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 36 * {@jvms 4.1}, {@jvms 4.4}, {@jvms 4.5}, and {@jvms 4.7} of 37 * <cite>The Java Virtual Machine Specification</cite>. 38 * 39 * @see Class#getModifiers() 40 * @see Member#getModifiers() 41 * 42 * @author Nakul Saraiya 43 * @author Kenneth Russell 44 * @since 1.1 45 */ 46 public class Modifier { 47 /** 48 * Do not call. 49 */ 50 private Modifier() {throw new AssertionError();} 51 52 53 /** 54 * Return {@code true} if the integer argument includes the 55 * {@code public} modifier, {@code false} otherwise. 56 * 57 * @param mod a set of modifiers 58 * @return {@code true} if {@code mod} includes the 59 * {@code public} modifier; {@code false} otherwise. 60 */ 61 public static boolean isPublic(int mod) { 62 return (mod & PUBLIC) != 0; 63 } 64 65 /** 66 * Return {@code true} if the integer argument includes the 67 * {@code private} modifier, {@code false} otherwise. 68 * 69 * @param mod a set of modifiers 70 * @return {@code true} if {@code mod} includes the 71 * {@code private} modifier; {@code false} otherwise. 72 */ 73 public static boolean isPrivate(int mod) { 74 return (mod & PRIVATE) != 0; 75 } 76 77 /** 78 * Return {@code true} if the integer argument includes the 79 * {@code protected} modifier, {@code false} otherwise. 80 * 81 * @param mod a set of modifiers 82 * @return {@code true} if {@code mod} includes the 83 * {@code protected} modifier; {@code false} otherwise. 84 */ 85 public static boolean isProtected(int mod) { 86 return (mod & PROTECTED) != 0; 87 } 88 89 /** 90 * Return {@code true} if the integer argument includes the 91 * {@code static} modifier, {@code false} otherwise. 92 * 93 * @param mod a set of modifiers 94 * @return {@code true} if {@code mod} includes the 95 * {@code static} modifier; {@code false} otherwise. 96 */ 97 public static boolean isStatic(int mod) { 98 return (mod & STATIC) != 0; 99 } 100 101 /** 102 * Return {@code true} if the integer argument includes the 103 * {@code final} modifier, {@code false} otherwise. 104 * 105 * @param mod a set of modifiers 106 * @return {@code true} if {@code mod} includes the 107 * {@code final} modifier; {@code false} otherwise. 108 */ 109 public static boolean isFinal(int mod) { 110 return (mod & FINAL) != 0; 111 } 112 113 /** 114 * Return {@code true} if the integer argument includes the 115 * {@code synchronized} modifier, {@code false} otherwise. 116 * 117 * @param mod a set of modifiers 118 * @return {@code true} if {@code mod} includes the 119 * {@code synchronized} modifier; {@code false} otherwise. 120 */ 121 public static boolean isSynchronized(int mod) { 122 return (mod & SYNCHRONIZED) != 0; 123 } 124 125 /** 126 * Return {@code true} if the integer argument includes the 127 * {@code volatile} modifier, {@code false} otherwise. 128 * 129 * @param mod a set of modifiers 130 * @return {@code true} if {@code mod} includes the 131 * {@code volatile} modifier; {@code false} otherwise. 132 */ 133 public static boolean isVolatile(int mod) { 134 return (mod & VOLATILE) != 0; 135 } 136 137 /** 138 * Return {@code true} if the integer argument includes the 139 * {@code transient} modifier, {@code false} otherwise. 140 * 141 * @param mod a set of modifiers 142 * @return {@code true} if {@code mod} includes the 143 * {@code transient} modifier; {@code false} otherwise. 144 */ 145 public static boolean isTransient(int mod) { 146 return (mod & TRANSIENT) != 0; 147 } 148 149 /** 150 * Return {@code true} if the integer argument includes the 151 * {@code native} modifier, {@code false} otherwise. 152 * 153 * @param mod a set of modifiers 154 * @return {@code true} if {@code mod} includes the 155 * {@code native} modifier; {@code false} otherwise. 156 */ 157 public static boolean isNative(int mod) { 158 return (mod & NATIVE) != 0; 159 } 160 161 /** 162 * Return {@code true} if the integer argument includes the 163 * {@code interface} modifier, {@code false} otherwise. 164 * 165 * @param mod a set of modifiers 166 * @return {@code true} if {@code mod} includes the 167 * {@code interface} modifier; {@code false} otherwise. 168 */ 169 public static boolean isInterface(int mod) { 170 return (mod & INTERFACE) != 0; 171 } 172 173 /** 174 * Return {@code true} if the integer argument includes the 175 * {@code abstract} modifier, {@code false} otherwise. 176 * 177 * @param mod a set of modifiers 178 * @return {@code true} if {@code mod} includes the 179 * {@code abstract} modifier; {@code false} otherwise. 180 */ 181 public static boolean isAbstract(int mod) { 182 return (mod & ABSTRACT) != 0; 183 } 184 185 /** 186 * Return {@code true} if the integer argument includes the 187 * {@code strictfp} modifier, {@code false} otherwise. 188 * 189 * @param mod a set of modifiers 190 * @return {@code true} if {@code mod} includes the 191 * {@code strictfp} modifier; {@code false} otherwise. 192 */ 193 public static boolean isStrict(int mod) { 194 return (mod & STRICT) != 0; 195 } 196 197 /** 198 * Return a string describing the access modifier flags in 199 * the specified modifier. For example: 200 * <blockquote><pre> 201 * public final synchronized strictfp 202 * </pre></blockquote> 203 * The modifier names are returned in an order consistent with the 204 * suggested modifier orderings given in sections 8.1.1, 8.3.1, 8.4.3, 8.8.3, and 9.1.1 of 205 * <cite>The Java Language Specification</cite>. 206 * The full modifier ordering used by this method is: 207 * <blockquote> {@code 208 * public protected private abstract static final transient 209 * volatile synchronized native strictfp 210 * interface } </blockquote> 211 * The {@code interface} modifier discussed in this class is 212 * not a true modifier in the Java language and it appears after 213 * all other modifiers listed by this method. This method may 214 * return a string of modifiers that are not valid modifiers of a 215 * Java entity; in other words, no checking is done on the 216 * possible validity of the combination of modifiers represented 217 * by the input. 218 * 219 * Note that to perform such checking for a known kind of entity, 220 * such as a constructor or method, first AND the argument of 221 * {@code toString} with the appropriate mask from a method like 222 * {@link #constructorModifiers} or {@link #methodModifiers}. 223 * 224 * @param mod a set of modifiers 225 * @return a string representation of the set of modifiers 226 * represented by {@code mod} 227 */ 228 public static String toString(int mod) { 229 StringJoiner sj = new StringJoiner(" "); 230 231 if ((mod & PUBLIC) != 0) sj.add("public"); 232 if ((mod & PROTECTED) != 0) sj.add("protected"); 233 if ((mod & PRIVATE) != 0) sj.add("private"); 234 235 /* Canonical order */ 236 if ((mod & ABSTRACT) != 0) sj.add("abstract"); 237 if ((mod & STATIC) != 0) sj.add("static"); 238 if ((mod & FINAL) != 0) sj.add("final"); 239 if ((mod & TRANSIENT) != 0) sj.add("transient"); 240 if ((mod & VOLATILE) != 0) sj.add("volatile"); 241 if ((mod & SYNCHRONIZED) != 0) sj.add("synchronized"); 242 if ((mod & NATIVE) != 0) sj.add("native"); 243 if ((mod & STRICT) != 0) sj.add("strictfp"); 244 if ((mod & INTERFACE) != 0) sj.add("interface"); 245 246 return sj.toString(); 247 } 248 249 /* 250 * Access modifier flag constants from tables 4.1, 4.4, 4.5, and 4.7 of 251 * <cite>The Java Virtual Machine Specification</cite> 252 */ 253 254 /** 255 * The {@code int} value representing the {@code public} 256 * modifier. 257 * @see AccessFlag#PUBLIC 258 */ 259 public static final int PUBLIC = 0x00000001; 260 261 /** 262 * The {@code int} value representing the {@code private} 263 * modifier. 264 * @see AccessFlag#PRIVATE 265 */ 266 public static final int PRIVATE = 0x00000002; 267 268 /** 269 * The {@code int} value representing the {@code protected} 270 * modifier. 271 * @see AccessFlag#PROTECTED 272 */ 273 public static final int PROTECTED = 0x00000004; 274 275 /** 276 * The {@code int} value representing the {@code static} 277 * modifier. 278 * @see AccessFlag#STATIC 279 */ 280 public static final int STATIC = 0x00000008; 281 282 /** 283 * The {@code int} value representing the {@code final} 284 * modifier. 285 * @see AccessFlag#FINAL 286 */ 287 public static final int FINAL = 0x00000010; 288 289 /** 290 * The {@code int} value representing the {@code synchronized} 291 * modifier. 292 * @see AccessFlag#SYNCHRONIZED 293 */ 294 public static final int SYNCHRONIZED = 0x00000020; 295 296 /** 297 * The {@code int} value representing the {@code volatile} 298 * modifier. 299 * @see AccessFlag#VOLATILE 300 */ 301 public static final int VOLATILE = 0x00000040; 302 303 /** 304 * The {@code int} value representing the {@code transient} 305 * modifier. 306 * @see AccessFlag#TRANSIENT 307 */ 308 public static final int TRANSIENT = 0x00000080; 309 310 /** 311 * The {@code int} value representing the {@code native} 312 * modifier. 313 * @see AccessFlag#NATIVE 314 */ 315 public static final int NATIVE = 0x00000100; 316 317 /** 318 * The {@code int} value representing the {@code interface} 319 * modifier. 320 * @see AccessFlag#INTERFACE 321 */ 322 public static final int INTERFACE = 0x00000200; 323 324 /** 325 * The {@code int} value representing the {@code abstract} 326 * modifier. 327 * @see AccessFlag#ABSTRACT 328 */ 329 public static final int ABSTRACT = 0x00000400; 330 331 /** 332 * The {@code int} value representing the {@code strictfp} 333 * modifier. 334 * @see AccessFlag#STRICT 335 */ 336 public static final int STRICT = 0x00000800; 337 338 // Bits not (yet) exposed in the public API either because they 339 // have different meanings for fields and methods and there is no 340 // way to distinguish between the two in this class, or because 341 // they are not Java programming language keywords 342 static final int BRIDGE = 0x00000040; 343 static final int VARARGS = 0x00000080; 344 static final int SYNTHETIC = 0x00001000; 345 static final int ANNOTATION = 0x00002000; 346 static final int ENUM = 0x00004000; 347 static final int MANDATED = 0x00008000; 348 static boolean isSynthetic(int mod) { 349 return (mod & SYNTHETIC) != 0; 350 } 351 352 static boolean isMandated(int mod) { 353 return (mod & MANDATED) != 0; 354 } 355 356 // Note on the FOO_MODIFIERS fields and fooModifiers() methods: 357 // the sets of modifiers are not guaranteed to be constants 358 // across time and Java SE releases. Therefore, it would not be 359 // appropriate to expose an external interface to this information 360 // that would allow the values to be treated as Java-level 361 // constants since the values could be constant folded and updates 362 // to the sets of modifiers missed. Thus, the fooModifiers() 363 // methods return an unchanging values for a given release, but a 364 // value that can potentially change over time. 365 366 /** 367 * The Java source modifiers that can be applied to a class. 368 * @jls 8.1.1 Class Modifiers 369 */ 370 private static final int CLASS_MODIFIERS = 371 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE | 372 Modifier.ABSTRACT | Modifier.STATIC | Modifier.FINAL | 373 Modifier.STRICT; 374 375 /** 376 * The Java source modifiers that can be applied to an interface. 377 * @jls 9.1.1 Interface Modifiers 378 */ 379 private static final int INTERFACE_MODIFIERS = 380 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE | 381 Modifier.ABSTRACT | Modifier.STATIC | Modifier.STRICT; 382 383 384 /** 385 * The Java source modifiers that can be applied to a constructor. 386 * @jls 8.8.3 Constructor Modifiers 387 */ 388 private static final int CONSTRUCTOR_MODIFIERS = 389 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE; 390 391 /** 392 * The Java source modifiers that can be applied to a method. 393 * @jls 8.4.3 Method Modifiers 394 */ 395 private static final int METHOD_MODIFIERS = 396 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE | 397 Modifier.ABSTRACT | Modifier.STATIC | Modifier.FINAL | 398 Modifier.SYNCHRONIZED | Modifier.NATIVE | Modifier.STRICT; 399 400 /** 401 * The Java source modifiers that can be applied to a field. 402 * @jls 8.3.1 Field Modifiers 403 */ 404 private static final int FIELD_MODIFIERS = 405 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE | 406 Modifier.STATIC | Modifier.FINAL | Modifier.TRANSIENT | 407 Modifier.VOLATILE; 408 409 /** 410 * The Java source modifiers that can be applied to a method or constructor parameter. 411 * @jls 8.4.1 Formal Parameters 412 */ 413 private static final int PARAMETER_MODIFIERS = 414 Modifier.FINAL; 415 416 static final int ACCESS_MODIFIERS = 417 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE; 418 419 /** 420 * Return an {@code int} value OR-ing together the source language 421 * modifiers that can be applied to a class. 422 * @return an {@code int} value OR-ing together the source language 423 * modifiers that can be applied to a class. 424 * 425 * @jls 8.1.1 Class Modifiers 426 * @since 1.7 427 */ 428 public static int classModifiers() { 429 return CLASS_MODIFIERS; 430 } 431 432 /** 433 * Return an {@code int} value OR-ing together the source language 434 * modifiers that can be applied to an interface. 435 * @return an {@code int} value OR-ing together the source language 436 * modifiers that can be applied to an interface. 437 * 438 * @jls 9.1.1 Interface Modifiers 439 * @since 1.7 440 */ 441 public static int interfaceModifiers() { 442 return INTERFACE_MODIFIERS; 443 } 444 445 /** 446 * Return an {@code int} value OR-ing together the source language 447 * modifiers that can be applied to a constructor. 448 * @return an {@code int} value OR-ing together the source language 449 * modifiers that can be applied to a constructor. 450 * 451 * @jls 8.8.3 Constructor Modifiers 452 * @since 1.7 453 */ 454 public static int constructorModifiers() { 455 return CONSTRUCTOR_MODIFIERS; 456 } 457 458 /** 459 * Return an {@code int} value OR-ing together the source language 460 * modifiers that can be applied to a method. 461 * @return an {@code int} value OR-ing together the source language 462 * modifiers that can be applied to a method. 463 * 464 * @jls 8.4.3 Method Modifiers 465 * @since 1.7 466 */ 467 public static int methodModifiers() { 468 return METHOD_MODIFIERS; 469 } 470 471 /** 472 * Return an {@code int} value OR-ing together the source language 473 * modifiers that can be applied to a field. 474 * @return an {@code int} value OR-ing together the source language 475 * modifiers that can be applied to a field. 476 * 477 * @jls 8.3.1 Field Modifiers 478 * @since 1.7 479 */ 480 public static int fieldModifiers() { 481 return FIELD_MODIFIERS; 482 } 483 484 /** 485 * Return an {@code int} value OR-ing together the source language 486 * modifiers that can be applied to a parameter. 487 * @return an {@code int} value OR-ing together the source language 488 * modifiers that can be applied to a parameter. 489 * 490 * @jls 8.4.1 Formal Parameters 491 * @since 1.8 492 */ 493 public static int parameterModifiers() { 494 return PARAMETER_MODIFIERS; 495 } 496 }