1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /*
26 * Written by Doug Lea with assistance from members of JCP JSR-166
27 * Expert Group. Adapted and released, under explicit permission,
28 * from JDK ArrayList.java which carries the following copyright:
29 *
30 * Copyright 1997 by Sun Microsystems, Inc.,
31 * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
32 * All rights reserved.
33 */
34
35 package java.util.concurrent;
36 import java.util.AbstractList;
37 import java.util.Arrays;
38 import java.util.Collection;
39 import java.util.Comparator;
40 import java.util.ConcurrentModificationException;
41 import java.util.Iterator;
42 import java.util.List;
43 import java.util.ListIterator;
44 import java.util.NoSuchElementException;
45 import java.util.Objects;
46 import java.util.RandomAccess;
47 import java.util.Spliterator;
48 import java.util.Spliterators;
49 import java.util.concurrent.locks.ReentrantLock;
50 import java.util.function.Consumer;
51 import java.util.function.Predicate;
52 import java.util.function.UnaryOperator;
53 import sun.misc.SharedSecrets;
54
55 /**
56 * A thread-safe variant of {@link java.util.ArrayList} in which all mutative
57 * operations ({@code add}, {@code set}, and so on) are implemented by
58 * making a fresh copy of the underlying array.
59 *
60 * <p>This is ordinarily too costly, but may be <em>more</em> efficient
61 * than alternatives when traversal operations vastly outnumber
62 * mutations, and is useful when you cannot or don't want to
63 * synchronize traversals, yet need to preclude interference among
64 * concurrent threads. The "snapshot" style iterator method uses a
65 * reference to the state of the array at the point that the iterator
66 * was created. This array never changes during the lifetime of the
67 * iterator, so interference is impossible and the iterator is
68 * guaranteed not to throw {@code ConcurrentModificationException}.
69 * The iterator will not reflect additions, removals, or changes to
70 * the list since the iterator was created. Element-changing
71 * operations on iterators themselves ({@code remove}, {@code set}, and
72 * {@code add}) are not supported. These methods throw
73 * {@code UnsupportedOperationException}.
74 *
75 * <p>All elements are permitted, including {@code null}.
76 *
77 * <p>Memory consistency effects: As with other concurrent
78 * collections, actions in a thread prior to placing an object into a
79 * {@code CopyOnWriteArrayList}
80 * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
81 * actions subsequent to the access or removal of that element from
82 * the {@code CopyOnWriteArrayList} in another thread.
83 *
84 * <p>This class is a member of the
85 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
86 * Java Collections Framework</a>.
87 *
88 * @since 1.5
89 * @author Doug Lea
90 * @param <E> the type of elements held in this collection
91 */
92 public class CopyOnWriteArrayList<E>
93 implements List<E>, RandomAccess, Cloneable, java.io.Serializable {
94 private static final long serialVersionUID = 8673264195747942595L;
95
96 /** The lock protecting all mutators */
97 final transient ReentrantLock lock = new ReentrantLock();
98
99 /** The array, accessed only via getArray/setArray. */
100 private transient volatile Object[] array;
101
102 /**
103 * Gets the array. Non-private so as to also be accessible
104 * from CopyOnWriteArraySet class.
105 */
106 final Object[] getArray() {
107 return array;
108 }
109
110 /**
111 * Sets the array.
112 */
113 final void setArray(Object[] a) {
114 array = a;
115 }
116
117 /**
118 * Creates an empty list.
119 */
120 public CopyOnWriteArrayList() {
121 setArray(new Object[0]);
122 }
123
124 /**
125 * Creates a list containing the elements of the specified
126 * collection, in the order they are returned by the collection's
127 * iterator.
128 *
129 * @param c the collection of initially held elements
130 * @throws NullPointerException if the specified collection is null
131 */
132 public CopyOnWriteArrayList(Collection<? extends E> c) {
133 Object[] elements;
134 if (c.getClass() == CopyOnWriteArrayList.class)
135 elements = ((CopyOnWriteArrayList<?>)c).getArray();
136 else {
137 elements = c.toArray();
138 // c.toArray might (incorrectly) not return Object[] (see 6260652)
139 if (elements.getClass() != Object[].class)
140 elements = Arrays.copyOf(elements, elements.length, Object[].class);
141 }
142 setArray(elements);
143 }
144
145 /**
146 * Creates a list holding a copy of the given array.
147 *
148 * @param toCopyIn the array (a copy of this array is used as the
149 * internal array)
150 * @throws NullPointerException if the specified array is null
151 */
152 public CopyOnWriteArrayList(E[] toCopyIn) {
153 setArray(Arrays.copyOf(toCopyIn, toCopyIn.length, Object[].class));
154 }
155
156 /**
157 * Returns the number of elements in this list.
158 *
159 * @return the number of elements in this list
160 */
161 public int size() {
162 return getArray().length;
163 }
164
165 /**
166 * Returns {@code true} if this list contains no elements.
167 *
168 * @return {@code true} if this list contains no elements
169 */
170 public boolean isEmpty() {
171 return size() == 0;
172 }
173
174 /**
175 * Tests for equality, coping with nulls.
176 */
177 private static boolean eq(Object o1, Object o2) {
178 return (o1 == null) ? o2 == null : o1.equals(o2);
179 }
180
181 /**
182 * static version of indexOf, to allow repeated calls without
183 * needing to re-acquire array each time.
184 * @param o element to search for
185 * @param elements the array
186 * @param index first index to search
187 * @param fence one past last index to search
188 * @return index of element, or -1 if absent
189 */
190 private static int indexOf(Object o, Object[] elements,
191 int index, int fence) {
192 if (o == null) {
193 for (int i = index; i < fence; i++)
194 if (elements[i] == null)
195 return i;
196 } else {
197 for (int i = index; i < fence; i++)
198 if (o.equals(elements[i]))
199 return i;
200 }
201 return -1;
202 }
203
204 /**
205 * static version of lastIndexOf.
206 * @param o element to search for
207 * @param elements the array
208 * @param index first index to search
209 * @return index of element, or -1 if absent
210 */
211 private static int lastIndexOf(Object o, Object[] elements, int index) {
212 if (o == null) {
213 for (int i = index; i >= 0; i--)
214 if (elements[i] == null)
215 return i;
216 } else {
217 for (int i = index; i >= 0; i--)
218 if (o.equals(elements[i]))
219 return i;
220 }
221 return -1;
222 }
223
224 /**
225 * Returns {@code true} if this list contains the specified element.
226 * More formally, returns {@code true} if and only if this list contains
227 * at least one element {@code e} such that
228 * <tt>(o==null ? e==null : o.equals(e))</tt>.
229 *
230 * @param o element whose presence in this list is to be tested
231 * @return {@code true} if this list contains the specified element
232 */
233 public boolean contains(Object o) {
234 Object[] elements = getArray();
235 return indexOf(o, elements, 0, elements.length) >= 0;
236 }
237
238 /**
239 * {@inheritDoc}
240 */
241 public int indexOf(Object o) {
242 Object[] elements = getArray();
243 return indexOf(o, elements, 0, elements.length);
244 }
245
246 /**
247 * Returns the index of the first occurrence of the specified element in
248 * this list, searching forwards from {@code index}, or returns -1 if
249 * the element is not found.
250 * More formally, returns the lowest index {@code i} such that
251 * <tt>(i >= index && (e==null ? get(i)==null : e.equals(get(i))))</tt>,
252 * or -1 if there is no such index.
253 *
254 * @param e element to search for
255 * @param index index to start searching from
256 * @return the index of the first occurrence of the element in
257 * this list at position {@code index} or later in the list;
258 * {@code -1} if the element is not found.
259 * @throws IndexOutOfBoundsException if the specified index is negative
260 */
261 public int indexOf(E e, int index) {
262 Object[] elements = getArray();
263 return indexOf(e, elements, index, elements.length);
264 }
265
266 /**
267 * {@inheritDoc}
268 */
269 public int lastIndexOf(Object o) {
270 Object[] elements = getArray();
271 return lastIndexOf(o, elements, elements.length - 1);
272 }
273
274 /**
275 * Returns the index of the last occurrence of the specified element in
276 * this list, searching backwards from {@code index}, or returns -1 if
277 * the element is not found.
278 * More formally, returns the highest index {@code i} such that
279 * <tt>(i <= index && (e==null ? get(i)==null : e.equals(get(i))))</tt>,
280 * or -1 if there is no such index.
281 *
282 * @param e element to search for
283 * @param index index to start searching backwards from
284 * @return the index of the last occurrence of the element at position
285 * less than or equal to {@code index} in this list;
286 * -1 if the element is not found.
287 * @throws IndexOutOfBoundsException if the specified index is greater
288 * than or equal to the current size of this list
289 */
290 public int lastIndexOf(E e, int index) {
291 Object[] elements = getArray();
292 return lastIndexOf(e, elements, index);
293 }
294
295 /**
296 * Returns a shallow copy of this list. (The elements themselves
297 * are not copied.)
298 *
299 * @return a clone of this list
300 */
301 public Object clone() {
302 try {
303 @SuppressWarnings("unchecked")
304 CopyOnWriteArrayList<E> clone =
305 (CopyOnWriteArrayList<E>) super.clone();
306 clone.resetLock();
307 return clone;
308 } catch (CloneNotSupportedException e) {
309 // this shouldn't happen, since we are Cloneable
310 throw new InternalError();
311 }
312 }
313
314 /**
315 * Returns an array containing all of the elements in this list
316 * in proper sequence (from first to last element).
317 *
318 * <p>The returned array will be "safe" in that no references to it are
319 * maintained by this list. (In other words, this method must allocate
320 * a new array). The caller is thus free to modify the returned array.
321 *
322 * <p>This method acts as bridge between array-based and collection-based
323 * APIs.
324 *
325 * @return an array containing all the elements in this list
326 */
327 public Object[] toArray() {
328 Object[] elements = getArray();
329 return Arrays.copyOf(elements, elements.length);
330 }
331
332 /**
333 * Returns an array containing all of the elements in this list in
334 * proper sequence (from first to last element); the runtime type of
335 * the returned array is that of the specified array. If the list fits
336 * in the specified array, it is returned therein. Otherwise, a new
337 * array is allocated with the runtime type of the specified array and
338 * the size of this list.
339 *
340 * <p>If this list fits in the specified array with room to spare
341 * (i.e., the array has more elements than this list), the element in
342 * the array immediately following the end of the list is set to
343 * {@code null}. (This is useful in determining the length of this
344 * list <i>only</i> if the caller knows that this list does not contain
345 * any null elements.)
346 *
347 * <p>Like the {@link #toArray()} method, this method acts as bridge between
348 * array-based and collection-based APIs. Further, this method allows
349 * precise control over the runtime type of the output array, and may,
350 * under certain circumstances, be used to save allocation costs.
351 *
352 * <p>Suppose {@code x} is a list known to contain only strings.
353 * The following code can be used to dump the list into a newly
354 * allocated array of {@code String}:
355 *
356 * <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
357 *
358 * Note that {@code toArray(new Object[0])} is identical in function to
359 * {@code toArray()}.
360 *
361 * @param a the array into which the elements of the list are to
362 * be stored, if it is big enough; otherwise, a new array of the
363 * same runtime type is allocated for this purpose.
364 * @return an array containing all the elements in this list
365 * @throws ArrayStoreException if the runtime type of the specified array
366 * is not a supertype of the runtime type of every element in
367 * this list
368 * @throws NullPointerException if the specified array is null
369 */
370 @SuppressWarnings("unchecked")
371 public <T> T[] toArray(T a[]) {
372 Object[] elements = getArray();
373 int len = elements.length;
374 if (a.length < len)
375 return (T[]) Arrays.copyOf(elements, len, a.getClass());
376 else {
377 System.arraycopy(elements, 0, a, 0, len);
378 if (a.length > len)
379 a[len] = null;
380 return a;
381 }
382 }
383
384 // Positional Access Operations
385
386 @SuppressWarnings("unchecked")
387 private E get(Object[] a, int index) {
388 return (E) a[index];
389 }
390
391 /**
392 * {@inheritDoc}
393 *
394 * @throws IndexOutOfBoundsException {@inheritDoc}
395 */
396 public E get(int index) {
397 return get(getArray(), index);
398 }
399
400 /**
401 * Replaces the element at the specified position in this list with the
402 * specified element.
403 *
404 * @throws IndexOutOfBoundsException {@inheritDoc}
405 */
406 public E set(int index, E element) {
407 final ReentrantLock lock = this.lock;
408 lock.lock();
409 try {
410 Object[] elements = getArray();
411 E oldValue = get(elements, index);
412
413 if (oldValue != element) {
414 int len = elements.length;
415 Object[] newElements = Arrays.copyOf(elements, len);
416 newElements[index] = element;
417 setArray(newElements);
418 } else {
419 // Not quite a no-op; ensures volatile write semantics
420 setArray(elements);
421 }
422 return oldValue;
423 } finally {
424 lock.unlock();
425 }
426 }
427
428 /**
429 * Appends the specified element to the end of this list.
430 *
431 * @param e element to be appended to this list
432 * @return {@code true} (as specified by {@link Collection#add})
433 */
434 public boolean add(E e) {
435 final ReentrantLock lock = this.lock;
436 lock.lock();
437 try {
438 Object[] elements = getArray();
439 int len = elements.length;
440 Object[] newElements = Arrays.copyOf(elements, len + 1);
441 newElements[len] = e;
442 setArray(newElements);
443 return true;
444 } finally {
445 lock.unlock();
446 }
447 }
448
449 /**
450 * Inserts the specified element at the specified position in this
451 * list. Shifts the element currently at that position (if any) and
452 * any subsequent elements to the right (adds one to their indices).
453 *
454 * @throws IndexOutOfBoundsException {@inheritDoc}
455 */
456 public void add(int index, E element) {
457 final ReentrantLock lock = this.lock;
458 lock.lock();
459 try {
460 Object[] elements = getArray();
461 int len = elements.length;
462 if (index > len || index < 0)
463 throw new IndexOutOfBoundsException("Index: "+index+
464 ", Size: "+len);
465 Object[] newElements;
466 int numMoved = len - index;
467 if (numMoved == 0)
468 newElements = Arrays.copyOf(elements, len + 1);
469 else {
470 newElements = new Object[len + 1];
471 System.arraycopy(elements, 0, newElements, 0, index);
472 System.arraycopy(elements, index, newElements, index + 1,
473 numMoved);
474 }
475 newElements[index] = element;
476 setArray(newElements);
477 } finally {
478 lock.unlock();
479 }
480 }
481
482 /**
483 * Removes the element at the specified position in this list.
484 * Shifts any subsequent elements to the left (subtracts one from their
485 * indices). Returns the element that was removed from the list.
486 *
487 * @throws IndexOutOfBoundsException {@inheritDoc}
488 */
489 public E remove(int index) {
490 final ReentrantLock lock = this.lock;
491 lock.lock();
492 try {
493 Object[] elements = getArray();
494 int len = elements.length;
495 E oldValue = get(elements, index);
496 int numMoved = len - index - 1;
497 if (numMoved == 0)
498 setArray(Arrays.copyOf(elements, len - 1));
499 else {
500 Object[] newElements = new Object[len - 1];
501 System.arraycopy(elements, 0, newElements, 0, index);
502 System.arraycopy(elements, index + 1, newElements, index,
503 numMoved);
504 setArray(newElements);
505 }
506 return oldValue;
507 } finally {
508 lock.unlock();
509 }
510 }
511
512 /**
513 * Removes the first occurrence of the specified element from this list,
514 * if it is present. If this list does not contain the element, it is
515 * unchanged. More formally, removes the element with the lowest index
516 * {@code i} such that
517 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>
518 * (if such an element exists). Returns {@code true} if this list
519 * contained the specified element (or equivalently, if this list
520 * changed as a result of the call).
521 *
522 * @param o element to be removed from this list, if present
523 * @return {@code true} if this list contained the specified element
524 */
525 public boolean remove(Object o) {
526 Object[] snapshot = getArray();
527 int index = indexOf(o, snapshot, 0, snapshot.length);
528 return (index < 0) ? false : remove(o, snapshot, index);
529 }
530
531 /**
532 * A version of remove(Object) using the strong hint that given
533 * recent snapshot contains o at the given index.
534 */
535 private boolean remove(Object o, Object[] snapshot, int index) {
536 final ReentrantLock lock = this.lock;
537 lock.lock();
538 try {
539 Object[] current = getArray();
540 int len = current.length;
541 if (snapshot != current) findIndex: {
542 int prefix = Math.min(index, len);
543 for (int i = 0; i < prefix; i++) {
544 if (current[i] != snapshot[i] && eq(o, current[i])) {
545 index = i;
546 break findIndex;
547 }
548 }
549 if (index >= len)
550 return false;
551 if (current[index] == o)
552 break findIndex;
553 index = indexOf(o, current, index, len);
554 if (index < 0)
555 return false;
556 }
557 Object[] newElements = new Object[len - 1];
558 System.arraycopy(current, 0, newElements, 0, index);
559 System.arraycopy(current, index + 1,
560 newElements, index,
561 len - index - 1);
562 setArray(newElements);
563 return true;
564 } finally {
565 lock.unlock();
566 }
567 }
568
569 /**
570 * Removes from this list all of the elements whose index is between
571 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
572 * Shifts any succeeding elements to the left (reduces their index).
573 * This call shortens the list by {@code (toIndex - fromIndex)} elements.
574 * (If {@code toIndex==fromIndex}, this operation has no effect.)
575 *
576 * @param fromIndex index of first element to be removed
577 * @param toIndex index after last element to be removed
578 * @throws IndexOutOfBoundsException if fromIndex or toIndex out of range
579 * ({@code fromIndex < 0 || toIndex > size() || toIndex < fromIndex})
580 */
581 void removeRange(int fromIndex, int toIndex) {
582 final ReentrantLock lock = this.lock;
583 lock.lock();
584 try {
585 Object[] elements = getArray();
586 int len = elements.length;
587
588 if (fromIndex < 0 || toIndex > len || toIndex < fromIndex)
589 throw new IndexOutOfBoundsException();
590 int newlen = len - (toIndex - fromIndex);
591 int numMoved = len - toIndex;
592 if (numMoved == 0)
593 setArray(Arrays.copyOf(elements, newlen));
594 else {
595 Object[] newElements = new Object[newlen];
596 System.arraycopy(elements, 0, newElements, 0, fromIndex);
597 System.arraycopy(elements, toIndex, newElements,
598 fromIndex, numMoved);
599 setArray(newElements);
600 }
601 } finally {
602 lock.unlock();
603 }
604 }
605
606 /**
607 * Appends the element, if not present.
608 *
609 * @param e element to be added to this list, if absent
610 * @return {@code true} if the element was added
611 */
612 public boolean addIfAbsent(E e) {
613 Object[] snapshot = getArray();
614 return indexOf(e, snapshot, 0, snapshot.length) >= 0 ? false :
615 addIfAbsent(e, snapshot);
616 }
617
618 /**
619 * A version of addIfAbsent using the strong hint that given
620 * recent snapshot does not contain e.
621 */
622 private boolean addIfAbsent(E e, Object[] snapshot) {
623 final ReentrantLock lock = this.lock;
624 lock.lock();
625 try {
626 Object[] current = getArray();
627 int len = current.length;
628 if (snapshot != current) {
629 // Optimize for lost race to another addXXX operation
630 int common = Math.min(snapshot.length, len);
631 for (int i = 0; i < common; i++)
632 if (current[i] != snapshot[i] && eq(e, current[i]))
633 return false;
634 if (indexOf(e, current, common, len) >= 0)
635 return false;
636 }
637 Object[] newElements = Arrays.copyOf(current, len + 1);
638 newElements[len] = e;
639 setArray(newElements);
640 return true;
641 } finally {
642 lock.unlock();
643 }
644 }
645
646 /**
647 * Returns {@code true} if this list contains all of the elements of the
648 * specified collection.
649 *
650 * @param c collection to be checked for containment in this list
651 * @return {@code true} if this list contains all of the elements of the
652 * specified collection
653 * @throws NullPointerException if the specified collection is null
654 * @see #contains(Object)
655 */
656 public boolean containsAll(Collection<?> c) {
657 Object[] elements = getArray();
658 int len = elements.length;
659 for (Object e : c) {
660 if (indexOf(e, elements, 0, len) < 0)
661 return false;
662 }
663 return true;
664 }
665
666 /**
667 * Removes from this list all of its elements that are contained in
668 * the specified collection. This is a particularly expensive operation
669 * in this class because of the need for an internal temporary array.
670 *
671 * @param c collection containing elements to be removed from this list
672 * @return {@code true} if this list changed as a result of the call
673 * @throws ClassCastException if the class of an element of this list
674 * is incompatible with the specified collection
675 * (<a href="../Collection.html#optional-restrictions">optional</a>)
676 * @throws NullPointerException if this list contains a null element and the
677 * specified collection does not permit null elements
678 * (<a href="../Collection.html#optional-restrictions">optional</a>),
679 * or if the specified collection is null
680 * @see #remove(Object)
681 */
682 public boolean removeAll(Collection<?> c) {
683 if (c == null) throw new NullPointerException();
684 final ReentrantLock lock = this.lock;
685 lock.lock();
686 try {
687 Object[] elements = getArray();
688 int len = elements.length;
689 if (len != 0) {
690 // temp array holds those elements we know we want to keep
691 int newlen = 0;
692 Object[] temp = new Object[len];
693 for (int i = 0; i < len; ++i) {
694 Object element = elements[i];
695 if (!c.contains(element))
696 temp[newlen++] = element;
697 }
698 if (newlen != len) {
699 setArray(Arrays.copyOf(temp, newlen));
700 return true;
701 }
702 }
703 return false;
704 } finally {
705 lock.unlock();
706 }
707 }
708
709 /**
710 * Retains only the elements in this list that are contained in the
711 * specified collection. In other words, removes from this list all of
712 * its elements that are not contained in the specified collection.
713 *
714 * @param c collection containing elements to be retained in this list
715 * @return {@code true} if this list changed as a result of the call
716 * @throws ClassCastException if the class of an element of this list
717 * is incompatible with the specified collection
718 * (<a href="../Collection.html#optional-restrictions">optional</a>)
719 * @throws NullPointerException if this list contains a null element and the
720 * specified collection does not permit null elements
721 * (<a href="../Collection.html#optional-restrictions">optional</a>),
722 * or if the specified collection is null
723 * @see #remove(Object)
724 */
725 public boolean retainAll(Collection<?> c) {
726 if (c == null) throw new NullPointerException();
727 final ReentrantLock lock = this.lock;
728 lock.lock();
729 try {
730 Object[] elements = getArray();
731 int len = elements.length;
732 if (len != 0) {
733 // temp array holds those elements we know we want to keep
734 int newlen = 0;
735 Object[] temp = new Object[len];
736 for (int i = 0; i < len; ++i) {
737 Object element = elements[i];
738 if (c.contains(element))
739 temp[newlen++] = element;
740 }
741 if (newlen != len) {
742 setArray(Arrays.copyOf(temp, newlen));
743 return true;
744 }
745 }
746 return false;
747 } finally {
748 lock.unlock();
749 }
750 }
751
752 /**
753 * Appends all of the elements in the specified collection that
754 * are not already contained in this list, to the end of
755 * this list, in the order that they are returned by the
756 * specified collection's iterator.
757 *
758 * @param c collection containing elements to be added to this list
759 * @return the number of elements added
760 * @throws NullPointerException if the specified collection is null
761 * @see #addIfAbsent(Object)
762 */
763 public int addAllAbsent(Collection<? extends E> c) {
764 Object[] cs = c.toArray();
765 if (cs.length == 0)
766 return 0;
767 final ReentrantLock lock = this.lock;
768 lock.lock();
769 try {
770 Object[] elements = getArray();
771 int len = elements.length;
772 int added = 0;
773 // uniquify and compact elements in cs
774 for (int i = 0; i < cs.length; ++i) {
775 Object e = cs[i];
776 if (indexOf(e, elements, 0, len) < 0 &&
777 indexOf(e, cs, 0, added) < 0)
778 cs[added++] = e;
779 }
780 if (added > 0) {
781 Object[] newElements = Arrays.copyOf(elements, len + added);
782 System.arraycopy(cs, 0, newElements, len, added);
783 setArray(newElements);
784 }
785 return added;
786 } finally {
787 lock.unlock();
788 }
789 }
790
791 /**
792 * Removes all of the elements from this list.
793 * The list will be empty after this call returns.
794 */
795 public void clear() {
796 final ReentrantLock lock = this.lock;
797 lock.lock();
798 try {
799 setArray(new Object[0]);
800 } finally {
801 lock.unlock();
802 }
803 }
804
805 /**
806 * Appends all of the elements in the specified collection to the end
807 * of this list, in the order that they are returned by the specified
808 * collection's iterator.
809 *
810 * @param c collection containing elements to be added to this list
811 * @return {@code true} if this list changed as a result of the call
812 * @throws NullPointerException if the specified collection is null
813 * @see #add(Object)
814 */
815 public boolean addAll(Collection<? extends E> c) {
816 Object[] cs = (c.getClass() == CopyOnWriteArrayList.class) ?
817 ((CopyOnWriteArrayList<?>)c).getArray() : c.toArray();
818 if (cs.length == 0)
819 return false;
820 final ReentrantLock lock = this.lock;
821 lock.lock();
822 try {
823 Object[] elements = getArray();
824 int len = elements.length;
825 if (len == 0 && cs.getClass() == Object[].class)
826 setArray(cs);
827 else {
828 Object[] newElements = Arrays.copyOf(elements, len + cs.length);
829 System.arraycopy(cs, 0, newElements, len, cs.length);
830 setArray(newElements);
831 }
832 return true;
833 } finally {
834 lock.unlock();
835 }
836 }
837
838 /**
839 * Inserts all of the elements in the specified collection into this
840 * list, starting at the specified position. Shifts the element
841 * currently at that position (if any) and any subsequent elements to
842 * the right (increases their indices). The new elements will appear
843 * in this list in the order that they are returned by the
844 * specified collection's iterator.
845 *
846 * @param index index at which to insert the first element
847 * from the specified collection
848 * @param c collection containing elements to be added to this list
849 * @return {@code true} if this list changed as a result of the call
850 * @throws IndexOutOfBoundsException {@inheritDoc}
851 * @throws NullPointerException if the specified collection is null
852 * @see #add(int,Object)
853 */
854 public boolean addAll(int index, Collection<? extends E> c) {
855 Object[] cs = c.toArray();
856 final ReentrantLock lock = this.lock;
857 lock.lock();
858 try {
859 Object[] elements = getArray();
860 int len = elements.length;
861 if (index > len || index < 0)
862 throw new IndexOutOfBoundsException("Index: "+index+
863 ", Size: "+len);
864 if (cs.length == 0)
865 return false;
866 int numMoved = len - index;
867 Object[] newElements;
868 if (numMoved == 0)
869 newElements = Arrays.copyOf(elements, len + cs.length);
870 else {
871 newElements = new Object[len + cs.length];
872 System.arraycopy(elements, 0, newElements, 0, index);
873 System.arraycopy(elements, index,
874 newElements, index + cs.length,
875 numMoved);
876 }
877 System.arraycopy(cs, 0, newElements, index, cs.length);
878 setArray(newElements);
879 return true;
880 } finally {
881 lock.unlock();
882 }
883 }
884
885 public void forEach(Consumer<? super E> action) {
886 if (action == null) throw new NullPointerException();
887 Object[] elements = getArray();
888 int len = elements.length;
889 for (int i = 0; i < len; ++i) {
890 @SuppressWarnings("unchecked") E e = (E) elements[i];
891 action.accept(e);
892 }
893 }
894
895 public boolean removeIf(Predicate<? super E> filter) {
896 if (filter == null) throw new NullPointerException();
897 final ReentrantLock lock = this.lock;
898 lock.lock();
899 try {
900 Object[] elements = getArray();
901 int len = elements.length;
902 if (len != 0) {
903 int newlen = 0;
904 Object[] temp = new Object[len];
905 for (int i = 0; i < len; ++i) {
906 @SuppressWarnings("unchecked") E e = (E) elements[i];
907 if (!filter.test(e))
908 temp[newlen++] = e;
909 }
910 if (newlen != len) {
911 setArray(Arrays.copyOf(temp, newlen));
912 return true;
913 }
914 }
915 return false;
916 } finally {
917 lock.unlock();
918 }
919 }
920
921 public void replaceAll(UnaryOperator<E> operator) {
922 if (operator == null) throw new NullPointerException();
923 final ReentrantLock lock = this.lock;
924 lock.lock();
925 try {
926 Object[] elements = getArray();
927 int len = elements.length;
928 Object[] newElements = Arrays.copyOf(elements, len);
929 for (int i = 0; i < len; ++i) {
930 @SuppressWarnings("unchecked") E e = (E) elements[i];
931 newElements[i] = operator.apply(e);
932 }
933 setArray(newElements);
934 } finally {
935 lock.unlock();
936 }
937 }
938
939 public void sort(Comparator<? super E> c) {
940 final ReentrantLock lock = this.lock;
941 lock.lock();
942 try {
943 Object[] elements = getArray();
944 Object[] newElements = Arrays.copyOf(elements, elements.length);
945 @SuppressWarnings("unchecked") E[] es = (E[])newElements;
946 Arrays.sort(es, c);
947 setArray(newElements);
948 } finally {
949 lock.unlock();
950 }
951 }
952
953 /**
954 * Saves this list to a stream (that is, serializes it).
955 *
956 * @param s the stream
957 * @throws java.io.IOException if an I/O error occurs
958 * @serialData The length of the array backing the list is emitted
959 * (int), followed by all of its elements (each an Object)
960 * in the proper order.
961 */
962 private void writeObject(java.io.ObjectOutputStream s)
963 throws java.io.IOException {
964
965 s.defaultWriteObject();
966
967 Object[] elements = getArray();
968 // Write out array length
969 s.writeInt(elements.length);
970
971 // Write out all elements in the proper order.
972 for (Object element : elements)
973 s.writeObject(element);
974 }
975
976 /**
977 * Reconstitutes this list from a stream (that is, deserializes it).
978 * @param s the stream
979 * @throws ClassNotFoundException if the class of a serialized object
980 * could not be found
981 * @throws java.io.IOException if an I/O error occurs
982 */
983 private void readObject(java.io.ObjectInputStream s)
984 throws java.io.IOException, ClassNotFoundException {
985
986 s.defaultReadObject();
987
988 // bind to new lock
989 resetLock();
990
991 // Read in array length and allocate array
992 int len = s.readInt();
993 SharedSecrets.getJavaOISAccess().checkArray(s, Object[].class, len);
994 Object[] elements = new Object[len];
995
996 // Read in all elements in the proper order.
997 for (int i = 0; i < len; i++)
998 elements[i] = s.readObject();
999 setArray(elements);
1000 }
1001
1002 /**
1003 * Returns a string representation of this list. The string
1004 * representation consists of the string representations of the list's
1005 * elements in the order they are returned by its iterator, enclosed in
1006 * square brackets ({@code "[]"}). Adjacent elements are separated by
1007 * the characters {@code ", "} (comma and space). Elements are
1008 * converted to strings as by {@link String#valueOf(Object)}.
1009 *
1010 * @return a string representation of this list
1011 */
1012 public String toString() {
1013 return Arrays.toString(getArray());
1014 }
1015
1016 /**
1017 * Compares the specified object with this list for equality.
1018 * Returns {@code true} if the specified object is the same object
1019 * as this object, or if it is also a {@link List} and the sequence
1020 * of elements returned by an {@linkplain List#iterator() iterator}
1021 * over the specified list is the same as the sequence returned by
1022 * an iterator over this list. The two sequences are considered to
1023 * be the same if they have the same length and corresponding
1024 * elements at the same position in the sequence are <em>equal</em>.
1025 * Two elements {@code e1} and {@code e2} are considered
1026 * <em>equal</em> if {@code (e1==null ? e2==null : e1.equals(e2))}.
1027 *
1028 * @param o the object to be compared for equality with this list
1029 * @return {@code true} if the specified object is equal to this list
1030 */
1031 public boolean equals(Object o) {
1032 if (o == this)
1033 return true;
1034 if (!(o instanceof List))
1035 return false;
1036
1037 List<?> list = (List<?>)(o);
1038 Iterator<?> it = list.iterator();
1039 Object[] elements = getArray();
1040 int len = elements.length;
1041 for (int i = 0; i < len; ++i)
1042 if (!it.hasNext() || !eq(elements[i], it.next()))
1043 return false;
1044 if (it.hasNext())
1045 return false;
1046 return true;
1047 }
1048
1049 /**
1050 * Returns the hash code value for this list.
1051 *
1052 * <p>This implementation uses the definition in {@link List#hashCode}.
1053 *
1054 * @return the hash code value for this list
1055 */
1056 public int hashCode() {
1057 int hashCode = 1;
1058 Object[] elements = getArray();
1059 int len = elements.length;
1060 for (int i = 0; i < len; ++i) {
1061 Object obj = elements[i];
1062 hashCode = 31*hashCode + (obj==null ? 0 : obj.hashCode());
1063 }
1064 return hashCode;
1065 }
1066
1067 /**
1068 * Returns an iterator over the elements in this list in proper sequence.
1069 *
1070 * <p>The returned iterator provides a snapshot of the state of the list
1071 * when the iterator was constructed. No synchronization is needed while
1072 * traversing the iterator. The iterator does <em>NOT</em> support the
1073 * {@code remove} method.
1074 *
1075 * @return an iterator over the elements in this list in proper sequence
1076 */
1077 public Iterator<E> iterator() {
1078 return new COWIterator<E>(getArray(), 0);
1079 }
1080
1081 /**
1082 * {@inheritDoc}
1083 *
1084 * <p>The returned iterator provides a snapshot of the state of the list
1085 * when the iterator was constructed. No synchronization is needed while
1086 * traversing the iterator. The iterator does <em>NOT</em> support the
1087 * {@code remove}, {@code set} or {@code add} methods.
1088 */
1089 public ListIterator<E> listIterator() {
1090 return new COWIterator<E>(getArray(), 0);
1091 }
1092
1093 /**
1094 * {@inheritDoc}
1095 *
1096 * <p>The returned iterator provides a snapshot of the state of the list
1097 * when the iterator was constructed. No synchronization is needed while
1098 * traversing the iterator. The iterator does <em>NOT</em> support the
1099 * {@code remove}, {@code set} or {@code add} methods.
1100 *
1101 * @throws IndexOutOfBoundsException {@inheritDoc}
1102 */
1103 public ListIterator<E> listIterator(int index) {
1104 Object[] elements = getArray();
1105 int len = elements.length;
1106 if (index < 0 || index > len)
1107 throw new IndexOutOfBoundsException("Index: "+index);
1108
1109 return new COWIterator<E>(elements, index);
1110 }
1111
1112 /**
1113 * Returns a {@link Spliterator} over the elements in this list.
1114 *
1115 * <p>The {@code Spliterator} reports {@link Spliterator#IMMUTABLE},
1116 * {@link Spliterator#ORDERED}, {@link Spliterator#SIZED}, and
1117 * {@link Spliterator#SUBSIZED}.
1118 *
1119 * <p>The spliterator provides a snapshot of the state of the list
1120 * when the spliterator was constructed. No synchronization is needed while
1121 * operating on the spliterator.
1122 *
1123 * @return a {@code Spliterator} over the elements in this list
1124 * @since 1.8
1125 */
1126 public Spliterator<E> spliterator() {
1127 return Spliterators.spliterator
1128 (getArray(), Spliterator.IMMUTABLE | Spliterator.ORDERED);
1129 }
1130
1131 static final class COWIterator<E> implements ListIterator<E> {
1132 /** Snapshot of the array */
1133 private final Object[] snapshot;
1134 /** Index of element to be returned by subsequent call to next. */
1135 private int cursor;
1136
1137 private COWIterator(Object[] elements, int initialCursor) {
1138 cursor = initialCursor;
1139 snapshot = elements;
1140 }
1141
1142 public boolean hasNext() {
1143 return cursor < snapshot.length;
1144 }
1145
1146 public boolean hasPrevious() {
1147 return cursor > 0;
1148 }
1149
1150 @SuppressWarnings("unchecked")
1151 public E next() {
1152 if (! hasNext())
1153 throw new NoSuchElementException();
1154 return (E) snapshot[cursor++];
1155 }
1156
1157 @SuppressWarnings("unchecked")
1158 public E previous() {
1159 if (! hasPrevious())
1160 throw new NoSuchElementException();
1161 return (E) snapshot[--cursor];
1162 }
1163
1164 public int nextIndex() {
1165 return cursor;
1166 }
1167
1168 public int previousIndex() {
1169 return cursor-1;
1170 }
1171
1172 /**
1173 * Not supported. Always throws UnsupportedOperationException.
1174 * @throws UnsupportedOperationException always; {@code remove}
1175 * is not supported by this iterator.
1176 */
1177 public void remove() {
1178 throw new UnsupportedOperationException();
1179 }
1180
1181 /**
1182 * Not supported. Always throws UnsupportedOperationException.
1183 * @throws UnsupportedOperationException always; {@code set}
1184 * is not supported by this iterator.
1185 */
1186 public void set(E e) {
1187 throw new UnsupportedOperationException();
1188 }
1189
1190 /**
1191 * Not supported. Always throws UnsupportedOperationException.
1192 * @throws UnsupportedOperationException always; {@code add}
1193 * is not supported by this iterator.
1194 */
1195 public void add(E e) {
1196 throw new UnsupportedOperationException();
1197 }
1198
1199 @Override
1200 public void forEachRemaining(Consumer<? super E> action) {
1201 Objects.requireNonNull(action);
1202 Object[] elements = snapshot;
1203 final int size = elements.length;
1204 for (int i = cursor; i < size; i++) {
1205 @SuppressWarnings("unchecked") E e = (E) elements[i];
1206 action.accept(e);
1207 }
1208 cursor = size;
1209 }
1210 }
1211
1212 /**
1213 * Returns a view of the portion of this list between
1214 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
1215 * The returned list is backed by this list, so changes in the
1216 * returned list are reflected in this list.
1217 *
1218 * <p>The semantics of the list returned by this method become
1219 * undefined if the backing list (i.e., this list) is modified in
1220 * any way other than via the returned list.
1221 *
1222 * @param fromIndex low endpoint (inclusive) of the subList
1223 * @param toIndex high endpoint (exclusive) of the subList
1224 * @return a view of the specified range within this list
1225 * @throws IndexOutOfBoundsException {@inheritDoc}
1226 */
1227 public List<E> subList(int fromIndex, int toIndex) {
1228 final ReentrantLock lock = this.lock;
1229 lock.lock();
1230 try {
1231 Object[] elements = getArray();
1232 int len = elements.length;
1233 if (fromIndex < 0 || toIndex > len || fromIndex > toIndex)
1234 throw new IndexOutOfBoundsException();
1235 return new COWSubList<E>(this, fromIndex, toIndex);
1236 } finally {
1237 lock.unlock();
1238 }
1239 }
1240
1241 /**
1242 * Sublist for CopyOnWriteArrayList.
1243 * This class extends AbstractList merely for convenience, to
1244 * avoid having to define addAll, etc. This doesn't hurt, but
1245 * is wasteful. This class does not need or use modCount
1246 * mechanics in AbstractList, but does need to check for
1247 * concurrent modification using similar mechanics. On each
1248 * operation, the array that we expect the backing list to use
1249 * is checked and updated. Since we do this for all of the
1250 * base operations invoked by those defined in AbstractList,
1251 * all is well. While inefficient, this is not worth
1252 * improving. The kinds of list operations inherited from
1253 * AbstractList are already so slow on COW sublists that
1254 * adding a bit more space/time doesn't seem even noticeable.
1255 */
1256 private static class COWSubList<E>
1257 extends AbstractList<E>
1258 implements RandomAccess
1259 {
1260 private final CopyOnWriteArrayList<E> l;
1261 private final int offset;
1262 private int size;
1263 private Object[] expectedArray;
1264
1265 // only call this holding l's lock
1266 COWSubList(CopyOnWriteArrayList<E> list,
1267 int fromIndex, int toIndex) {
1268 l = list;
1269 expectedArray = l.getArray();
1270 offset = fromIndex;
1271 size = toIndex - fromIndex;
1272 }
1273
1274 // only call this holding l's lock
1275 private void checkForComodification() {
1276 if (l.getArray() != expectedArray)
1277 throw new ConcurrentModificationException();
1278 }
1279
1280 // only call this holding l's lock
1281 private void rangeCheck(int index) {
1282 if (index < 0 || index >= size)
1283 throw new IndexOutOfBoundsException("Index: "+index+
1284 ",Size: "+size);
1285 }
1286
1287 public E set(int index, E element) {
1288 final ReentrantLock lock = l.lock;
1289 lock.lock();
1290 try {
1291 rangeCheck(index);
1292 checkForComodification();
1293 E x = l.set(index+offset, element);
1294 expectedArray = l.getArray();
1295 return x;
1296 } finally {
1297 lock.unlock();
1298 }
1299 }
1300
1301 public E get(int index) {
1302 final ReentrantLock lock = l.lock;
1303 lock.lock();
1304 try {
1305 rangeCheck(index);
1306 checkForComodification();
1307 return l.get(index+offset);
1308 } finally {
1309 lock.unlock();
1310 }
1311 }
1312
1313 public int size() {
1314 final ReentrantLock lock = l.lock;
1315 lock.lock();
1316 try {
1317 checkForComodification();
1318 return size;
1319 } finally {
1320 lock.unlock();
1321 }
1322 }
1323
1324 public void add(int index, E element) {
1325 final ReentrantLock lock = l.lock;
1326 lock.lock();
1327 try {
1328 checkForComodification();
1329 if (index < 0 || index > size)
1330 throw new IndexOutOfBoundsException();
1331 l.add(index+offset, element);
1332 expectedArray = l.getArray();
1333 size++;
1334 } finally {
1335 lock.unlock();
1336 }
1337 }
1338
1339 public void clear() {
1340 final ReentrantLock lock = l.lock;
1341 lock.lock();
1342 try {
1343 checkForComodification();
1344 l.removeRange(offset, offset+size);
1345 expectedArray = l.getArray();
1346 size = 0;
1347 } finally {
1348 lock.unlock();
1349 }
1350 }
1351
1352 public E remove(int index) {
1353 final ReentrantLock lock = l.lock;
1354 lock.lock();
1355 try {
1356 rangeCheck(index);
1357 checkForComodification();
1358 E result = l.remove(index+offset);
1359 expectedArray = l.getArray();
1360 size--;
1361 return result;
1362 } finally {
1363 lock.unlock();
1364 }
1365 }
1366
1367 public boolean remove(Object o) {
1368 int index = indexOf(o);
1369 if (index == -1)
1370 return false;
1371 remove(index);
1372 return true;
1373 }
1374
1375 public Iterator<E> iterator() {
1376 final ReentrantLock lock = l.lock;
1377 lock.lock();
1378 try {
1379 checkForComodification();
1380 return new COWSubListIterator<E>(l, 0, offset, size);
1381 } finally {
1382 lock.unlock();
1383 }
1384 }
1385
1386 public ListIterator<E> listIterator(int index) {
1387 final ReentrantLock lock = l.lock;
1388 lock.lock();
1389 try {
1390 checkForComodification();
1391 if (index < 0 || index > size)
1392 throw new IndexOutOfBoundsException("Index: "+index+
1393 ", Size: "+size);
1394 return new COWSubListIterator<E>(l, index, offset, size);
1395 } finally {
1396 lock.unlock();
1397 }
1398 }
1399
1400 public List<E> subList(int fromIndex, int toIndex) {
1401 final ReentrantLock lock = l.lock;
1402 lock.lock();
1403 try {
1404 checkForComodification();
1405 if (fromIndex < 0 || toIndex > size || fromIndex > toIndex)
1406 throw new IndexOutOfBoundsException();
1407 return new COWSubList<E>(l, fromIndex + offset,
1408 toIndex + offset);
1409 } finally {
1410 lock.unlock();
1411 }
1412 }
1413
1414 public void forEach(Consumer<? super E> action) {
1415 if (action == null) throw new NullPointerException();
1416 int lo = offset;
1417 int hi = offset + size;
1418 Object[] a = expectedArray;
1419 if (l.getArray() != a)
1420 throw new ConcurrentModificationException();
1421 if (lo < 0 || hi > a.length)
1422 throw new IndexOutOfBoundsException();
1423 for (int i = lo; i < hi; ++i) {
1424 @SuppressWarnings("unchecked") E e = (E) a[i];
1425 action.accept(e);
1426 }
1427 }
1428
1429 public void replaceAll(UnaryOperator<E> operator) {
1430 if (operator == null) throw new NullPointerException();
1431 final ReentrantLock lock = l.lock;
1432 lock.lock();
1433 try {
1434 int lo = offset;
1435 int hi = offset + size;
1436 Object[] elements = expectedArray;
1437 if (l.getArray() != elements)
1438 throw new ConcurrentModificationException();
1439 int len = elements.length;
1440 if (lo < 0 || hi > len)
1441 throw new IndexOutOfBoundsException();
1442 Object[] newElements = Arrays.copyOf(elements, len);
1443 for (int i = lo; i < hi; ++i) {
1444 @SuppressWarnings("unchecked") E e = (E) elements[i];
1445 newElements[i] = operator.apply(e);
1446 }
1447 l.setArray(expectedArray = newElements);
1448 } finally {
1449 lock.unlock();
1450 }
1451 }
1452
1453 public void sort(Comparator<? super E> c) {
1454 final ReentrantLock lock = l.lock;
1455 lock.lock();
1456 try {
1457 int lo = offset;
1458 int hi = offset + size;
1459 Object[] elements = expectedArray;
1460 if (l.getArray() != elements)
1461 throw new ConcurrentModificationException();
1462 int len = elements.length;
1463 if (lo < 0 || hi > len)
1464 throw new IndexOutOfBoundsException();
1465 Object[] newElements = Arrays.copyOf(elements, len);
1466 @SuppressWarnings("unchecked") E[] es = (E[])newElements;
1467 Arrays.sort(es, lo, hi, c);
1468 l.setArray(expectedArray = newElements);
1469 } finally {
1470 lock.unlock();
1471 }
1472 }
1473
1474 public boolean removeAll(Collection<?> c) {
1475 if (c == null) throw new NullPointerException();
1476 boolean removed = false;
1477 final ReentrantLock lock = l.lock;
1478 lock.lock();
1479 try {
1480 int n = size;
1481 if (n > 0) {
1482 int lo = offset;
1483 int hi = offset + n;
1484 Object[] elements = expectedArray;
1485 if (l.getArray() != elements)
1486 throw new ConcurrentModificationException();
1487 int len = elements.length;
1488 if (lo < 0 || hi > len)
1489 throw new IndexOutOfBoundsException();
1490 int newSize = 0;
1491 Object[] temp = new Object[n];
1492 for (int i = lo; i < hi; ++i) {
1493 Object element = elements[i];
1494 if (!c.contains(element))
1495 temp[newSize++] = element;
1496 }
1497 if (newSize != n) {
1498 Object[] newElements = new Object[len - n + newSize];
1499 System.arraycopy(elements, 0, newElements, 0, lo);
1500 System.arraycopy(temp, 0, newElements, lo, newSize);
1501 System.arraycopy(elements, hi, newElements,
1502 lo + newSize, len - hi);
1503 size = newSize;
1504 removed = true;
1505 l.setArray(expectedArray = newElements);
1506 }
1507 }
1508 } finally {
1509 lock.unlock();
1510 }
1511 return removed;
1512 }
1513
1514 public boolean retainAll(Collection<?> c) {
1515 if (c == null) throw new NullPointerException();
1516 boolean removed = false;
1517 final ReentrantLock lock = l.lock;
1518 lock.lock();
1519 try {
1520 int n = size;
1521 if (n > 0) {
1522 int lo = offset;
1523 int hi = offset + n;
1524 Object[] elements = expectedArray;
1525 if (l.getArray() != elements)
1526 throw new ConcurrentModificationException();
1527 int len = elements.length;
1528 if (lo < 0 || hi > len)
1529 throw new IndexOutOfBoundsException();
1530 int newSize = 0;
1531 Object[] temp = new Object[n];
1532 for (int i = lo; i < hi; ++i) {
1533 Object element = elements[i];
1534 if (c.contains(element))
1535 temp[newSize++] = element;
1536 }
1537 if (newSize != n) {
1538 Object[] newElements = new Object[len - n + newSize];
1539 System.arraycopy(elements, 0, newElements, 0, lo);
1540 System.arraycopy(temp, 0, newElements, lo, newSize);
1541 System.arraycopy(elements, hi, newElements,
1542 lo + newSize, len - hi);
1543 size = newSize;
1544 removed = true;
1545 l.setArray(expectedArray = newElements);
1546 }
1547 }
1548 } finally {
1549 lock.unlock();
1550 }
1551 return removed;
1552 }
1553
1554 public boolean removeIf(Predicate<? super E> filter) {
1555 if (filter == null) throw new NullPointerException();
1556 boolean removed = false;
1557 final ReentrantLock lock = l.lock;
1558 lock.lock();
1559 try {
1560 int n = size;
1561 if (n > 0) {
1562 int lo = offset;
1563 int hi = offset + n;
1564 Object[] elements = expectedArray;
1565 if (l.getArray() != elements)
1566 throw new ConcurrentModificationException();
1567 int len = elements.length;
1568 if (lo < 0 || hi > len)
1569 throw new IndexOutOfBoundsException();
1570 int newSize = 0;
1571 Object[] temp = new Object[n];
1572 for (int i = lo; i < hi; ++i) {
1573 @SuppressWarnings("unchecked") E e = (E) elements[i];
1574 if (!filter.test(e))
1575 temp[newSize++] = e;
1576 }
1577 if (newSize != n) {
1578 Object[] newElements = new Object[len - n + newSize];
1579 System.arraycopy(elements, 0, newElements, 0, lo);
1580 System.arraycopy(temp, 0, newElements, lo, newSize);
1581 System.arraycopy(elements, hi, newElements,
1582 lo + newSize, len - hi);
1583 size = newSize;
1584 removed = true;
1585 l.setArray(expectedArray = newElements);
1586 }
1587 }
1588 } finally {
1589 lock.unlock();
1590 }
1591 return removed;
1592 }
1593
1594 public Spliterator<E> spliterator() {
1595 int lo = offset;
1596 int hi = offset + size;
1597 Object[] a = expectedArray;
1598 if (l.getArray() != a)
1599 throw new ConcurrentModificationException();
1600 if (lo < 0 || hi > a.length)
1601 throw new IndexOutOfBoundsException();
1602 return Spliterators.spliterator
1603 (a, lo, hi, Spliterator.IMMUTABLE | Spliterator.ORDERED);
1604 }
1605
1606 }
1607
1608 private static class COWSubListIterator<E> implements ListIterator<E> {
1609 private final ListIterator<E> it;
1610 private final int offset;
1611 private final int size;
1612
1613 COWSubListIterator(List<E> l, int index, int offset, int size) {
1614 this.offset = offset;
1615 this.size = size;
1616 it = l.listIterator(index+offset);
1617 }
1618
1619 public boolean hasNext() {
1620 return nextIndex() < size;
1621 }
1622
1623 public E next() {
1624 if (hasNext())
1625 return it.next();
1626 else
1627 throw new NoSuchElementException();
1628 }
1629
1630 public boolean hasPrevious() {
1631 return previousIndex() >= 0;
1632 }
1633
1634 public E previous() {
1635 if (hasPrevious())
1636 return it.previous();
1637 else
1638 throw new NoSuchElementException();
1639 }
1640
1641 public int nextIndex() {
1642 return it.nextIndex() - offset;
1643 }
1644
1645 public int previousIndex() {
1646 return it.previousIndex() - offset;
1647 }
1648
1649 public void remove() {
1650 throw new UnsupportedOperationException();
1651 }
1652
1653 public void set(E e) {
1654 throw new UnsupportedOperationException();
1655 }
1656
1657 public void add(E e) {
1658 throw new UnsupportedOperationException();
1659 }
1660
1661 @Override
1662 public void forEachRemaining(Consumer<? super E> action) {
1663 Objects.requireNonNull(action);
1664 int s = size;
1665 ListIterator<E> i = it;
1666 while (nextIndex() < s) {
1667 action.accept(i.next());
1668 }
1669 }
1670 }
1671
1672 // Support for resetting lock while deserializing
1673 private void resetLock() {
1674 UNSAFE.putObjectVolatile(this, lockOffset, new ReentrantLock());
1675 }
1676 private static final sun.misc.Unsafe UNSAFE;
1677 private static final long lockOffset;
1678 static {
1679 try {
1680 UNSAFE = sun.misc.Unsafe.getUnsafe();
1681 Class<?> k = CopyOnWriteArrayList.class;
1682 lockOffset = UNSAFE.objectFieldOffset
1683 (k.getDeclaredField("lock"));
1684 } catch (Exception e) {
1685 throw new Error(e);
1686 }
1687 }
1688 }