1/* 2 * Copyright (c) 2003, 2014, 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.util; 27 28import jdk.internal.misc.SharedSecrets; 29 30/** 31 * A specialized {@link Set} implementation for use with enum types. All of 32 * the elements in an enum set must come from a single enum type that is 33 * specified, explicitly or implicitly, when the set is created. Enum sets 34 * are represented internally as bit vectors. This representation is 35 * extremely compact and efficient. The space and time performance of this 36 * class should be good enough to allow its use as a high-quality, typesafe 37 * alternative to traditional {@code int}-based "bit flags." Even bulk 38 * operations (such as {@code containsAll} and {@code retainAll}) should 39 * run very quickly if their argument is also an enum set. 40 * 41 * <p>The iterator returned by the {@code iterator} method traverses the 42 * elements in their <i>natural order</i> (the order in which the enum 43 * constants are declared). The returned iterator is <i>weakly 44 * consistent</i>: it will never throw {@link ConcurrentModificationException} 45 * and it may or may not show the effects of any modifications to the set that 46 * occur while the iteration is in progress. 47 * 48 * <p>Null elements are not permitted. Attempts to insert a null element 49 * will throw {@link NullPointerException}. Attempts to test for the 50 * presence of a null element or to remove one will, however, function 51 * properly. 52 * 53 * <P>Like most collection implementations, {@code EnumSet} is not 54 * synchronized. If multiple threads access an enum set concurrently, and at 55 * least one of the threads modifies the set, it should be synchronized 56 * externally. This is typically accomplished by synchronizing on some 57 * object that naturally encapsulates the enum set. If no such object exists, 58 * the set should be "wrapped" using the {@link Collections#synchronizedSet} 59 * method. This is best done at creation time, to prevent accidental 60 * unsynchronized access: 61 * 62 * <pre> 63 * Set<MyEnum> s = Collections.synchronizedSet(EnumSet.noneOf(MyEnum.class)); 64 * </pre> 65 * 66 * <p>Implementation note: All basic operations execute in constant time. 67 * They are likely (though not guaranteed) to be much faster than their 68 * {@link HashSet} counterparts. Even bulk operations execute in 69 * constant time if their argument is also an enum set. 70 * 71 * <p>This class is a member of the 72 * <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework"> 73 * Java Collections Framework</a>. 74 * 75 * @author Josh Bloch 76 * @since 1.5 77 * @see EnumMap 78 * @serial exclude 79 */ 80@SuppressWarnings("serial") // No serialVersionUID due to usage of 81 // serial proxy pattern 82public abstract class EnumSet<E extends Enum<E>> extends AbstractSet<E> 83 implements Cloneable, java.io.Serializable 84{ 85 /** 86 * The class of all the elements of this set. 87 */ 88 final Class<E> elementType; 89 90 /** 91 * All of the values comprising T. (Cached for performance.) 92 */ 93 final Enum<?>[] universe; 94 95 EnumSet(Class<E>elementType, Enum<?>[] universe) { 96 this.elementType = elementType; 97 this.universe = universe; 98 } 99 100 /** 101 * Creates an empty enum set with the specified element type. 102 * 103 * @param <E> The class of the elements in the set 104 * @param elementType the class object of the element type for this enum 105 * set 106 * @return An empty enum set of the specified type. 107 * @throws NullPointerException if {@code elementType} is null 108 */ 109 public static <E extends Enum<E>> EnumSet<E> noneOf(Class<E> elementType) { 110 Enum<?>[] universe = getUniverse(elementType); 111 if (universe == null) 112 throw new ClassCastException(elementType + " not an enum"); 113 114 if (universe.length <= 64) 115 return new RegularEnumSet<>(elementType, universe); 116 else 117 return new JumboEnumSet<>(elementType, universe); 118 } 119 120 /** 121 * Creates an enum set containing all of the elements in the specified 122 * element type. 123 * 124 * @param <E> The class of the elements in the set 125 * @param elementType the class object of the element type for this enum 126 * set 127 * @return An enum set containing all the elements in the specified type. 128 * @throws NullPointerException if {@code elementType} is null 129 */ 130 public static <E extends Enum<E>> EnumSet<E> allOf(Class<E> elementType) { 131 EnumSet<E> result = noneOf(elementType); 132 result.addAll(); 133 return result; 134 } 135 136 /** 137 * Adds all of the elements from the appropriate enum type to this enum 138 * set, which is empty prior to the call. 139 */ 140 abstract void addAll(); 141 142 /** 143 * Creates an enum set with the same element type as the specified enum 144 * set, initially containing the same elements (if any). 145 * 146 * @param <E> The class of the elements in the set 147 * @param s the enum set from which to initialize this enum set 148 * @return A copy of the specified enum set. 149 * @throws NullPointerException if {@code s} is null 150 */ 151 public static <E extends Enum<E>> EnumSet<E> copyOf(EnumSet<E> s) { 152 return s.clone(); 153 } 154 155 /** 156 * Creates an enum set initialized from the specified collection. If 157 * the specified collection is an {@code EnumSet} instance, this static 158 * factory method behaves identically to {@link #copyOf(EnumSet)}. 159 * Otherwise, the specified collection must contain at least one element 160 * (in order to determine the new enum set's element type). 161 * 162 * @param <E> The class of the elements in the collection 163 * @param c the collection from which to initialize this enum set 164 * @return An enum set initialized from the given collection. 165 * @throws IllegalArgumentException if {@code c} is not an 166 * {@code EnumSet} instance and contains no elements 167 * @throws NullPointerException if {@code c} is null 168 */ 169 public static <E extends Enum<E>> EnumSet<E> copyOf(Collection<E> c) { 170 if (c instanceof EnumSet) { 171 return ((EnumSet<E>)c).clone(); 172 } else { 173 if (c.isEmpty()) 174 throw new IllegalArgumentException("Collection is empty"); 175 Iterator<E> i = c.iterator(); 176 E first = i.next(); 177 EnumSet<E> result = EnumSet.of(first); 178 while (i.hasNext()) 179 result.add(i.next()); 180 return result; 181 } 182 } 183 184 /** 185 * Creates an enum set with the same element type as the specified enum 186 * set, initially containing all the elements of this type that are 187 * <i>not</i> contained in the specified set. 188 * 189 * @param <E> The class of the elements in the enum set 190 * @param s the enum set from whose complement to initialize this enum set 191 * @return The complement of the specified set in this set 192 * @throws NullPointerException if {@code s} is null 193 */ 194 public static <E extends Enum<E>> EnumSet<E> complementOf(EnumSet<E> s) { 195 EnumSet<E> result = copyOf(s); 196 result.complement(); 197 return result; 198 } 199 200 /** 201 * Creates an enum set initially containing the specified element. 202 * 203 * Overloadings of this method exist to initialize an enum set with 204 * one through five elements. A sixth overloading is provided that 205 * uses the varargs feature. This overloading may be used to create 206 * an enum set initially containing an arbitrary number of elements, but 207 * is likely to run slower than the overloadings that do not use varargs. 208 * 209 * @param <E> The class of the specified element and of the set 210 * @param e the element that this set is to contain initially 211 * @throws NullPointerException if {@code e} is null 212 * @return an enum set initially containing the specified element 213 */ 214 public static <E extends Enum<E>> EnumSet<E> of(E e) { 215 EnumSet<E> result = noneOf(e.getDeclaringClass()); 216 result.add(e); 217 return result; 218 } 219 220 /** 221 * Creates an enum set initially containing the specified elements. 222 * 223 * Overloadings of this method exist to initialize an enum set with 224 * one through five elements. A sixth overloading is provided that 225 * uses the varargs feature. This overloading may be used to create 226 * an enum set initially containing an arbitrary number of elements, but 227 * is likely to run slower than the overloadings that do not use varargs. 228 * 229 * @param <E> The class of the parameter elements and of the set 230 * @param e1 an element that this set is to contain initially 231 * @param e2 another element that this set is to contain initially 232 * @throws NullPointerException if any parameters are null 233 * @return an enum set initially containing the specified elements 234 */ 235 public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2) { 236 EnumSet<E> result = noneOf(e1.getDeclaringClass()); 237 result.add(e1); 238 result.add(e2); 239 return result; 240 } 241 242 /** 243 * Creates an enum set initially containing the specified elements. 244 * 245 * Overloadings of this method exist to initialize an enum set with 246 * one through five elements. A sixth overloading is provided that 247 * uses the varargs feature. This overloading may be used to create 248 * an enum set initially containing an arbitrary number of elements, but 249 * is likely to run slower than the overloadings that do not use varargs. 250 * 251 * @param <E> The class of the parameter elements and of the set 252 * @param e1 an element that this set is to contain initially 253 * @param e2 another element that this set is to contain initially 254 * @param e3 another element that this set is to contain initially 255 * @throws NullPointerException if any parameters are null 256 * @return an enum set initially containing the specified elements 257 */ 258 public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3) { 259 EnumSet<E> result = noneOf(e1.getDeclaringClass()); 260 result.add(e1); 261 result.add(e2); 262 result.add(e3); 263 return result; 264 } 265 266 /** 267 * Creates an enum set initially containing the specified elements. 268 * 269 * Overloadings of this method exist to initialize an enum set with 270 * one through five elements. A sixth overloading is provided that 271 * uses the varargs feature. This overloading may be used to create 272 * an enum set initially containing an arbitrary number of elements, but 273 * is likely to run slower than the overloadings that do not use varargs. 274 * 275 * @param <E> The class of the parameter elements and of the set 276 * @param e1 an element that this set is to contain initially 277 * @param e2 another element that this set is to contain initially 278 * @param e3 another element that this set is to contain initially 279 * @param e4 another element that this set is to contain initially 280 * @throws NullPointerException if any parameters are null 281 * @return an enum set initially containing the specified elements 282 */ 283 public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4) { 284 EnumSet<E> result = noneOf(e1.getDeclaringClass()); 285 result.add(e1); 286 result.add(e2); 287 result.add(e3); 288 result.add(e4); 289 return result; 290 } 291 292 /** 293 * Creates an enum set initially containing the specified elements. 294 * 295 * Overloadings of this method exist to initialize an enum set with 296 * one through five elements. A sixth overloading is provided that 297 * uses the varargs feature. This overloading may be used to create 298 * an enum set initially containing an arbitrary number of elements, but 299 * is likely to run slower than the overloadings that do not use varargs. 300 * 301 * @param <E> The class of the parameter elements and of the set 302 * @param e1 an element that this set is to contain initially 303 * @param e2 another element that this set is to contain initially 304 * @param e3 another element that this set is to contain initially 305 * @param e4 another element that this set is to contain initially 306 * @param e5 another element that this set is to contain initially 307 * @throws NullPointerException if any parameters are null 308 * @return an enum set initially containing the specified elements 309 */ 310 public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4, 311 E e5) 312 { 313 EnumSet<E> result = noneOf(e1.getDeclaringClass()); 314 result.add(e1); 315 result.add(e2); 316 result.add(e3); 317 result.add(e4); 318 result.add(e5); 319 return result; 320 } 321 322 /** 323 * Creates an enum set initially containing the specified elements. 324 * This factory, whose parameter list uses the varargs feature, may 325 * be used to create an enum set initially containing an arbitrary 326 * number of elements, but it is likely to run slower than the overloadings 327 * that do not use varargs. 328 * 329 * @param <E> The class of the parameter elements and of the set 330 * @param first an element that the set is to contain initially 331 * @param rest the remaining elements the set is to contain initially 332 * @throws NullPointerException if any of the specified elements are null, 333 * or if {@code rest} is null 334 * @return an enum set initially containing the specified elements 335 */ 336 @SafeVarargs 337 public static <E extends Enum<E>> EnumSet<E> of(E first, E... rest) { 338 EnumSet<E> result = noneOf(first.getDeclaringClass()); 339 result.add(first); 340 for (E e : rest) 341 result.add(e); 342 return result; 343 } 344 345 /** 346 * Creates an enum set initially containing all of the elements in the 347 * range defined by the two specified endpoints. The returned set will 348 * contain the endpoints themselves, which may be identical but must not 349 * be out of order. 350 * 351 * @param <E> The class of the parameter elements and of the set 352 * @param from the first element in the range 353 * @param to the last element in the range 354 * @throws NullPointerException if {@code from} or {@code to} are null 355 * @throws IllegalArgumentException if {@code from.compareTo(to) > 0} 356 * @return an enum set initially containing all of the elements in the 357 * range defined by the two specified endpoints 358 */ 359 public static <E extends Enum<E>> EnumSet<E> range(E from, E to) { 360 if (from.compareTo(to) > 0) 361 throw new IllegalArgumentException(from + " > " + to); 362 EnumSet<E> result = noneOf(from.getDeclaringClass()); 363 result.addRange(from, to); 364 return result; 365 } 366 367 /** 368 * Adds the specified range to this enum set, which is empty prior 369 * to the call. 370 */ 371 abstract void addRange(E from, E to); 372 373 /** 374 * Returns a copy of this set. 375 * 376 * @return a copy of this set 377 */ 378 @SuppressWarnings("unchecked") 379 public EnumSet<E> clone() { 380 try { 381 return (EnumSet<E>) super.clone(); 382 } catch(CloneNotSupportedException e) { 383 throw new AssertionError(e); 384 } 385 } 386 387 /** 388 * Complements the contents of this enum set. 389 */ 390 abstract void complement(); 391 392 /** 393 * Throws an exception if e is not of the correct type for this enum set. 394 */ 395 final void typeCheck(E e) { 396 Class<?> eClass = e.getClass(); 397 if (eClass != elementType && eClass.getSuperclass() != elementType) 398 throw new ClassCastException(eClass + " != " + elementType); 399 } 400 401 /** 402 * Returns all of the values comprising E. 403 * The result is uncloned, cached, and shared by all callers. 404 */ 405 private static <E extends Enum<E>> E[] getUniverse(Class<E> elementType) { 406 return SharedSecrets.getJavaLangAccess() 407 .getEnumConstantsShared(elementType); 408 } 409 410 /** 411 * This class is used to serialize all EnumSet instances, regardless of 412 * implementation type. It captures their "logical contents" and they 413 * are reconstructed using public static factories. This is necessary 414 * to ensure that the existence of a particular implementation type is 415 * an implementation detail. 416 * 417 * @serial include 418 */ 419 private static class SerializationProxy <E extends Enum<E>> 420 implements java.io.Serializable 421 { 422 423 private static final Enum<?>[] ZERO_LENGTH_ENUM_ARRAY = new Enum<?>[0]; 424 425 /** 426 * The element type of this enum set. 427 * 428 * @serial 429 */ 430 private final Class<E> elementType; 431 432 /** 433 * The elements contained in this enum set. 434 * 435 * @serial 436 */ 437 private final Enum<?>[] elements; 438 439 SerializationProxy(EnumSet<E> set) { 440 elementType = set.elementType; 441 elements = set.toArray(ZERO_LENGTH_ENUM_ARRAY); 442 } 443 444 // instead of cast to E, we should perhaps use elementType.cast() 445 // to avoid injection of forged stream, but it will slow the implementation 446 @SuppressWarnings("unchecked") 447 private Object readResolve() { 448 EnumSet<E> result = EnumSet.noneOf(elementType); 449 for (Enum<?> e : elements) 450 result.add((E)e); 451 return result; 452 } 453 454 private static final long serialVersionUID = 362491234563181265L; 455 } 456 457 Object writeReplace() { 458 return new SerializationProxy<>(this); 459 } 460 461 // readObject method for the serialization proxy pattern 462 // See Effective Java, Second Ed., Item 78. 463 private void readObject(java.io.ObjectInputStream stream) 464 throws java.io.InvalidObjectException { 465 throw new java.io.InvalidObjectException("Proxy required"); 466 } 467} 468