 * @return {@code true} if {@code mod} includes the
190 * {@code strictfp} modifier; {@code false} otherwise.
191 */
192 public static boolean isStrict(int mod) {
193 return (mod & STRICT) != 0;
194 }
195
196 /**
197 * Return a string describing the access modifier flags in
198 * the specified modifier. For example:
199 * <blockquote><pre>
200 * public final synchronized strictfp
201 * </pre></blockquote>
202 * The modifier names are returned in an order consistent with the
203 * suggested modifier orderings given in sections 8.1.1, 8.3.1, 8.4.3, 8.8.3, and 9.1.1 of
204 * <cite>The Java™ Language Specification</cite>.
205 * The full modifier ordering used by this method is:
206 * <blockquote> {@code
207 * public protected private abstract static final transient
208 * volatile synchronized native strictfp
209 * interface } </blockquote>
210 * The {@code interface} modifier discussed in this class is
211 * not a true modifier in the Java language and it appears after
212 * all other modifiers listed by this method. This method may
213 * return a string of modifiers that are not valid modifiers of a
214 * Java entity; in other words, no checking is done on the
215 * possible validity of the combination of modifiers represented
216 * by the input.
217 *
218 * Note that to perform such checking for a known kind of entity,
219 * such as a constructor or method, first AND the argument of
220 * {@code toString} with the appropriate mask from a method like
221 * {@link #constructorModifiers} or {@link #methodModifiers}.
222 *
223 * @param mod a set of modifiers
224 * @return a string representation of the set of modifiers
225 * represented by {@code mod}
226 */
227 public static String toString(int mod) {
228 StringJoiner sj = new StringJoiner(" ");
229
230 if ((mod & PUBLIC) != 0) sj.add("public");
231 if ((mod & PROTECTED) != 0) sj.add("protected");
232 if ((mod & PRIVATE) != 0) sj.add("private");
233
234 /* Canonical order */
235 if ((mod & ABSTRACT) != 0) sj.add("abstract");
236 if ((mod & STATIC) != 0) sj.add("static");
237 if ((mod & FINAL) != 0) sj.add("final");
238 if ((mod & TRANSIENT) != 0) sj.add("transient");
239 if ((mod & VOLATILE) != 0) sj.add("volatile");
240 if ((mod & SYNCHRONIZED) != 0) sj.add("synchronized");
241 if ((mod & NATIVE) != 0) sj.add("native");
242 if ((mod & STRICT) != 0) sj.add("strictfp");
243 if ((mod & INTERFACE) != 0) sj.add("interface");
244
245 return sj.toString();
246 }
247
248 /*
249 * Access modifier flag constants from tables 4.1, 4.4, 4.5, and 4.7 of
250 * <cite>The Java™ Virtual Machine Specification</cite>
251 */
252
253 /**
254 * The {@code int} value representing the {@code public}
255 * modifier.
256 */
257 public static final int PUBLIC = 0x00000001;
258
259 /**
260 * The {@code int} value representing the {@code private}
261 * modifier.
262 */
263 public static final int PRIVATE = 0x00000002;
264
265 /**
266 * The {@code int} value representing the {@code protected}
267 * modifier.
268 */
269 public static final int PROTECTED = 0x00000004;
270
271 /**
272 * The {@code int} value representing the {@code static}
273 * modifier.
274 */
275 public static final int STATIC = 0x00000008;
276
277 /**
278 * The {@code int} value representing the {@code final}
279 * modifier.
280 */
281 public static final int FINAL = 0x00000010;
282
283 /**
284 * The {@code int} value representing the {@code synchronized}
285 * modifier.
286 */
287 public static final int SYNCHRONIZED = 0x00000020;
288
289 /**
290 * The {@code int} value representing the {@code volatile}
291 * modifier.
292 */
293 public static final int VOLATILE = 0x00000040;
294
295 /**
296 * The {@code int} value representing the {@code transient}
297 * modifier.
298 */
299 public static final int TRANSIENT = 0x00000080;
300
301 /**
302 * The {@code int} value representing the {@code native}
303 * modifier.
304 */
305 public static final int NATIVE = 0x00000100;
306
307 /**
308 * The {@code int} value representing the {@code interface}
309 * modifier.
310 */
311 public static final int INTERFACE = 0x00000200;
312
313 /**
314 * The {@code int} value representing the {@code abstract}
315 * modifier.
316 */
317 public static final int ABSTRACT = 0x00000400;
318
319 /**
320 * The {@code int} value representing the {@code strictfp}
321 * modifier.
322 */
323 public static final int STRICT = 0x00000800;
324
325 // Bits not (yet) exposed in the public API either because they
326 // have different meanings for fields and methods and there is no
327 // way to distinguish between the two in this class, or because
328 // they are not Java programming language keywords
329 static final int BRIDGE = 0x00000040;
330 static final int VARARGS = 0x00000080;
331 static final int SYNTHETIC = 0x00001000;
332 static final int ANNOTATION = 0x00002000;
333 static final int ENUM = 0x00004000;
334 static final int MANDATED = 0x00008000;
335 static boolean isSynthetic(int mod) {
336 return (mod & SYNTHETIC) != 0;
337 }
338
339 static boolean isMandated(int mod) {
340 return (mod & MANDATED) != 0;
341 }
342
343 // Note on the FOO_MODIFIERS fields and fooModifiers() methods:
344 // the sets of modifiers are not guaranteed to be constants
345 // across time and Java SE releases. Therefore, it would not be
346 // appropriate to expose an external interface to this information
347 // that would allow the values to be treated as Java-level
348 // constants since the values could be constant folded and updates
349 // to the sets of modifiers missed. Thus, the fooModifiers()
350 // methods return an unchanging values for a given release, but a
351 // value that can potentially change over time.
352
353 /**
354 * The Java source modifiers that can be applied to a class.
355 * @jls 8.1.1 Class Modifiers
356 */
357 private static final int CLASS_MODIFIERS =
358 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
359 Modifier.ABSTRACT | Modifier.STATIC | Modifier.FINAL |
360 Modifier.STRICT;
361
362 /**
363 * The Java source modifiers that can be applied to an interface.
364 * @jls 9.1.1 Interface Modifiers
365 */
366 private static final int INTERFACE_MODIFIERS =
367 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
368 Modifier.ABSTRACT | Modifier.STATIC | Modifier.STRICT;
369
370
371 /**
372 * The Java source modifiers that can be applied to a constructor.
373 * @jls 8.8.3 Constructor Modifiers
374 */
375 private static final int CONSTRUCTOR_MODIFIERS =
376 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE;
377
378 /**
379 * The Java source modifiers that can be applied to a method.
380 * @jls 8.4.3 Method Modifiers
381 */
382 private static final int METHOD_MODIFIERS =
383 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
384 Modifier.ABSTRACT | Modifier.STATIC | Modifier.FINAL |
385 Modifier.SYNCHRONIZED | Modifier.NATIVE | Modifier.STRICT;
386
387 /**
388 * The Java source modifiers that can be applied to a field.
389 * @jls 8.3.1 Field Modifiers
390 */
391 private static final int FIELD_MODIFIERS =
392 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
393 Modifier.STATIC | Modifier.FINAL | Modifier.TRANSIENT |
394 Modifier.VOLATILE;
395
396 /**
397 * The Java source modifiers that can be applied to a method or constructor parameter.
398 * @jls 8.4.1 Formal Parameters
399 */
400 private static final int PARAMETER_MODIFIERS =
401 Modifier.FINAL;
402
403 static final int ACCESS_MODIFIERS =
404 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE;
405
406 /**
407 * Return an {@code int} value OR-ing together the source language
408 * modifiers that can be applied to a class.
409 * @return an {@code int} value OR-ing together the source language
410 * modifiers that can be applied to a class.
411 *
412 * @jls 8.1.1 Class Modifiers
413 * @since 1.7
414 */
415 public static int classModifiers() {
416 return CLASS_MODIFIERS;
417 }
418
419 /**
420 * Return an {@code int} value OR-ing together the source language
421 * modifiers that can be applied to an interface.
422 * @return an {@code int} value OR-ing together the source language
423 * modifiers that can be applied to an interface.
424 *
425 * @jls 9.1.1 Interface Modifiers
426 * @since 1.7
427 */
428 public static int interfaceModifiers() {
429 return INTERFACE_MODIFIERS;
430 }
431
432 /**
433 * Return an {@code int} value OR-ing together the source language
434 * modifiers that can be applied to a constructor.
435 * @return an {@code int} value OR-ing together the source language
436 * modifiers that can be applied to a constructor.
437 *
438 * @jls 8.8.3 Constructor Modifiers
439 * @since 1.7
440 */
441 public static int constructorModifiers() {
442 return CONSTRUCTOR_MODIFIERS;
443 }
444
445 /**
446 * Return an {@code int} value OR-ing together the source language
447 * modifiers that can be applied to a method.
448 * @return an {@code int} value OR-ing together the source language
449 * modifiers that can be applied to a method.
450 *
451 * @jls 8.4.3 Method Modifiers
452 * @since 1.7
453 */
454 public static int methodModifiers() {
455 return METHOD_MODIFIERS;
456 }
457
458 /**
459 * Return an {@code int} value OR-ing together the source language
460 * modifiers that can be applied to a field.
461 * @return an {@code int} value OR-ing together the source language
462 * modifiers that can be applied to a field.
463 *
464 * @jls 8.3.1 Field Modifiers
465 * @since 1.7
466 */
467 public static int fieldModifiers() {
468 return FIELD_MODIFIERS;
469 }
470
471 /**
472 * Return an {@code int} value OR-ing together the source language
473 * modifiers that can be applied to a parameter.
474 * @return an {@code int} value OR-ing together the source language
475 * modifiers that can be applied to a parameter.
476 *
477 * @jls 8.4.1 Formal Parameters
478 * @since 1.8
479 */
480 public static int parameterModifiers() {
481 return PARAMETER_MODIFIERS;
482 }
483 }