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| 1 | /* | ||
| 2 | * Copyright (c) 1998, 2010, 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.util; | ||
| 27 | |||
| 28 | /** | ||
| 29 | * A {@link NavigableSet} implementation based on a {@link TreeMap}. | ||
| 30 | * The elements are ordered using their {@linkplain Comparable natural | ||
| 31 | * ordering}, or by a {@link Comparator} provided at set creation | ||
| 32 | * time, depending on which constructor is used. | ||
| 33 | * | ||
| 34 | * <p>This implementation provides guaranteed log(n) time cost for the basic | ||
| 35 | * operations ({@code add}, {@code remove} and {@code contains}). | ||
| 36 | * | ||
| 37 | * <p>Note that the ordering maintained by a set (whether or not an explicit | ||
| 38 | * comparator is provided) must be <i>consistent with equals</i> if it is to | ||
| 39 | * correctly implement the {@code Set} interface. (See {@code Comparable} | ||
| 40 | * or {@code Comparator} for a precise definition of <i>consistent with | ||
| 41 | * equals</i>.) This is so because the {@code Set} interface is defined in | ||
| 42 | * terms of the {@code equals} operation, but a {@code TreeSet} instance | ||
| 43 | * performs all element comparisons using its {@code compareTo} (or | ||
| 44 | * {@code compare}) method, so two elements that are deemed equal by this method | ||
| 45 | * are, from the standpoint of the set, equal. The behavior of a set | ||
| 46 | * <i>is</i> well-defined even if its ordering is inconsistent with equals; it | ||
| 47 | * just fails to obey the general contract of the {@code Set} interface. | ||
| 48 | * | ||
| 49 | * <p><strong>Note that this implementation is not synchronized.</strong> | ||
| 50 | * If multiple threads access a tree set concurrently, and at least one | ||
| 51 | * of the threads modifies the set, it <i>must</i> be synchronized | ||
| 52 | * externally. This is typically accomplished by synchronizing on some | ||
| 53 | * object that naturally encapsulates the set. | ||
| 54 | * If no such object exists, the set should be "wrapped" using the | ||
| 55 | * {@link Collections#synchronizedSortedSet Collections.synchronizedSortedSet} | ||
| 56 | * method. This is best done at creation time, to prevent accidental | ||
| 57 | * unsynchronized access to the set: <pre> | ||
| 58 | * SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...));</pre> | ||
| 59 | * | ||
| 60 | * <p>The iterators returned by this class's {@code iterator} method are | ||
| 61 | * <i>fail-fast</i>: if the set is modified at any time after the iterator is | ||
| 62 | * created, in any way except through the iterator's own {@code remove} | ||
| 63 | * method, the iterator will throw a {@link ConcurrentModificationException}. | ||
| 64 | * Thus, in the face of concurrent modification, the iterator fails quickly | ||
| 65 | * and cleanly, rather than risking arbitrary, non-deterministic behavior at | ||
| 66 | * an undetermined time in the future. | ||
| 67 | * | ||
| 68 | * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed | ||
| 69 | * as it is, generally speaking, impossible to make any hard guarantees in the | ||
| 70 | * presence of unsynchronized concurrent modification. Fail-fast iterators | ||
| 71 | * throw {@code ConcurrentModificationException} on a best-effort basis. | ||
| 72 | * Therefore, it would be wrong to write a program that depended on this | ||
| 73 | * exception for its correctness: <i>the fail-fast behavior of iterators | ||
| 74 | * should be used only to detect bugs.</i> | ||
| 75 | * | ||
| 76 | * <p>This class is a member of the | ||
| 77 | * <a href="{@docRoot}/../technotes/guides/collections/index.html"> | ||
| 78 | * Java Collections Framework</a>. | ||
| 79 | * | ||
| 80 | * @param <E> the type of elements maintained by this set | ||
| 81 | * | ||
| 82 | * @author Josh Bloch | ||
| 83 | * @see Collection | ||
| 84 | * @see Set | ||
| 85 | * @see HashSet | ||
| 86 | * @see Comparable | ||
| 87 | * @see Comparator | ||
| 88 | * @see TreeMap | ||
| 89 | * @since 1.2 | ||
| 90 | */ | ||
| 91 | |||
| 92 | public class TreeSet<E> extends AbstractSet<E> | ||
| 93 | implements NavigableSet<E>, Cloneable, java.io.Serializable | ||
| 94 | { | ||
| 95 | /** | ||
| 96 | * The backing map. | ||
| 97 | */ | ||
| 98 | private transient NavigableMap<E,Object> m; | ||
| 99 | |||
| 100 | // Dummy value to associate with an Object in the backing Map | ||
| 101 | private static final Object PRESENT = new Object(); | ||
| 102 | |||
| 103 | /** | ||
| 104 | * Constructs a set backed by the specified navigable map. | ||
| 105 | */ | ||
| 106 | TreeSet(NavigableMap<E,Object> m) { | ||
| 107 | this.m = m; | ||
| 108 | } | ||
| 109 | |||
| 110 | /** | ||
| 111 | * Constructs a new, empty tree set, sorted according to the | ||
| 112 | * natural ordering of its elements. All elements inserted into | ||
| 113 | * the set must implement the {@link Comparable} interface. | ||
| 114 | * Furthermore, all such elements must be <i>mutually | ||
| 115 | * comparable</i>: {@code e1.compareTo(e2)} must not throw a | ||
| 116 | * {@code ClassCastException} for any elements {@code e1} and | ||
| 117 | * {@code e2} in the set. If the user attempts to add an element | ||
| 118 | * to the set that violates this constraint (for example, the user | ||
| 119 | * attempts to add a string element to a set whose elements are | ||
| 120 | * integers), the {@code add} call will throw a | ||
| 121 | * {@code ClassCastException}. | ||
| 122 | */ | ||
| 123 | public TreeSet() { | ||
| 124 | this(new TreeMap<E,Object>()); | ||
| 125 | } | ||
| 126 | |||
| 127 | /** | ||
| 128 | * Constructs a new, empty tree set, sorted according to the specified | ||
| 129 | * comparator. All elements inserted into the set must be <i>mutually | ||
| 130 | * comparable</i> by the specified comparator: {@code comparator.compare(e1, | ||
| 131 | * e2)} must not throw a {@code ClassCastException} for any elements | ||
| 132 | * {@code e1} and {@code e2} in the set. If the user attempts to add | ||
| 133 | * an element to the set that violates this constraint, the | ||
| 134 | * {@code add} call will throw a {@code ClassCastException}. | ||
| 135 | * | ||
| 136 | * @param comparator the comparator that will be used to order this set. | ||
| 137 | * If {@code null}, the {@linkplain Comparable natural | ||
| 138 | * ordering} of the elements will be used. | ||
| 139 | */ | ||
| 140 | public TreeSet(Comparator<? super E> comparator) { | ||
| 141 | this(new TreeMap<>(comparator)); | ||
| 142 | } | ||
| 143 | |||
| 144 | /** | ||
| 145 | * Constructs a new tree set containing the elements in the specified | ||
| 146 | * collection, sorted according to the <i>natural ordering</i> of its | ||
| 147 | * elements. All elements inserted into the set must implement the | ||
| 148 | * {@link Comparable} interface. Furthermore, all such elements must be | ||
| 149 | * <i>mutually comparable</i>: {@code e1.compareTo(e2)} must not throw a | ||
| 150 | * {@code ClassCastException} for any elements {@code e1} and | ||
| 151 | * {@code e2} in the set. | ||
| 152 | * | ||
| 153 | * @param c collection whose elements will comprise the new set | ||
| 154 | * @throws ClassCastException if the elements in {@code c} are | ||
| 155 | * not {@link Comparable}, or are not mutually comparable | ||
| 156 | * @throws NullPointerException if the specified collection is null | ||
| 157 | */ | ||
| 158 | public TreeSet(Collection<? extends E> c) { | ||
| 159 | this(); | ||
| 160 | addAll(c); | ||
| 161 | } | ||
| 162 | |||
| 163 | /** | ||
| 164 | * Constructs a new tree set containing the same elements and | ||
| 165 | * using the same ordering as the specified sorted set. | ||
| 166 | * | ||
| 167 | * @param s sorted set whose elements will comprise the new set | ||
| 168 | * @throws NullPointerException if the specified sorted set is null | ||
| 169 | */ | ||
| 170 | public TreeSet(SortedSet<E> s) { | ||
| 171 | this(s.comparator()); | ||
| 172 | addAll(s); | ||
| 173 | } | ||
| 174 | |||
| 175 | /** | ||
| 176 | * Returns an iterator over the elements in this set in ascending order. | ||
| 177 | * | ||
| 178 | * @return an iterator over the elements in this set in ascending order | ||
| 179 | */ | ||
| 180 | public Iterator<E> iterator() { | ||
| 181 | return m.navigableKeySet().iterator(); | ||
| 182 | } | ||
| 183 | |||
| 184 | /** | ||
| 185 | * Returns an iterator over the elements in this set in descending order. | ||
| 186 | * | ||
| 187 | * @return an iterator over the elements in this set in descending order | ||
| 188 | * @since 1.6 | ||
| 189 | */ | ||
| 190 | public Iterator<E> descendingIterator() { | ||
| 191 | return m.descendingKeySet().iterator(); | ||
| 192 | } | ||
| 193 | |||
| 194 | /** | ||
| 195 | * @since 1.6 | ||
| 196 | */ | ||
| 197 | public NavigableSet<E> descendingSet() { | ||
| 198 | return new TreeSet<>(m.descendingMap()); | ||
| 199 | } | ||
| 200 | |||
| 201 | /** | ||
| 202 | * Returns the number of elements in this set (its cardinality). | ||
| 203 | * | ||
| 204 | * @return the number of elements in this set (its cardinality) | ||
| 205 | */ | ||
| 206 | public int size() { | ||
| 207 | return m.size(); | ||
| 208 | } | ||
| 209 | |||
| 210 | /** | ||
| 211 | * Returns {@code true} if this set contains no elements. | ||
| 212 | * | ||
| 213 | * @return {@code true} if this set contains no elements | ||
| 214 | */ | ||
| 215 | public boolean isEmpty() { | ||
| 216 | return m.isEmpty(); | ||
| 217 | } | ||
| 218 | |||
| 219 | /** | ||
| 220 | * Returns {@code true} if this set contains the specified element. | ||
| 221 | * More formally, returns {@code true} if and only if this set | ||
| 222 | * contains an element {@code e} such that | ||
| 223 | * <tt>(o==null ? e==null : o.equals(e))</tt>. | ||
| 224 | * | ||
| 225 | * @param o object to be checked for containment in this set | ||
| 226 | * @return {@code true} if this set contains the specified element | ||
| 227 | * @throws ClassCastException if the specified object cannot be compared | ||
| 228 | * with the elements currently in the set | ||
| 229 | * @throws NullPointerException if the specified element is null | ||
| 230 | * and this set uses natural ordering, or its comparator | ||
| 231 | * does not permit null elements | ||
| 232 | */ | ||
| 233 | public boolean contains(Object o) { | ||
| 234 | return m.containsKey(o); | ||
| 235 | } | ||
| 236 | |||
| 237 | /** | ||
| 238 | * Adds the specified element to this set if it is not already present. | ||
| 239 | * More formally, adds the specified element {@code e} to this set if | ||
| 240 | * the set contains no element {@code e2} such that | ||
| 241 | * <tt>(e==null ? e2==null : e.equals(e2))</tt>. | ||
| 242 | * If this set already contains the element, the call leaves the set | ||
| 243 | * unchanged and returns {@code false}. | ||
| 244 | * | ||
| 245 | * @param e element to be added to this set | ||
| 246 | * @return {@code true} if this set did not already contain the specified | ||
| 247 | * element | ||
| 248 | * @throws ClassCastException if the specified object cannot be compared | ||
| 249 | * with the elements currently in this set | ||
| 250 | * @throws NullPointerException if the specified element is null | ||
| 251 | * and this set uses natural ordering, or its comparator | ||
| 252 | * does not permit null elements | ||
| 253 | */ | ||
| 254 | public boolean add(E e) { | ||
| 255 | return m.put(e, PRESENT)==null; | ||
| 256 | } | ||
| 257 | |||
| 258 | /** | ||
| 259 | * Removes the specified element from this set if it is present. | ||
| 260 | * More formally, removes an element {@code e} such that | ||
| 261 | * <tt>(o==null ? e==null : o.equals(e))</tt>, | ||
| 262 | * if this set contains such an element. Returns {@code true} if | ||
| 263 | * this set contained the element (or equivalently, if this set | ||
| 264 | * changed as a result of the call). (This set will not contain the | ||
| 265 | * element once the call returns.) | ||
| 266 | * | ||
| 267 | * @param o object to be removed from this set, if present | ||
| 268 | * @return {@code true} if this set contained the specified element | ||
| 269 | * @throws ClassCastException if the specified object cannot be compared | ||
| 270 | * with the elements currently in this set | ||
| 271 | * @throws NullPointerException if the specified element is null | ||
| 272 | * and this set uses natural ordering, or its comparator | ||
| 273 | * does not permit null elements | ||
| 274 | */ | ||
| 275 | public boolean remove(Object o) { | ||
| 276 | return m.remove(o)==PRESENT; | ||
| 277 | } | ||
| 278 | |||
| 279 | /** | ||
| 280 | * Removes all of the elements from this set. | ||
| 281 | * The set will be empty after this call returns. | ||
| 282 | */ | ||
| 283 | public void clear() { | ||
| 284 | m.clear(); | ||
| 285 | } | ||
| 286 | |||
| 287 | /** | ||
| 288 | * Adds all of the elements in the specified collection to this set. | ||
| 289 | * | ||
| 290 | * @param c collection containing elements to be added to this set | ||
| 291 | * @return {@code true} if this set changed as a result of the call | ||
| 292 | * @throws ClassCastException if the elements provided cannot be compared | ||
| 293 | * with the elements currently in the set | ||
| 294 | * @throws NullPointerException if the specified collection is null or | ||
| 295 | * if any element is null and this set uses natural ordering, or | ||
| 296 | * its comparator does not permit null elements | ||
| 297 | */ | ||
| 298 | public boolean addAll(Collection<? extends E> c) { | ||
| 299 | // Use linear-time version if applicable | ||
| 300 | if (m.size()==0 && c.size() > 0 && | ||
| 301 | c instanceof SortedSet && | ||
| 302 | m instanceof TreeMap) { | ||
| 303 | SortedSet<? extends E> set = (SortedSet<? extends E>) c; | ||
| 304 | TreeMap<E,Object> map = (TreeMap<E, Object>) m; | ||
| 305 | Comparator<? super E> cc = (Comparator<? super E>) set.comparator(); | ||
| 306 | Comparator<? super E> mc = map.comparator(); | ||
| 307 | if (cc==mc || (cc != null && cc.equals(mc))) { | ||
| 308 | map.addAllForTreeSet(set, PRESENT); | ||
| 309 | return true; | ||
| 310 | } | ||
| 311 | } | ||
| 312 | return super.addAll(c); | ||
| 313 | } | ||
| 314 | |||
| 315 | /** | ||
| 316 | * @throws ClassCastException {@inheritDoc} | ||
| 317 | * @throws NullPointerException if {@code fromElement} or {@code toElement} | ||
| 318 | * is null and this set uses natural ordering, or its comparator | ||
| 319 | * does not permit null elements | ||
| 320 | * @throws IllegalArgumentException {@inheritDoc} | ||
| 321 | * @since 1.6 | ||
| 322 | */ | ||
| 323 | public NavigableSet<E> subSet(E fromElement, boolean fromInclusive, | ||
| 324 | E toElement, boolean toInclusive) { | ||
| 325 | return new TreeSet<>(m.subMap(fromElement, fromInclusive, | ||
| 326 | toElement, toInclusive)); | ||
| 327 | } | ||
| 328 | |||
| 329 | /** | ||
| 330 | * @throws ClassCastException {@inheritDoc} | ||
| 331 | * @throws NullPointerException if {@code toElement} is null and | ||
| 332 | * this set uses natural ordering, or its comparator does | ||
| 333 | * not permit null elements | ||
| 334 | * @throws IllegalArgumentException {@inheritDoc} | ||
| 335 | * @since 1.6 | ||
| 336 | */ | ||
| 337 | public NavigableSet<E> headSet(E toElement, boolean inclusive) { | ||
| 338 | return new TreeSet<>(m.headMap(toElement, inclusive)); | ||
| 339 | } | ||
| 340 | |||
| 341 | /** | ||
| 342 | * @throws ClassCastException {@inheritDoc} | ||
| 343 | * @throws NullPointerException if {@code fromElement} is null and | ||
| 344 | * this set uses natural ordering, or its comparator does | ||
| 345 | * not permit null elements | ||
| 346 | * @throws IllegalArgumentException {@inheritDoc} | ||
| 347 | * @since 1.6 | ||
| 348 | */ | ||
| 349 | public NavigableSet<E> tailSet(E fromElement, boolean inclusive) { | ||
| 350 | return new TreeSet<>(m.tailMap(fromElement, inclusive)); | ||
| 351 | } | ||
| 352 | |||
| 353 | /** | ||
| 354 | * @throws ClassCastException {@inheritDoc} | ||
| 355 | * @throws NullPointerException if {@code fromElement} or | ||
| 356 | * {@code toElement} is null and this set uses natural ordering, | ||
| 357 | * or its comparator does not permit null elements | ||
| 358 | * @throws IllegalArgumentException {@inheritDoc} | ||
| 359 | */ | ||
| 360 | public SortedSet<E> subSet(E fromElement, E toElement) { | ||
| 361 | return subSet(fromElement, true, toElement, false); | ||
| 362 | } | ||
| 363 | |||
| 364 | /** | ||
| 365 | * @throws ClassCastException {@inheritDoc} | ||
| 366 | * @throws NullPointerException if {@code toElement} is null | ||
| 367 | * and this set uses natural ordering, or its comparator does | ||
| 368 | * not permit null elements | ||
| 369 | * @throws IllegalArgumentException {@inheritDoc} | ||
| 370 | */ | ||
| 371 | public SortedSet<E> headSet(E toElement) { | ||
| 372 | return headSet(toElement, false); | ||
| 373 | } | ||
| 374 | |||
| 375 | /** | ||
| 376 | * @throws ClassCastException {@inheritDoc} | ||
| 377 | * @throws NullPointerException if {@code fromElement} is null | ||
| 378 | * and this set uses natural ordering, or its comparator does | ||
| 379 | * not permit null elements | ||
| 380 | * @throws IllegalArgumentException {@inheritDoc} | ||
| 381 | */ | ||
| 382 | public SortedSet<E> tailSet(E fromElement) { | ||
| 383 | return tailSet(fromElement, true); | ||
| 384 | } | ||
| 385 | |||
| 386 | public Comparator<? super E> comparator() { | ||
| 387 | return m.comparator(); | ||
| 388 | } | ||
| 389 | |||
| 390 | /** | ||
| 391 | * @throws NoSuchElementException {@inheritDoc} | ||
| 392 | */ | ||
| 393 | public E first() { | ||
| 394 | return m.firstKey(); | ||
| 395 | } | ||
| 396 | |||
| 397 | /** | ||
| 398 | * @throws NoSuchElementException {@inheritDoc} | ||
| 399 | */ | ||
| 400 | public E last() { | ||
| 401 | return m.lastKey(); | ||
| 402 | } | ||
| 403 | |||
| 404 | // NavigableSet API methods | ||
| 405 | |||
| 406 | /** | ||
| 407 | * @throws ClassCastException {@inheritDoc} | ||
| 408 | * @throws NullPointerException if the specified element is null | ||
| 409 | * and this set uses natural ordering, or its comparator | ||
| 410 | * does not permit null elements | ||
| 411 | * @since 1.6 | ||
| 412 | */ | ||
| 413 | public E lower(E e) { | ||
| 414 | return m.lowerKey(e); | ||
| 415 | } | ||
| 416 | |||
| 417 | /** | ||
| 418 | * @throws ClassCastException {@inheritDoc} | ||
| 419 | * @throws NullPointerException if the specified element is null | ||
| 420 | * and this set uses natural ordering, or its comparator | ||
| 421 | * does not permit null elements | ||
| 422 | * @since 1.6 | ||
| 423 | */ | ||
| 424 | public E floor(E e) { | ||
| 425 | return m.floorKey(e); | ||
| 426 | } | ||
| 427 | |||
| 428 | /** | ||
| 429 | * @throws ClassCastException {@inheritDoc} | ||
| 430 | * @throws NullPointerException if the specified element is null | ||
| 431 | * and this set uses natural ordering, or its comparator | ||
| 432 | * does not permit null elements | ||
| 433 | * @since 1.6 | ||
| 434 | */ | ||
| 435 | public E ceiling(E e) { | ||
| 436 | return m.ceilingKey(e); | ||
| 437 | } | ||
| 438 | |||
| 439 | /** | ||
| 440 | * @throws ClassCastException {@inheritDoc} | ||
| 441 | * @throws NullPointerException if the specified element is null | ||
| 442 | * and this set uses natural ordering, or its comparator | ||
| 443 | * does not permit null elements | ||
| 444 | * @since 1.6 | ||
| 445 | */ | ||
| 446 | public E higher(E e) { | ||
| 447 | return m.higherKey(e); | ||
| 448 | } | ||
| 449 | |||
| 450 | /** | ||
| 451 | * @since 1.6 | ||
| 452 | */ | ||
| 453 | public E pollFirst() { | ||
| 454 | Map.Entry<E,?> e = m.pollFirstEntry(); | ||
| 455 | return (e == null) ? null : e.getKey(); | ||
| 456 | } | ||
| 457 | |||
| 458 | /** | ||
| 459 | * @since 1.6 | ||
| 460 | */ | ||
| 461 | public E pollLast() { | ||
| 462 | Map.Entry<E,?> e = m.pollLastEntry(); | ||
| 463 | return (e == null) ? null : e.getKey(); | ||
| 464 | } | ||
| 465 | |||
| 466 | /** | ||
| 467 | * Returns a shallow copy of this {@code TreeSet} instance. (The elements | ||
| 468 | * themselves are not cloned.) | ||
| 469 | * | ||
| 470 | * @return a shallow copy of this set | ||
| 471 | */ | ||
| 472 | public Object clone() { | ||
| 473 | TreeSet<E> clone = null; | ||
| 474 | try { | ||
| 475 | clone = (TreeSet<E>) super.clone(); | ||
| 476 | } catch (CloneNotSupportedException e) { | ||
| 477 | throw new InternalError(); | ||
| 478 | } | ||
| 479 | |||
| 480 | clone.m = new TreeMap<>(m); | ||
| 481 | return clone; | ||
| 482 | } | ||
| 483 | |||
| 484 | /** | ||
| 485 | * Save the state of the {@code TreeSet} instance to a stream (that is, | ||
| 486 | * serialize it). | ||
| 487 | * | ||
| 488 | * @serialData Emits the comparator used to order this set, or | ||
| 489 | * {@code null} if it obeys its elements' natural ordering | ||
| 490 | * (Object), followed by the size of the set (the number of | ||
| 491 | * elements it contains) (int), followed by all of its | ||
| 492 | * elements (each an Object) in order (as determined by the | ||
| 493 | * set's Comparator, or by the elements' natural ordering if | ||
| 494 | * the set has no Comparator). | ||
| 495 | */ | ||
| 496 | private void writeObject(java.io.ObjectOutputStream s) | ||
| 497 | throws java.io.IOException { | ||
| 498 | // Write out any hidden stuff | ||
| 499 | s.defaultWriteObject(); | ||
| 500 | |||
| 501 | // Write out Comparator | ||
| 502 | s.writeObject(m.comparator()); | ||
| 503 | |||
| 504 | // Write out size | ||
| 505 | s.writeInt(m.size()); | ||
| 506 | |||
| 507 | // Write out all elements in the proper order. | ||
| 508 | for (E e : m.keySet()) | ||
| 509 | s.writeObject(e); | ||
| 510 | } | ||
| 511 | |||
| 512 | /** | ||
| 513 | * Reconstitute the {@code TreeSet} instance from a stream (that is, | ||
| 514 | * deserialize it). | ||
| 515 | */ | ||
| 516 | private void readObject(java.io.ObjectInputStream s) | ||
| 517 | throws java.io.IOException, ClassNotFoundException { | ||
| 518 | // Read in any hidden stuff | ||
| 519 | s.defaultReadObject(); | ||
| 520 | |||
| 521 | // Read in Comparator | ||
| 522 | Comparator<? super E> c = (Comparator<? super E>) s.readObject(); | ||
| 523 | |||
| 524 | // Create backing TreeMap | ||
| 525 | TreeMap<E,Object> tm; | ||
| 526 | if (c==null) | ||
| 527 | tm = new TreeMap<>(); | ||
| 528 | else | ||
| 529 | tm = new TreeMap<>(c); | ||
| 530 | m = tm; | ||
| 531 | |||
| 532 | // Read in size | ||
| 533 | int size = s.readInt(); | ||
| 534 | |||
| 535 | tm.readTreeSet(size, s, PRESENT); | ||
| 536 | } | ||
| 537 | |||
| 538 | private static final long serialVersionUID = -2479143000061671589L; | ||
| 539 | } | ||