1/* 2 * Copyright (c) 1996, 2013, 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 26package java.lang.reflect; 27 28import java.security.AccessController; 29import java.util.StringJoiner; 30import jdk.internal.reflect.LangReflectAccess; 31import jdk.internal.reflect.ReflectionFactory; 32 33/** 34 * The Modifier class provides {@code static} methods and 35 * constants to decode class and member access modifiers. The sets of 36 * modifiers are represented as integers with distinct bit positions 37 * representing different modifiers. The values for the constants 38 * representing the modifiers are taken from the tables in sections 4.1, 4.4, 4.5, and 4.7 of 39 * <cite>The Java™ Virtual Machine Specification</cite>. 40 * 41 * @see Class#getModifiers() 42 * @see Member#getModifiers() 43 * 44 * @author Nakul Saraiya 45 * @author Kenneth Russell 46 * @since 1.1 47 */ 48public class Modifier { 49 50 /* 51 * Bootstrapping protocol between java.lang and java.lang.reflect 52 * packages 53 */ 54 static { 55 ReflectionFactory factory = AccessController.doPrivileged( 56 new ReflectionFactory.GetReflectionFactoryAction()); 57 factory.setLangReflectAccess(new java.lang.reflect.ReflectAccess()); 58 } 59 60 /** 61 * Return {@code true} if the integer argument includes the 62 * {@code public} modifier, {@code false} otherwise. 63 * 64 * @param mod a set of modifiers 65 * @return {@code true} if {@code mod} includes the 66 * {@code public} modifier; {@code false} otherwise. 67 */ 68 public static boolean isPublic(int mod) { 69 return (mod & PUBLIC) != 0; 70 } 71 72 /** 73 * Return {@code true} if the integer argument includes the 74 * {@code private} modifier, {@code false} otherwise. 75 * 76 * @param mod a set of modifiers 77 * @return {@code true} if {@code mod} includes the 78 * {@code private} modifier; {@code false} otherwise. 79 */ 80 public static boolean isPrivate(int mod) { 81 return (mod & PRIVATE) != 0; 82 } 83 84 /** 85 * Return {@code true} if the integer argument includes the 86 * {@code protected} modifier, {@code false} otherwise. 87 * 88 * @param mod a set of modifiers 89 * @return {@code true} if {@code mod} includes the 90 * {@code protected} modifier; {@code false} otherwise. 91 */ 92 public static boolean isProtected(int mod) { 93 return (mod & PROTECTED) != 0; 94 } 95 96 /** 97 * Return {@code true} if the integer argument includes the 98 * {@code static} modifier, {@code false} otherwise. 99 * 100 * @param mod a set of modifiers 101 * @return {@code true} if {@code mod} includes the 102 * {@code static} modifier; {@code false} otherwise. 103 */ 104 public static boolean isStatic(int mod) { 105 return (mod & STATIC) != 0; 106 } 107 108 /** 109 * Return {@code true} if the integer argument includes the 110 * {@code final} modifier, {@code false} otherwise. 111 * 112 * @param mod a set of modifiers 113 * @return {@code true} if {@code mod} includes the 114 * {@code final} modifier; {@code false} otherwise. 115 */ 116 public static boolean isFinal(int mod) { 117 return (mod & FINAL) != 0; 118 } 119 120 /** 121 * Return {@code true} if the integer argument includes the 122 * {@code synchronized} modifier, {@code false} otherwise. 123 * 124 * @param mod a set of modifiers 125 * @return {@code true} if {@code mod} includes the 126 * {@code synchronized} modifier; {@code false} otherwise. 127 */ 128 public static boolean isSynchronized(int mod) { 129 return (mod & SYNCHRONIZED) != 0; 130 } 131 132 /** 133 * Return {@code true} if the integer argument includes the 134 * {@code volatile} modifier, {@code false} otherwise. 135 * 136 * @param mod a set of modifiers 137 * @return {@code true} if {@code mod} includes the 138 * {@code volatile} modifier; {@code false} otherwise. 139 */ 140 public static boolean isVolatile(int mod) { 141 return (mod & VOLATILE) != 0; 142 } 143 144 /** 145 * Return {@code true} if the integer argument includes the 146 * {@code transient} modifier, {@code false} otherwise. 147 * 148 * @param mod a set of modifiers 149 * @return {@code true} if {@code mod} includes the 150 * {@code transient} modifier; {@code false} otherwise. 151 */ 152 public static boolean isTransient(int mod) { 153 return (mod & TRANSIENT) != 0; 154 } 155 156 /** 157 * Return {@code true} if the integer argument includes the 158 * {@code native} modifier, {@code false} otherwise. 159 * 160 * @param mod a set of modifiers 161 * @return {@code true} if {@code mod} includes the 162 * {@code native} modifier; {@code false} otherwise. 163 */ 164 public static boolean isNative(int mod) { 165 return (mod & NATIVE) != 0; 166 } 167 168 /** 169 * Return {@code true} if the integer argument includes the 170 * {@code interface} modifier, {@code false} otherwise. 171 * 172 * @param mod a set of modifiers 173 * @return {@code true} if {@code mod} includes the 174 * {@code interface} modifier; {@code false} otherwise. 175 */ 176 public static boolean isInterface(int mod) { 177 return (mod & INTERFACE) != 0; 178 } 179 180 /** 181 * Return {@code true} if the integer argument includes the 182 * {@code abstract} modifier, {@code false} otherwise. 183 * 184 * @param mod a set of modifiers 185 * @return {@code true} if {@code mod} includes the 186 * {@code abstract} modifier; {@code false} otherwise. 187 */ 188 public static boolean isAbstract(int mod) { 189 return (mod & ABSTRACT) != 0; 190 } 191 192 /** 193 * Return {@code true} if the integer argument includes the 194 * {@code strictfp} modifier, {@code false} otherwise. 195 * 196 * @param mod a set of modifiers 197 * @return {@code true} if {@code mod} includes the 198 * {@code strictfp} modifier; {@code false} otherwise. 199 */ 200 public static boolean isStrict(int mod) { 201 return (mod & STRICT) != 0; 202 } 203 204 /** 205 * Return a string describing the access modifier flags in 206 * the specified modifier. For example: 207 * <blockquote><pre> 208 * public final synchronized strictfp 209 * </pre></blockquote> 210 * The modifier names are returned in an order consistent with the 211 * suggested modifier orderings given in sections 8.1.1, 8.3.1, 8.4.3, 8.8.3, and 9.1.1 of 212 * <cite>The Java™ Language Specification</cite>. 213 * The full modifier ordering used by this method is: 214 * <blockquote> {@code 215 * public protected private abstract static final transient 216 * volatile synchronized native strictfp 217 * interface } </blockquote> 218 * The {@code interface} modifier discussed in this class is 219 * not a true modifier in the Java language and it appears after 220 * all other modifiers listed by this method. This method may 221 * return a string of modifiers that are not valid modifiers of a 222 * Java entity; in other words, no checking is done on the 223 * possible validity of the combination of modifiers represented 224 * by the input. 225 * 226 * Note that to perform such checking for a known kind of entity, 227 * such as a constructor or method, first AND the argument of 228 * {@code toString} with the appropriate mask from a method like 229 * {@link #constructorModifiers} or {@link #methodModifiers}. 230 * 231 * @param mod a set of modifiers 232 * @return a string representation of the set of modifiers 233 * represented by {@code mod} 234 */ 235 public static String toString(int mod) { 236 StringJoiner sj = new StringJoiner(" "); 237 238 if ((mod & PUBLIC) != 0) sj.add("public"); 239 if ((mod & PROTECTED) != 0) sj.add("protected"); 240 if ((mod & PRIVATE) != 0) sj.add("private"); 241 242 /* Canonical order */ 243 if ((mod & ABSTRACT) != 0) sj.add("abstract"); 244 if ((mod & STATIC) != 0) sj.add("static"); 245 if ((mod & FINAL) != 0) sj.add("final"); 246 if ((mod & TRANSIENT) != 0) sj.add("transient"); 247 if ((mod & VOLATILE) != 0) sj.add("volatile"); 248 if ((mod & SYNCHRONIZED) != 0) sj.add("synchronized"); 249 if ((mod & NATIVE) != 0) sj.add("native"); 250 if ((mod & STRICT) != 0) sj.add("strictfp"); 251 if ((mod & INTERFACE) != 0) sj.add("interface"); 252 253 return sj.toString(); 254 } 255 256 /* 257 * Access modifier flag constants from tables 4.1, 4.4, 4.5, and 4.7 of 258 * <cite>The Java™ Virtual Machine Specification</cite> 259 */ 260 261 /** 262 * The {@code int} value representing the {@code public} 263 * modifier. 264 */ 265 public static final int PUBLIC = 0x00000001; 266 267 /** 268 * The {@code int} value representing the {@code private} 269 * modifier. 270 */ 271 public static final int PRIVATE = 0x00000002; 272 273 /** 274 * The {@code int} value representing the {@code protected} 275 * modifier. 276 */ 277 public static final int PROTECTED = 0x00000004; 278 279 /** 280 * The {@code int} value representing the {@code static} 281 * modifier. 282 */ 283 public static final int STATIC = 0x00000008; 284 285 /** 286 * The {@code int} value representing the {@code final} 287 * modifier. 288 */ 289 public static final int FINAL = 0x00000010; 290 291 /** 292 * The {@code int} value representing the {@code synchronized} 293 * modifier. 294 */ 295 public static final int SYNCHRONIZED = 0x00000020; 296 297 /** 298 * The {@code int} value representing the {@code volatile} 299 * modifier. 300 */ 301 public static final int VOLATILE = 0x00000040; 302 303 /** 304 * The {@code int} value representing the {@code transient} 305 * modifier. 306 */ 307 public static final int TRANSIENT = 0x00000080; 308 309 /** 310 * The {@code int} value representing the {@code native} 311 * modifier. 312 */ 313 public static final int NATIVE = 0x00000100; 314 315 /** 316 * The {@code int} value representing the {@code interface} 317 * modifier. 318 */ 319 public static final int INTERFACE = 0x00000200; 320 321 /** 322 * The {@code int} value representing the {@code abstract} 323 * modifier. 324 */ 325 public static final int ABSTRACT = 0x00000400; 326 327 /** 328 * The {@code int} value representing the {@code strictfp} 329 * modifier. 330 */ 331 public static final int STRICT = 0x00000800; 332 333 // Bits not (yet) exposed in the public API either because they 334 // have different meanings for fields and methods and there is no 335 // way to distinguish between the two in this class, or because 336 // they are not Java programming language keywords 337 static final int BRIDGE = 0x00000040; 338 static final int VARARGS = 0x00000080; 339 static final int SYNTHETIC = 0x00001000; 340 static final int ANNOTATION = 0x00002000; 341 static final int ENUM = 0x00004000; 342 static final int MANDATED = 0x00008000; 343 static boolean isSynthetic(int mod) { 344 return (mod & SYNTHETIC) != 0; 345 } 346 347 static boolean isMandated(int mod) { 348 return (mod & MANDATED) != 0; 349 } 350 351 // Note on the FOO_MODIFIERS fields and fooModifiers() methods: 352 // the sets of modifiers are not guaranteed to be constants 353 // across time and Java SE releases. Therefore, it would not be 354 // appropriate to expose an external interface to this information 355 // that would allow the values to be treated as Java-level 356 // constants since the values could be constant folded and updates 357 // to the sets of modifiers missed. Thus, the fooModifiers() 358 // methods return an unchanging values for a given release, but a 359 // value that can potentially change over time. 360 361 /** 362 * The Java source modifiers that can be applied to a class. 363 * @jls 8.1.1 Class Modifiers 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 * The Java source modifiers that can be applied to an interface. 372 * @jls 9.1.1 Interface Modifiers 373 */ 374 private static final int INTERFACE_MODIFIERS = 375 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE | 376 Modifier.ABSTRACT | Modifier.STATIC | Modifier.STRICT; 377 378 379 /** 380 * The Java source modifiers that can be applied to a constructor. 381 * @jls 8.8.3 Constructor Modifiers 382 */ 383 private static final int CONSTRUCTOR_MODIFIERS = 384 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE; 385 386 /** 387 * The Java source modifiers that can be applied to a method. 388 * @jls8.4.3 Method Modifiers 389 */ 390 private static final int METHOD_MODIFIERS = 391 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE | 392 Modifier.ABSTRACT | Modifier.STATIC | Modifier.FINAL | 393 Modifier.SYNCHRONIZED | Modifier.NATIVE | Modifier.STRICT; 394 395 /** 396 * The Java source modifiers that can be applied to a field. 397 * @jls 8.3.1 Field Modifiers 398 */ 399 private static final int FIELD_MODIFIERS = 400 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE | 401 Modifier.STATIC | Modifier.FINAL | Modifier.TRANSIENT | 402 Modifier.VOLATILE; 403 404 /** 405 * The Java source modifiers that can be applied to a method or constructor parameter. 406 * @jls 8.4.1 Formal Parameters 407 */ 408 private static final int PARAMETER_MODIFIERS = 409 Modifier.FINAL; 410 411 /** 412 * 413 */ 414 static final int ACCESS_MODIFIERS = 415 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE; 416 417 /** 418 * Return an {@code int} value OR-ing together the source language 419 * modifiers that can be applied to a class. 420 * @return an {@code int} value OR-ing together the source language 421 * modifiers that can be applied to a class. 422 * 423 * @jls 8.1.1 Class Modifiers 424 * @since 1.7 425 */ 426 public static int classModifiers() { 427 return CLASS_MODIFIERS; 428 } 429 430 /** 431 * Return an {@code int} value OR-ing together the source language 432 * modifiers that can be applied to an interface. 433 * @return an {@code int} value OR-ing together the source language 434 * modifiers that can be applied to an interface. 435 * 436 * @jls 9.1.1 Interface Modifiers 437 * @since 1.7 438 */ 439 public static int interfaceModifiers() { 440 return INTERFACE_MODIFIERS; 441 } 442 443 /** 444 * Return an {@code int} value OR-ing together the source language 445 * modifiers that can be applied to a constructor. 446 * @return an {@code int} value OR-ing together the source language 447 * modifiers that can be applied to a constructor. 448 * 449 * @jls 8.8.3 Constructor Modifiers 450 * @since 1.7 451 */ 452 public static int constructorModifiers() { 453 return CONSTRUCTOR_MODIFIERS; 454 } 455 456 /** 457 * Return an {@code int} value OR-ing together the source language 458 * modifiers that can be applied to a method. 459 * @return an {@code int} value OR-ing together the source language 460 * modifiers that can be applied to a method. 461 * 462 * @jls 8.4.3 Method Modifiers 463 * @since 1.7 464 */ 465 public static int methodModifiers() { 466 return METHOD_MODIFIERS; 467 } 468 469 /** 470 * Return an {@code int} value OR-ing together the source language 471 * modifiers that can be applied to a field. 472 * @return an {@code int} value OR-ing together the source language 473 * modifiers that can be applied to a field. 474 * 475 * @jls 8.3.1 Field Modifiers 476 * @since 1.7 477 */ 478 public static int fieldModifiers() { 479 return FIELD_MODIFIERS; 480 } 481 482 /** 483 * Return an {@code int} value OR-ing together the source language 484 * modifiers that can be applied to a parameter. 485 * @return an {@code int} value OR-ing together the source language 486 * modifiers that can be applied to a parameter. 487 * 488 * @jls 8.4.1 Formal Parameters 489 * @since 1.8 490 */ 491 public static int parameterModifiers() { 492 return PARAMETER_MODIFIERS; 493 } 494} 495