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--- old/src/share/classes/java/util/TreeSet.java
+++ new/src/share/classes/java/util/TreeSet.java
1 1 /*
2 2 * Copyright (c) 1998, 2008, Oracle and/or its affiliates. All rights reserved.
3 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 4 *
5 5 * This code is free software; you can redistribute it and/or modify it
6 6 * under the terms of the GNU General Public License version 2 only, as
7 7 * published by the Free Software Foundation. Oracle designates this
8 8 * particular file as subject to the "Classpath" exception as provided
9 9 * by Oracle in the LICENSE file that accompanied this code.
10 10 *
11 11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 14 * version 2 for more details (a copy is included in the LICENSE file that
15 15 * accompanied this code).
16 16 *
17 17 * You should have received a copy of the GNU General Public License version
18 18 * 2 along with this work; if not, write to the Free Software Foundation,
19 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 20 *
21 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 22 * or visit www.oracle.com if you need additional information or have any
23 23 * questions.
24 24 */
25 25
26 26 package java.util;
27 27
28 28 /**
29 29 * A {@link NavigableSet} implementation based on a {@link TreeMap}.
30 30 * The elements are ordered using their {@linkplain Comparable natural
31 31 * ordering}, or by a {@link Comparator} provided at set creation
32 32 * time, depending on which constructor is used.
33 33 *
34 34 * <p>This implementation provides guaranteed log(n) time cost for the basic
35 35 * operations ({@code add}, {@code remove} and {@code contains}).
36 36 *
37 37 * <p>Note that the ordering maintained by a set (whether or not an explicit
38 38 * comparator is provided) must be <i>consistent with equals</i> if it is to
39 39 * correctly implement the {@code Set} interface. (See {@code Comparable}
40 40 * or {@code Comparator} for a precise definition of <i>consistent with
41 41 * equals</i>.) This is so because the {@code Set} interface is defined in
42 42 * terms of the {@code equals} operation, but a {@code TreeSet} instance
43 43 * performs all element comparisons using its {@code compareTo} (or
44 44 * {@code compare}) method, so two elements that are deemed equal by this method
45 45 * are, from the standpoint of the set, equal. The behavior of a set
46 46 * <i>is</i> well-defined even if its ordering is inconsistent with equals; it
47 47 * just fails to obey the general contract of the {@code Set} interface.
48 48 *
49 49 * <p><strong>Note that this implementation is not synchronized.</strong>
50 50 * If multiple threads access a tree set concurrently, and at least one
51 51 * of the threads modifies the set, it <i>must</i> be synchronized
52 52 * externally. This is typically accomplished by synchronizing on some
53 53 * object that naturally encapsulates the set.
54 54 * If no such object exists, the set should be "wrapped" using the
55 55 * {@link Collections#synchronizedSortedSet Collections.synchronizedSortedSet}
56 56 * method. This is best done at creation time, to prevent accidental
57 57 * unsynchronized access to the set: <pre>
58 58 * SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...));</pre>
59 59 *
60 60 * <p>The iterators returned by this class's {@code iterator} method are
61 61 * <i>fail-fast</i>: if the set is modified at any time after the iterator is
62 62 * created, in any way except through the iterator's own {@code remove}
63 63 * method, the iterator will throw a {@link ConcurrentModificationException}.
64 64 * Thus, in the face of concurrent modification, the iterator fails quickly
65 65 * and cleanly, rather than risking arbitrary, non-deterministic behavior at
66 66 * an undetermined time in the future.
67 67 *
68 68 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
69 69 * as it is, generally speaking, impossible to make any hard guarantees in the
70 70 * presence of unsynchronized concurrent modification. Fail-fast iterators
71 71 * throw {@code ConcurrentModificationException} on a best-effort basis.
72 72 * Therefore, it would be wrong to write a program that depended on this
73 73 * exception for its correctness: <i>the fail-fast behavior of iterators
74 74 * should be used only to detect bugs.</i>
75 75 *
76 76 * <p>This class is a member of the
77 77 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
78 78 * Java Collections Framework</a>.
79 79 *
80 80 * @param <E> the type of elements maintained by this set
81 81 *
82 82 * @author Josh Bloch
83 83 * @see Collection
84 84 * @see Set
85 85 * @see HashSet
86 86 * @see Comparable
87 87 * @see Comparator
88 88 * @see TreeMap
89 89 * @since 1.2
90 90 */
91 91
92 92 public class TreeSet<E> extends AbstractSet<E>
93 93 implements NavigableSet<E>, Cloneable, java.io.Serializable
94 94 {
95 95 /**
96 96 * The backing map.
97 97 */
98 98 private transient NavigableMap<E,Object> m;
99 99
100 100 // Dummy value to associate with an Object in the backing Map
101 101 private static final Object PRESENT = new Object();
102 102
103 103 /**
104 104 * Constructs a set backed by the specified navigable map.
105 105 */
106 106 TreeSet(NavigableMap<E,Object> m) {
107 107 this.m = m;
108 108 }
109 109
110 110 /**
111 111 * Constructs a new, empty tree set, sorted according to the
112 112 * natural ordering of its elements. All elements inserted into
113 113 * the set must implement the {@link Comparable} interface.
114 114 * Furthermore, all such elements must be <i>mutually
115 115 * comparable</i>: {@code e1.compareTo(e2)} must not throw a
116 116 * {@code ClassCastException} for any elements {@code e1} and
117 117 * {@code e2} in the set. If the user attempts to add an element
118 118 * to the set that violates this constraint (for example, the user
119 119 * attempts to add a string element to a set whose elements are
120 120 * integers), the {@code add} call will throw a
121 121 * {@code ClassCastException}.
122 122 */
123 123 public TreeSet() {
124 124 this(new TreeMap<E,Object>());
125 125 }
126 126
127 127 /**
128 128 * Constructs a new, empty tree set, sorted according to the specified
129 129 * comparator. All elements inserted into the set must be <i>mutually
130 130 * comparable</i> by the specified comparator: {@code comparator.compare(e1,
131 131 * e2)} must not throw a {@code ClassCastException} for any elements
132 132 * {@code e1} and {@code e2} in the set. If the user attempts to add
133 133 * an element to the set that violates this constraint, the
134 134 * {@code add} call will throw a {@code ClassCastException}.
135 135 *
136 136 * @param comparator the comparator that will be used to order this set.
137 137 * If {@code null}, the {@linkplain Comparable natural
138 138 * ordering} of the elements will be used.
139 139 */
140 140 public TreeSet(Comparator<? super E> comparator) {
141 141 this(new TreeMap<E,Object>(comparator));
142 142 }
143 143
144 144 /**
145 145 * Constructs a new tree set containing the elements in the specified
146 146 * collection, sorted according to the <i>natural ordering</i> of its
147 147 * elements. All elements inserted into the set must implement the
148 148 * {@link Comparable} interface. Furthermore, all such elements must be
149 149 * <i>mutually comparable</i>: {@code e1.compareTo(e2)} must not throw a
150 150 * {@code ClassCastException} for any elements {@code e1} and
151 151 * {@code e2} in the set.
152 152 *
153 153 * @param c collection whose elements will comprise the new set
154 154 * @throws ClassCastException if the elements in {@code c} are
155 155 * not {@link Comparable}, or are not mutually comparable
156 156 * @throws NullPointerException if the specified collection is null
157 157 */
158 158 public TreeSet(Collection<? extends E> c) {
159 159 this();
160 160 addAll(c);
161 161 }
162 162
163 163 /**
164 164 * Constructs a new tree set containing the same elements and
165 165 * using the same ordering as the specified sorted set.
166 166 *
167 167 * @param s sorted set whose elements will comprise the new set
168 168 * @throws NullPointerException if the specified sorted set is null
169 169 */
170 170 public TreeSet(SortedSet<E> s) {
171 171 this(s.comparator());
172 172 addAll(s);
173 173 }
174 174
175 175 /**
176 176 * Returns an iterator over the elements in this set in ascending order.
177 177 *
178 178 * @return an iterator over the elements in this set in ascending order
179 179 */
180 180 public Iterator<E> iterator() {
181 181 return m.navigableKeySet().iterator();
182 182 }
183 183
184 184 /**
185 185 * Returns an iterator over the elements in this set in descending order.
186 186 *
187 187 * @return an iterator over the elements in this set in descending order
188 188 * @since 1.6
189 189 */
190 190 public Iterator<E> descendingIterator() {
191 191 return m.descendingKeySet().iterator();
192 192 }
193 193
194 194 /**
195 195 * @since 1.6
196 196 */
197 197 public NavigableSet<E> descendingSet() {
198 198 return new TreeSet<E>(m.descendingMap());
199 199 }
200 200
201 201 /**
202 202 * Returns the number of elements in this set (its cardinality).
203 203 *
204 204 * @return the number of elements in this set (its cardinality)
205 205 */
206 206 public int size() {
207 207 return m.size();
208 208 }
209 209
210 210 /**
211 211 * Returns {@code true} if this set contains no elements.
212 212 *
213 213 * @return {@code true} if this set contains no elements
214 214 */
215 215 public boolean isEmpty() {
216 216 return m.isEmpty();
217 217 }
218 218
219 219 /**
220 220 * Returns {@code true} if this set contains the specified element.
221 221 * More formally, returns {@code true} if and only if this set
222 222 * contains an element {@code e} such that
223 223 * <tt>(o==null ? e==null : o.equals(e))</tt>.
224 224 *
225 225 * @param o object to be checked for containment in this set
226 226 * @return {@code true} if this set contains the specified element
227 227 * @throws ClassCastException if the specified object cannot be compared
228 228 * with the elements currently in the set
229 229 * @throws NullPointerException if the specified element is null
230 230 * and this set uses natural ordering, or its comparator
231 231 * does not permit null elements
232 232 */
233 233 public boolean contains(Object o) {
234 234 return m.containsKey(o);
235 235 }
236 236
237 237 /**
238 238 * Adds the specified element to this set if it is not already present.
239 239 * More formally, adds the specified element {@code e} to this set if
240 240 * the set contains no element {@code e2} such that
241 241 * <tt>(e==null ? e2==null : e.equals(e2))</tt>.
242 242 * If this set already contains the element, the call leaves the set
243 243 * unchanged and returns {@code false}.
244 244 *
245 245 * @param e element to be added to this set
246 246 * @return {@code true} if this set did not already contain the specified
247 247 * element
248 248 * @throws ClassCastException if the specified object cannot be compared
249 249 * with the elements currently in this set
250 250 * @throws NullPointerException if the specified element is null
251 251 * and this set uses natural ordering, or its comparator
252 252 * does not permit null elements
253 253 */
254 254 public boolean add(E e) {
255 255 return m.put(e, PRESENT)==null;
256 256 }
257 257
258 258 /**
259 259 * Removes the specified element from this set if it is present.
260 260 * More formally, removes an element {@code e} such that
261 261 * <tt>(o==null ? e==null : o.equals(e))</tt>,
262 262 * if this set contains such an element. Returns {@code true} if
263 263 * this set contained the element (or equivalently, if this set
264 264 * changed as a result of the call). (This set will not contain the
265 265 * element once the call returns.)
266 266 *
267 267 * @param o object to be removed from this set, if present
268 268 * @return {@code true} if this set contained the specified element
269 269 * @throws ClassCastException if the specified object cannot be compared
270 270 * with the elements currently in this set
271 271 * @throws NullPointerException if the specified element is null
272 272 * and this set uses natural ordering, or its comparator
273 273 * does not permit null elements
274 274 */
275 275 public boolean remove(Object o) {
276 276 return m.remove(o)==PRESENT;
277 277 }
278 278
279 279 /**
280 280 * Removes all of the elements from this set.
281 281 * The set will be empty after this call returns.
282 282 */
283 283 public void clear() {
284 284 m.clear();
285 285 }
286 286
287 287 /**
288 288 * Adds all of the elements in the specified collection to this set.
289 289 *
290 290 * @param c collection containing elements to be added to this set
291 291 * @return {@code true} if this set changed as a result of the call
292 292 * @throws ClassCastException if the elements provided cannot be compared
293 293 * with the elements currently in the set
294 294 * @throws NullPointerException if the specified collection is null or
295 295 * if any element is null and this set uses natural ordering, or
296 296 * its comparator does not permit null elements
297 297 */
298 298 public boolean addAll(Collection<? extends E> c) {
299 299 // Use linear-time version if applicable
300 300 if (m.size()==0 && c.size() > 0 &&
301 301 c instanceof SortedSet &&
302 302 m instanceof TreeMap) {
303 303 SortedSet<? extends E> set = (SortedSet<? extends E>) c;
304 304 TreeMap<E,Object> map = (TreeMap<E, Object>) m;
305 305 Comparator<? super E> cc = (Comparator<? super E>) set.comparator();
306 306 Comparator<? super E> mc = map.comparator();
307 307 if (cc==mc || (cc != null && cc.equals(mc))) {
308 308 map.addAllForTreeSet(set, PRESENT);
309 309 return true;
310 310 }
311 311 }
312 312 return super.addAll(c);
313 313 }
314 314
315 315 /**
316 316 * @throws ClassCastException {@inheritDoc}
317 317 * @throws NullPointerException if {@code fromElement} or {@code toElement}
318 318 * is null and this set uses natural ordering, or its comparator
319 319 * does not permit null elements
320 320 * @throws IllegalArgumentException {@inheritDoc}
321 321 * @since 1.6
322 322 */
323 323 public NavigableSet<E> subSet(E fromElement, boolean fromInclusive,
324 324 E toElement, boolean toInclusive) {
325 325 return new TreeSet<E>(m.subMap(fromElement, fromInclusive,
326 326 toElement, toInclusive));
327 327 }
328 328
329 329 /**
330 330 * @throws ClassCastException {@inheritDoc}
331 331 * @throws NullPointerException if {@code toElement} is null and
332 332 * this set uses natural ordering, or its comparator does
333 333 * not permit null elements
334 334 * @throws IllegalArgumentException {@inheritDoc}
335 335 * @since 1.6
336 336 */
337 337 public NavigableSet<E> headSet(E toElement, boolean inclusive) {
338 338 return new TreeSet<E>(m.headMap(toElement, inclusive));
339 339 }
340 340
341 341 /**
342 342 * @throws ClassCastException {@inheritDoc}
343 343 * @throws NullPointerException if {@code fromElement} is null and
344 344 * this set uses natural ordering, or its comparator does
345 345 * not permit null elements
346 346 * @throws IllegalArgumentException {@inheritDoc}
347 347 * @since 1.6
348 348 */
349 349 public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
350 350 return new TreeSet<E>(m.tailMap(fromElement, inclusive));
351 351 }
352 352
353 353 /**
354 354 * @throws ClassCastException {@inheritDoc}
355 355 * @throws NullPointerException if {@code fromElement} or
356 356 * {@code toElement} is null and this set uses natural ordering,
357 357 * or its comparator does not permit null elements
358 358 * @throws IllegalArgumentException {@inheritDoc}
359 359 */
360 360 public SortedSet<E> subSet(E fromElement, E toElement) {
361 361 return subSet(fromElement, true, toElement, false);
362 362 }
363 363
364 364 /**
365 365 * @throws ClassCastException {@inheritDoc}
366 366 * @throws NullPointerException if {@code toElement} is null
367 367 * and this set uses natural ordering, or its comparator does
368 368 * not permit null elements
369 369 * @throws IllegalArgumentException {@inheritDoc}
370 370 */
371 371 public SortedSet<E> headSet(E toElement) {
372 372 return headSet(toElement, false);
373 373 }
374 374
375 375 /**
376 376 * @throws ClassCastException {@inheritDoc}
377 377 * @throws NullPointerException if {@code fromElement} is null
378 378 * and this set uses natural ordering, or its comparator does
379 379 * not permit null elements
380 380 * @throws IllegalArgumentException {@inheritDoc}
381 381 */
382 382 public SortedSet<E> tailSet(E fromElement) {
383 383 return tailSet(fromElement, true);
384 384 }
385 385
386 386 public Comparator<? super E> comparator() {
387 387 return m.comparator();
388 388 }
389 389
390 390 /**
391 391 * @throws NoSuchElementException {@inheritDoc}
392 392 */
393 393 public E first() {
394 394 return m.firstKey();
395 395 }
396 396
397 397 /**
398 398 * @throws NoSuchElementException {@inheritDoc}
399 399 */
400 400 public E last() {
401 401 return m.lastKey();
402 402 }
403 403
404 404 // NavigableSet API methods
405 405
406 406 /**
407 407 * @throws ClassCastException {@inheritDoc}
408 408 * @throws NullPointerException if the specified element is null
409 409 * and this set uses natural ordering, or its comparator
410 410 * does not permit null elements
411 411 * @since 1.6
412 412 */
413 413 public E lower(E e) {
414 414 return m.lowerKey(e);
415 415 }
416 416
417 417 /**
418 418 * @throws ClassCastException {@inheritDoc}
419 419 * @throws NullPointerException if the specified element is null
420 420 * and this set uses natural ordering, or its comparator
421 421 * does not permit null elements
422 422 * @since 1.6
423 423 */
424 424 public E floor(E e) {
425 425 return m.floorKey(e);
426 426 }
427 427
428 428 /**
429 429 * @throws ClassCastException {@inheritDoc}
430 430 * @throws NullPointerException if the specified element is null
431 431 * and this set uses natural ordering, or its comparator
432 432 * does not permit null elements
433 433 * @since 1.6
434 434 */
435 435 public E ceiling(E e) {
436 436 return m.ceilingKey(e);
437 437 }
438 438
439 439 /**
440 440 * @throws ClassCastException {@inheritDoc}
441 441 * @throws NullPointerException if the specified element is null
442 442 * and this set uses natural ordering, or its comparator
443 443 * does not permit null elements
444 444 * @since 1.6
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445 445 */
446 446 public E higher(E e) {
447 447 return m.higherKey(e);
448 448 }
449 449
450 450 /**
451 451 * @since 1.6
452 452 */
453 453 public E pollFirst() {
454 454 Map.Entry<E,?> e = m.pollFirstEntry();
455 - return (e == null)? null : e.getKey();
455 + return (e == null) ? null : e.getKey();
456 456 }
457 457
458 458 /**
459 459 * @since 1.6
460 460 */
461 461 public E pollLast() {
462 462 Map.Entry<E,?> e = m.pollLastEntry();
463 - return (e == null)? null : e.getKey();
463 + return (e == null) ? null : e.getKey();
464 464 }
465 465
466 466 /**
467 467 * Returns a shallow copy of this {@code TreeSet} instance. (The elements
468 468 * themselves are not cloned.)
469 469 *
470 470 * @return a shallow copy of this set
471 471 */
472 472 public Object clone() {
473 473 TreeSet<E> clone = null;
474 474 try {
475 475 clone = (TreeSet<E>) super.clone();
476 476 } catch (CloneNotSupportedException e) {
477 477 throw new InternalError();
478 478 }
479 479
480 480 clone.m = new TreeMap<E,Object>(m);
481 481 return clone;
482 482 }
483 483
484 484 /**
485 485 * Save the state of the {@code TreeSet} instance to a stream (that is,
486 486 * serialize it).
487 487 *
488 488 * @serialData Emits the comparator used to order this set, or
489 489 * {@code null} if it obeys its elements' natural ordering
490 490 * (Object), followed by the size of the set (the number of
491 491 * elements it contains) (int), followed by all of its
492 492 * elements (each an Object) in order (as determined by the
493 493 * set's Comparator, or by the elements' natural ordering if
494 494 * the set has no Comparator).
495 495 */
496 496 private void writeObject(java.io.ObjectOutputStream s)
497 497 throws java.io.IOException {
498 498 // Write out any hidden stuff
499 499 s.defaultWriteObject();
500 500
501 501 // Write out Comparator
502 502 s.writeObject(m.comparator());
503 503
504 504 // Write out size
505 505 s.writeInt(m.size());
506 506
507 507 // Write out all elements in the proper order.
508 508 for (E e : m.keySet())
509 509 s.writeObject(e);
510 510 }
511 511
512 512 /**
513 513 * Reconstitute the {@code TreeSet} instance from a stream (that is,
514 514 * deserialize it).
515 515 */
516 516 private void readObject(java.io.ObjectInputStream s)
517 517 throws java.io.IOException, ClassNotFoundException {
518 518 // Read in any hidden stuff
519 519 s.defaultReadObject();
520 520
521 521 // Read in Comparator
522 522 Comparator<? super E> c = (Comparator<? super E>) s.readObject();
523 523
524 524 // Create backing TreeMap
525 525 TreeMap<E,Object> tm;
526 526 if (c==null)
527 527 tm = new TreeMap<E,Object>();
528 528 else
529 529 tm = new TreeMap<E,Object>(c);
530 530 m = tm;
531 531
532 532 // Read in size
533 533 int size = s.readInt();
534 534
535 535 tm.readTreeSet(size, s, PRESENT);
536 536 }
537 537
538 538 private static final long serialVersionUID = -2479143000061671589L;
539 539 }
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