1 /*
2 * Copyright (c) 1997, 2016, 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 import java.util.function.Consumer;
29 import java.util.function.Predicate;
30 import java.util.function.UnaryOperator;
31
32 /**
33 * Resizable-array implementation of the {@code List} interface. Implements
34 * all optional list operations, and permits all elements, including
35 * {@code null}. In addition to implementing the {@code List} interface,
36 * this class provides methods to manipulate the size of the array that is
37 * used internally to store the list. (This class is roughly equivalent to
38 * {@code Vector}, except that it is unsynchronized.)
39 *
40 * <p>The {@code size}, {@code isEmpty}, {@code get}, {@code set},
41 * {@code iterator}, and {@code listIterator} operations run in constant
42 * time. The {@code add} operation runs in <i>amortized constant time</i>,
43 * that is, adding n elements requires O(n) time. All of the other operations
44 * run in linear time (roughly speaking). The constant factor is low compared
45 * to that for the {@code LinkedList} implementation.
46 *
47 * <p>Each {@code ArrayList} instance has a <i>capacity</i>. The capacity is
48 * the size of the array used to store the elements in the list. It is always
49 * at least as large as the list size. As elements are added to an ArrayList,
50 * its capacity grows automatically. The details of the growth policy are not
51 * specified beyond the fact that adding an element has constant amortized
52 * time cost.
53 *
54 * <p>An application can increase the capacity of an {@code ArrayList} instance
55 * before adding a large number of elements using the {@code ensureCapacity}
56 * operation. This may reduce the amount of incremental reallocation.
57 *
58 * <p><strong>Note that this implementation is not synchronized.</strong>
59 * If multiple threads access an {@code ArrayList} instance concurrently,
60 * and at least one of the threads modifies the list structurally, it
61 * <i>must</i> be synchronized externally. (A structural modification is
62 * any operation that adds or deletes one or more elements, or explicitly
63 * resizes the backing array; merely setting the value of an element is not
64 * a structural modification.) This is typically accomplished by
65 * synchronizing on some object that naturally encapsulates the list.
66 *
67 * If no such object exists, the list should be "wrapped" using the
68 * {@link Collections#synchronizedList Collections.synchronizedList}
69 * method. This is best done at creation time, to prevent accidental
70 * unsynchronized access to the list:<pre>
71 * List list = Collections.synchronizedList(new ArrayList(...));</pre>
72 *
73 * <p id="fail-fast">
74 * The iterators returned by this class's {@link #iterator() iterator} and
75 * {@link #listIterator(int) listIterator} methods are <em>fail-fast</em>:
76 * if the list is structurally modified at any time after the iterator is
77 * created, in any way except through the iterator's own
78 * {@link ListIterator#remove() remove} or
79 * {@link ListIterator#add(Object) add} methods, the iterator will throw a
80 * {@link ConcurrentModificationException}. Thus, in the face of
81 * concurrent modification, the iterator fails quickly and cleanly, rather
82 * than risking arbitrary, non-deterministic behavior at an undetermined
83 * time in the future.
84 *
85 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
86 * as it is, generally speaking, impossible to make any hard guarantees in the
87 * presence of unsynchronized concurrent modification. Fail-fast iterators
88 * throw {@code ConcurrentModificationException} on a best-effort basis.
89 * Therefore, it would be wrong to write a program that depended on this
90 * exception for its correctness: <i>the fail-fast behavior of iterators
91 * should be used only to detect bugs.</i>
92 *
93 * <p>This class is a member of the
94 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
95 * Java Collections Framework</a>.
96 *
97 * @param <E> the type of elements in this list
98 *
99 * @author Josh Bloch
100 * @author Neal Gafter
101 * @see Collection
102 * @see List
103 * @see LinkedList
104 * @see Vector
105 * @since 1.2
106 */
107
108 public class ArrayList<E> extends AbstractList<E>
109 implements List<E>, RandomAccess, Cloneable, java.io.Serializable
110 {
111 private static final long serialVersionUID = 8683452581122892189L;
112
113 /**
114 * Default initial capacity.
115 */
116 private static final int DEFAULT_CAPACITY = 10;
117
118 /**
119 * Shared empty array instance used for empty instances.
120 */
121 private static final Object[] EMPTY_ELEMENTDATA = {};
122
123 /**
124 * Shared empty array instance used for default sized empty instances. We
125 * distinguish this from EMPTY_ELEMENTDATA to know how much to inflate when
126 * first element is added.
127 */
128 private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA = {};
129
130 /**
131 * The array buffer into which the elements of the ArrayList are stored.
132 * The capacity of the ArrayList is the length of this array buffer. Any
133 * empty ArrayList with elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
134 * will be expanded to DEFAULT_CAPACITY when the first element is added.
135 */
136 transient Object[] elementData; // non-private to simplify nested class access
137
138 /**
139 * The size of the ArrayList (the number of elements it contains).
140 *
141 * @serial
142 */
143 private int size;
144
145 /**
146 * Constructs an empty list with the specified initial capacity.
147 *
148 * @param initialCapacity the initial capacity of the list
149 * @throws IllegalArgumentException if the specified initial capacity
150 * is negative
151 */
152 public ArrayList(int initialCapacity) {
153 if (initialCapacity > 0) {
154 this.elementData = new Object[initialCapacity];
155 } else if (initialCapacity == 0) {
156 this.elementData = EMPTY_ELEMENTDATA;
157 } else {
158 throw new IllegalArgumentException("Illegal Capacity: "+
159 initialCapacity);
160 }
161 }
162
163 /**
164 * Constructs an empty list with an initial capacity of ten.
165 */
166 public ArrayList() {
167 this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
168 }
169
170 /**
171 * Constructs a list containing the elements of the specified
172 * collection, in the order they are returned by the collection's
173 * iterator.
174 *
175 * @param c the collection whose elements are to be placed into this list
176 * @throws NullPointerException if the specified collection is null
177 */
178 public ArrayList(Collection<? extends E> c) {
179 elementData = c.toArray();
180 if ((size = elementData.length) != 0) {
181 // defend against c.toArray (incorrectly) not returning Object[]
182 // (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652)
183 if (elementData.getClass() != Object[].class)
184 elementData = Arrays.copyOf(elementData, size, Object[].class);
185 } else {
186 // replace with empty array.
187 this.elementData = EMPTY_ELEMENTDATA;
188 }
189 }
190
191 /**
192 * Trims the capacity of this {@code ArrayList} instance to be the
193 * list's current size. An application can use this operation to minimize
194 * the storage of an {@code ArrayList} instance.
195 */
196 public void trimToSize() {
197 modCount++;
198 if (size < elementData.length) {
199 elementData = (size == 0)
200 ? EMPTY_ELEMENTDATA
201 : Arrays.copyOf(elementData, size);
202 }
203 }
204
205 /**
206 * Increases the capacity of this {@code ArrayList} instance, if
207 * necessary, to ensure that it can hold at least the number of elements
208 * specified by the minimum capacity argument.
209 *
210 * @param minCapacity the desired minimum capacity
211 */
212 public void ensureCapacity(int minCapacity) {
213 if (minCapacity > elementData.length
214 && !(elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
215 && minCapacity <= DEFAULT_CAPACITY)) {
216 modCount++;
217 grow(minCapacity);
218 }
219 }
220
221 /**
222 * The maximum size of array to allocate (unless necessary).
223 * Some VMs reserve some header words in an array.
224 * Attempts to allocate larger arrays may result in
225 * OutOfMemoryError: Requested array size exceeds VM limit
226 */
227 private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
228
229 /**
230 * Increases the capacity to ensure that it can hold at least the
231 * number of elements specified by the minimum capacity argument.
232 *
233 * @param minCapacity the desired minimum capacity
234 * @throws OutOfMemoryError if minCapacity is less than zero
235 */
236 private Object[] grow(int minCapacity) {
237 return elementData = Arrays.copyOf(elementData,
238 newCapacity(minCapacity));
239 }
240
241 private Object[] grow() {
242 return grow(size + 1);
243 }
244
245 /**
246 * Returns a capacity at least as large as the given minimum capacity.
247 * Returns the current capacity increased by 50% if that suffices.
248 * Will not return a capacity greater than MAX_ARRAY_SIZE unless
249 * the given minimum capacity is greater than MAX_ARRAY_SIZE.
250 *
251 * @param minCapacity the desired minimum capacity
252 * @throws OutOfMemoryError if minCapacity is less than zero
253 */
254 private int newCapacity(int minCapacity) {
255 // overflow-conscious code
256 int oldCapacity = elementData.length;
257 int newCapacity = oldCapacity + (oldCapacity >> 1);
258 if (newCapacity - minCapacity <= 0) {
259 if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA)
260 return Math.max(DEFAULT_CAPACITY, minCapacity);
261 if (minCapacity < 0) // overflow
262 throw new OutOfMemoryError();
263 return minCapacity;
264 }
265 return (newCapacity - MAX_ARRAY_SIZE <= 0)
266 ? newCapacity
267 : hugeCapacity(minCapacity);
268 }
269
270 private static int hugeCapacity(int minCapacity) {
271 if (minCapacity < 0) // overflow
272 throw new OutOfMemoryError();
273 return (minCapacity > MAX_ARRAY_SIZE)
274 ? Integer.MAX_VALUE
275 : MAX_ARRAY_SIZE;
276 }
277
278 /**
279 * Returns the number of elements in this list.
280 *
281 * @return the number of elements in this list
282 */
283 public int size() {
284 return size;
285 }
286
287 /**
288 * Returns {@code true} if this list contains no elements.
289 *
290 * @return {@code true} if this list contains no elements
291 */
292 public boolean isEmpty() {
293 return size == 0;
294 }
295
296 /**
297 * Returns {@code true} if this list contains the specified element.
298 * More formally, returns {@code true} if and only if this list contains
299 * at least one element {@code e} such that
300 * {@code Objects.equals(o, e)}.
301 *
302 * @param o element whose presence in this list is to be tested
303 * @return {@code true} if this list contains the specified element
304 */
305 public boolean contains(Object o) {
306 return indexOf(o) >= 0;
307 }
308
309 /**
310 * Returns the index of the first occurrence of the specified element
311 * in this list, or -1 if this list does not contain the element.
312 * More formally, returns the lowest index {@code i} such that
313 * {@code Objects.equals(o, get(i))},
314 * or -1 if there is no such index.
315 */
316 public int indexOf(Object o) {
317 if (o == null) {
318 for (int i = 0; i < size; i++)
319 if (elementData[i]==null)
320 return i;
321 } else {
322 for (int i = 0; i < size; i++)
323 if (o.equals(elementData[i]))
324 return i;
325 }
326 return -1;
327 }
328
329 /**
330 * Returns the index of the last occurrence of the specified element
331 * in this list, or -1 if this list does not contain the element.
332 * More formally, returns the highest index {@code i} such that
333 * {@code Objects.equals(o, get(i))},
334 * or -1 if there is no such index.
335 */
336 public int lastIndexOf(Object o) {
337 if (o == null) {
338 for (int i = size-1; i >= 0; i--)
339 if (elementData[i]==null)
340 return i;
341 } else {
342 for (int i = size-1; i >= 0; i--)
343 if (o.equals(elementData[i]))
344 return i;
345 }
346 return -1;
347 }
348
349 /**
350 * Returns a shallow copy of this {@code ArrayList} instance. (The
351 * elements themselves are not copied.)
352 *
353 * @return a clone of this {@code ArrayList} instance
354 */
355 public Object clone() {
356 try {
357 ArrayList<?> v = (ArrayList<?>) super.clone();
358 v.elementData = Arrays.copyOf(elementData, size);
359 v.modCount = 0;
360 return v;
361 } catch (CloneNotSupportedException e) {
362 // this shouldn't happen, since we are Cloneable
363 throw new InternalError(e);
364 }
365 }
366
367 /**
368 * Returns an array containing all of the elements in this list
369 * in proper sequence (from first to last element).
370 *
371 * <p>The returned array will be "safe" in that no references to it are
372 * maintained by this list. (In other words, this method must allocate
373 * a new array). The caller is thus free to modify the returned array.
374 *
375 * <p>This method acts as bridge between array-based and collection-based
376 * APIs.
377 *
378 * @return an array containing all of the elements in this list in
379 * proper sequence
380 */
381 public Object[] toArray() {
382 return Arrays.copyOf(elementData, size);
383 }
384
385 /**
386 * Returns an array containing all of the elements in this list in proper
387 * sequence (from first to last element); the runtime type of the returned
388 * array is that of the specified array. If the list fits in the
389 * specified array, it is returned therein. Otherwise, a new array is
390 * allocated with the runtime type of the specified array and the size of
391 * this list.
392 *
393 * <p>If the list fits in the specified array with room to spare
394 * (i.e., the array has more elements than the list), the element in
395 * the array immediately following the end of the collection is set to
396 * {@code null}. (This is useful in determining the length of the
397 * list <i>only</i> if the caller knows that the list does not contain
398 * any null elements.)
399 *
400 * @param a the array into which the elements of the list are to
401 * be stored, if it is big enough; otherwise, a new array of the
402 * same runtime type is allocated for this purpose.
403 * @return an array containing the elements of the list
404 * @throws ArrayStoreException if the runtime type of the specified array
405 * is not a supertype of the runtime type of every element in
406 * this list
407 * @throws NullPointerException if the specified array is null
408 */
409 @SuppressWarnings("unchecked")
410 public <T> T[] toArray(T[] a) {
411 if (a.length < size)
412 // Make a new array of a's runtime type, but my contents:
413 return (T[]) Arrays.copyOf(elementData, size, a.getClass());
414 System.arraycopy(elementData, 0, a, 0, size);
415 if (a.length > size)
416 a[size] = null;
417 return a;
418 }
419
420 // Positional Access Operations
421
422 @SuppressWarnings("unchecked")
423 E elementData(int index) {
424 return (E) elementData[index];
425 }
426
427 /**
428 * Returns the element at the specified position in this list.
429 *
430 * @param index index of the element to return
431 * @return the element at the specified position in this list
432 * @throws IndexOutOfBoundsException {@inheritDoc}
433 */
434 public E get(int index) {
435 rangeCheck(index);
436
437 return elementData(index);
438 }
439
440 /**
441 * Replaces the element at the specified position in this list with
442 * the specified element.
443 *
444 * @param index index of the element to replace
445 * @param element element to be stored at the specified position
446 * @return the element previously at the specified position
447 * @throws IndexOutOfBoundsException {@inheritDoc}
448 */
449 public E set(int index, E element) {
450 rangeCheck(index);
451
452 E oldValue = elementData(index);
453 elementData[index] = element;
454 return oldValue;
455 }
456
457 /**
458 * This helper method split out from add(E) to keep method
459 * bytecode size under 35 (the -XX:MaxInlineSize default value),
460 * which helps when add(E) is called in a C1-compiled loop.
461 */
462 private void add(E e, Object[] elementData, int s) {
463 if (s == elementData.length)
464 elementData = grow();
465 elementData[s] = e;
466 size = s + 1;
467 }
468
469 /**
470 * Appends the specified element to the end of this list.
471 *
472 * @param e element to be appended to this list
473 * @return {@code true} (as specified by {@link Collection#add})
474 */
475 public boolean add(E e) {
476 modCount++;
477 add(e, elementData, size);
478 return true;
479 }
480
481 /**
482 * Inserts the specified element at the specified position in this
483 * list. Shifts the element currently at that position (if any) and
484 * any subsequent elements to the right (adds one to their indices).
485 *
486 * @param index index at which the specified element is to be inserted
487 * @param element element to be inserted
488 * @throws IndexOutOfBoundsException {@inheritDoc}
489 */
490 public void add(int index, E element) {
491 rangeCheckForAdd(index);
492 modCount++;
493 final int s;
494 Object[] elementData;
495 if ((s = size) == (elementData = this.elementData).length)
496 elementData = grow();
497 System.arraycopy(elementData, index,
498 elementData, index + 1,
499 s - index);
500 elementData[index] = element;
501 size = s + 1;
502 }
503
504 /**
505 * Removes the element at the specified position in this list.
506 * Shifts any subsequent elements to the left (subtracts one from their
507 * indices).
508 *
509 * @param index the index of the element to be removed
510 * @return the element that was removed from the list
511 * @throws IndexOutOfBoundsException {@inheritDoc}
512 */
513 public E remove(int index) {
514 rangeCheck(index);
515
516 modCount++;
517 E oldValue = elementData(index);
518
519 int numMoved = size - index - 1;
520 if (numMoved > 0)
521 System.arraycopy(elementData, index+1, elementData, index,
522 numMoved);
523 elementData[--size] = null; // clear to let GC do its work
524
525 return oldValue;
526 }
527
528 /**
529 * Removes the first occurrence of the specified element from this list,
530 * if it is present. If the list does not contain the element, it is
531 * unchanged. More formally, removes the element with the lowest index
532 * {@code i} such that
533 * {@code Objects.equals(o, get(i))}
534 * (if such an element exists). Returns {@code true} if this list
535 * contained the specified element (or equivalently, if this list
536 * changed as a result of the call).
537 *
538 * @param o element to be removed from this list, if present
539 * @return {@code true} if this list contained the specified element
540 */
541 public boolean remove(Object o) {
542 if (o == null) {
543 for (int index = 0; index < size; index++)
544 if (elementData[index] == null) {
545 fastRemove(index);
546 return true;
547 }
548 } else {
549 for (int index = 0; index < size; index++)
550 if (o.equals(elementData[index])) {
551 fastRemove(index);
552 return true;
553 }
554 }
555 return false;
556 }
557
558 /*
559 * Private remove method that skips bounds checking and does not
560 * return the value removed.
561 */
562 private void fastRemove(int index) {
563 modCount++;
564 int numMoved = size - index - 1;
565 if (numMoved > 0)
566 System.arraycopy(elementData, index+1, elementData, index,
567 numMoved);
568 elementData[--size] = null; // clear to let GC do its work
569 }
570
571 /**
572 * Removes all of the elements from this list. The list will
573 * be empty after this call returns.
574 */
575 public void clear() {
576 modCount++;
577
578 // clear to let GC do its work
579 for (int i = 0; i < size; i++)
580 elementData[i] = null;
581
582 size = 0;
583 }
584
585 /**
586 * Appends all of the elements in the specified collection to the end of
587 * this list, in the order that they are returned by the
588 * specified collection's Iterator. The behavior of this operation is
589 * undefined if the specified collection is modified while the operation
590 * is in progress. (This implies that the behavior of this call is
591 * undefined if the specified collection is this list, and this
592 * list is nonempty.)
593 *
594 * @param c collection containing elements to be added to this list
595 * @return {@code true} if this list changed as a result of the call
596 * @throws NullPointerException if the specified collection is null
597 */
598 public boolean addAll(Collection<? extends E> c) {
599 Object[] a = c.toArray();
600 modCount++;
601 int numNew = a.length;
602 if (numNew == 0)
603 return false;
604 Object[] elementData;
605 final int s;
606 if (numNew > (elementData = this.elementData).length - (s = size))
607 elementData = grow(s + numNew);
608 System.arraycopy(a, 0, elementData, s, numNew);
609 size = s + numNew;
610 return true;
611 }
612
613 /**
614 * Inserts all of the elements in the specified collection into this
615 * list, starting at the specified position. Shifts the element
616 * currently at that position (if any) and any subsequent elements to
617 * the right (increases their indices). The new elements will appear
618 * in the list in the order that they are returned by the
619 * specified collection's iterator.
620 *
621 * @param index index at which to insert the first element from the
622 * specified collection
623 * @param c collection containing elements to be added to this list
624 * @return {@code true} if this list changed as a result of the call
625 * @throws IndexOutOfBoundsException {@inheritDoc}
626 * @throws NullPointerException if the specified collection is null
627 */
628 public boolean addAll(int index, Collection<? extends E> c) {
629 rangeCheckForAdd(index);
630
631 Object[] a = c.toArray();
632 modCount++;
633 int numNew = a.length;
634 if (numNew == 0)
635 return false;
636 Object[] elementData;
637 final int s;
638 if (numNew > (elementData = this.elementData).length - (s = size))
639 elementData = grow(s + numNew);
640
641 int numMoved = s - index;
642 if (numMoved > 0)
643 System.arraycopy(elementData, index,
644 elementData, index + numNew,
645 numMoved);
646 System.arraycopy(a, 0, elementData, index, numNew);
647 size = s + numNew;
648 return true;
649 }
650
651 /**
652 * Removes from this list all of the elements whose index is between
653 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
654 * Shifts any succeeding elements to the left (reduces their index).
655 * This call shortens the list by {@code (toIndex - fromIndex)} elements.
656 * (If {@code toIndex==fromIndex}, this operation has no effect.)
657 *
658 * @throws IndexOutOfBoundsException if {@code fromIndex} or
659 * {@code toIndex} is out of range
660 * ({@code fromIndex < 0 ||
661 * toIndex > size() ||
662 * toIndex < fromIndex})
663 */
664 protected void removeRange(int fromIndex, int toIndex) {
665 if (fromIndex > toIndex) {
666 throw new IndexOutOfBoundsException(
667 outOfBoundsMsg(fromIndex, toIndex));
668 }
669 modCount++;
670 int numMoved = size - toIndex;
671 System.arraycopy(elementData, toIndex, elementData, fromIndex,
672 numMoved);
673
674 // clear to let GC do its work
675 int newSize = size - (toIndex-fromIndex);
676 for (int i = newSize; i < size; i++) {
677 elementData[i] = null;
678 }
679 size = newSize;
680 }
681
682 /**
683 * Checks if the given index is in range. If not, throws an appropriate
684 * runtime exception. This method does *not* check if the index is
685 * negative: It is always used immediately prior to an array access,
686 * which throws an ArrayIndexOutOfBoundsException if index is negative.
687 */
688 private void rangeCheck(int index) {
689 if (index >= size)
690 throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
691 }
692
693 /**
694 * A version of rangeCheck used by add and addAll.
695 */
696 private void rangeCheckForAdd(int index) {
697 if (index > size || index < 0)
698 throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
699 }
700
701 /**
702 * Constructs an IndexOutOfBoundsException detail message.
703 * Of the many possible refactorings of the error handling code,
704 * this "outlining" performs best with both server and client VMs.
705 */
706 private String outOfBoundsMsg(int index) {
707 return "Index: " + index + ", Size: " + size;
708 }
709
710 /**
711 * A version used in checking (fromIndex > toIndex) condition
712 */
713 private static String outOfBoundsMsg(int fromIndex, int toIndex) {
714 return "From Index: " + fromIndex + " > To Index: " + toIndex;
715 }
716
717 /**
718 * Removes from this list all of its elements that are contained in the
719 * specified collection.
720 *
721 * @param c collection containing elements to be removed from this list
722 * @return {@code true} if this list changed as a result of the call
723 * @throws ClassCastException if the class of an element of this list
724 * is incompatible with the specified collection
725 * (<a href="Collection.html#optional-restrictions">optional</a>)
726 * @throws NullPointerException if this list contains a null element and the
727 * specified collection does not permit null elements
728 * (<a href="Collection.html#optional-restrictions">optional</a>),
729 * or if the specified collection is null
730 * @see Collection#contains(Object)
731 */
732 public boolean removeAll(Collection<?> c) {
733 Objects.requireNonNull(c);
734 return batchRemove(c, false);
735 }
736
737 /**
738 * Retains only the elements in this list that are contained in the
739 * specified collection. In other words, removes from this list all
740 * of its elements that are not contained in the specified collection.
741 *
742 * @param c collection containing elements to be retained in this list
743 * @return {@code true} if this list changed as a result of the call
744 * @throws ClassCastException if the class of an element of this list
745 * is incompatible with the specified collection
746 * (<a href="Collection.html#optional-restrictions">optional</a>)
747 * @throws NullPointerException if this list contains a null element and the
748 * specified collection does not permit null elements
749 * (<a href="Collection.html#optional-restrictions">optional</a>),
750 * or if the specified collection is null
751 * @see Collection#contains(Object)
752 */
753 public boolean retainAll(Collection<?> c) {
754 Objects.requireNonNull(c);
755 return batchRemove(c, true);
756 }
757
758 private boolean batchRemove(Collection<?> c, boolean complement) {
759 final Object[] elementData = this.elementData;
760 int r = 0, w = 0;
761 boolean modified = false;
762 try {
763 for (; r < size; r++)
764 if (c.contains(elementData[r]) == complement)
765 elementData[w++] = elementData[r];
766 } finally {
767 // Preserve behavioral compatibility with AbstractCollection,
768 // even if c.contains() throws.
769 if (r != size) {
770 System.arraycopy(elementData, r,
771 elementData, w,
772 size - r);
773 w += size - r;
774 }
775 if (w != size) {
776 // clear to let GC do its work
777 for (int i = w; i < size; i++)
778 elementData[i] = null;
779 modCount += size - w;
780 size = w;
781 modified = true;
782 }
783 }
784 return modified;
785 }
786
787 /**
788 * Save the state of the {@code ArrayList} instance to a stream (that
789 * is, serialize it).
790 *
791 * @serialData The length of the array backing the {@code ArrayList}
792 * instance is emitted (int), followed by all of its elements
793 * (each an {@code Object}) in the proper order.
794 */
795 private void writeObject(java.io.ObjectOutputStream s)
796 throws java.io.IOException{
797 // Write out element count, and any hidden stuff
798 int expectedModCount = modCount;
799 s.defaultWriteObject();
800
801 // Write out size as capacity for behavioural compatibility with clone()
802 s.writeInt(size);
803
804 // Write out all elements in the proper order.
805 for (int i=0; i<size; i++) {
806 s.writeObject(elementData[i]);
807 }
808
809 if (modCount != expectedModCount) {
810 throw new ConcurrentModificationException();
811 }
812 }
813
814 /**
815 * Reconstitute the {@code ArrayList} instance from a stream (that is,
816 * deserialize it).
817 */
818 private void readObject(java.io.ObjectInputStream s)
819 throws java.io.IOException, ClassNotFoundException {
820
821 // Read in size, and any hidden stuff
822 s.defaultReadObject();
823
824 // Read in capacity
825 s.readInt(); // ignored
826
827 if (size > 0) {
828 // like clone(), allocate array based upon size not capacity
829 Object[] elements = new Object[size];
830
831 // Read in all elements in the proper order.
832 for (int i = 0; i < size; i++) {
833 elements[i] = s.readObject();
834 }
835
836 elementData = elements;
837 } else if (size == 0) {
838 elementData = EMPTY_ELEMENTDATA;
839 } else {
840 throw new java.io.InvalidObjectException("Invalid size: " + size);
841 }
842 }
843
844 /**
845 * Returns a list iterator over the elements in this list (in proper
846 * sequence), starting at the specified position in the list.
847 * The specified index indicates the first element that would be
848 * returned by an initial call to {@link ListIterator#next next}.
849 * An initial call to {@link ListIterator#previous previous} would
850 * return the element with the specified index minus one.
851 *
852 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
853 *
854 * @throws IndexOutOfBoundsException {@inheritDoc}
855 */
856 public ListIterator<E> listIterator(int index) {
857 if (index < 0 || index > size)
858 throw new IndexOutOfBoundsException("Index: "+index);
859 return new ListItr(index);
860 }
861
862 /**
863 * Returns a list iterator over the elements in this list (in proper
864 * sequence).
865 *
866 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
867 *
868 * @see #listIterator(int)
869 */
870 public ListIterator<E> listIterator() {
871 return new ListItr(0);
872 }
873
874 /**
875 * Returns an iterator over the elements in this list in proper sequence.
876 *
877 * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
878 *
879 * @return an iterator over the elements in this list in proper sequence
880 */
881 public Iterator<E> iterator() {
882 return new Itr();
883 }
884
885 /**
886 * An optimized version of AbstractList.Itr
887 */
888 private class Itr implements Iterator<E> {
889 int cursor; // index of next element to return
890 int lastRet = -1; // index of last element returned; -1 if no such
891 int expectedModCount = modCount;
892
893 public boolean hasNext() {
894 return cursor != size;
895 }
896
897 @SuppressWarnings("unchecked")
898 public E next() {
899 checkForComodification();
900 int i = cursor;
901 if (i >= size)
902 throw new NoSuchElementException();
903 Object[] elementData = ArrayList.this.elementData;
904 if (i >= elementData.length)
905 throw new ConcurrentModificationException();
906 cursor = i + 1;
907 return (E) elementData[lastRet = i];
908 }
909
910 public void remove() {
911 if (lastRet < 0)
912 throw new IllegalStateException();
913 checkForComodification();
914
915 try {
916 ArrayList.this.remove(lastRet);
917 cursor = lastRet;
918 lastRet = -1;
919 expectedModCount = modCount;
920 } catch (IndexOutOfBoundsException ex) {
921 throw new ConcurrentModificationException();
922 }
923 }
924
925 @Override
926 @SuppressWarnings("unchecked")
927 public void forEachRemaining(Consumer<? super E> consumer) {
928 Objects.requireNonNull(consumer);
929 final int size = ArrayList.this.size;
930 int i = cursor;
931 if (i >= size) {
932 return;
933 }
934 final Object[] elementData = ArrayList.this.elementData;
935 if (i >= elementData.length) {
936 throw new ConcurrentModificationException();
937 }
938 while (i != size && modCount == expectedModCount) {
939 consumer.accept((E) elementData[i++]);
940 }
941 // update once at end of iteration to reduce heap write traffic
942 cursor = i;
943 lastRet = i - 1;
944 checkForComodification();
945 }
946
947 final void checkForComodification() {
948 if (modCount != expectedModCount)
949 throw new ConcurrentModificationException();
950 }
951 }
952
953 /**
954 * An optimized version of AbstractList.ListItr
955 */
956 private class ListItr extends Itr implements ListIterator<E> {
957 ListItr(int index) {
958 super();
959 cursor = index;
960 }
961
962 public boolean hasPrevious() {
963 return cursor != 0;
964 }
965
966 public int nextIndex() {
967 return cursor;
968 }
969
970 public int previousIndex() {
971 return cursor - 1;
972 }
973
974 @SuppressWarnings("unchecked")
975 public E previous() {
976 checkForComodification();
977 int i = cursor - 1;
978 if (i < 0)
979 throw new NoSuchElementException();
980 Object[] elementData = ArrayList.this.elementData;
981 if (i >= elementData.length)
982 throw new ConcurrentModificationException();
983 cursor = i;
984 return (E) elementData[lastRet = i];
985 }
986
987 public void set(E e) {
988 if (lastRet < 0)
989 throw new IllegalStateException();
990 checkForComodification();
991
992 try {
993 ArrayList.this.set(lastRet, e);
994 } catch (IndexOutOfBoundsException ex) {
995 throw new ConcurrentModificationException();
996 }
997 }
998
999 public void add(E e) {
1000 checkForComodification();
1001
1002 try {
1003 int i = cursor;
1004 ArrayList.this.add(i, e);
1005 cursor = i + 1;
1006 lastRet = -1;
1007 expectedModCount = modCount;
1008 } catch (IndexOutOfBoundsException ex) {
1009 throw new ConcurrentModificationException();
1010 }
1011 }
1012 }
1013
1014 /**
1015 * Returns a view of the portion of this list between the specified
1016 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. (If
1017 * {@code fromIndex} and {@code toIndex} are equal, the returned list is
1018 * empty.) The returned list is backed by this list, so non-structural
1019 * changes in the returned list are reflected in this list, and vice-versa.
1020 * The returned list supports all of the optional list operations.
1021 *
1022 * <p>This method eliminates the need for explicit range operations (of
1023 * the sort that commonly exist for arrays). Any operation that expects
1024 * a list can be used as a range operation by passing a subList view
1025 * instead of a whole list. For example, the following idiom
1026 * removes a range of elements from a list:
1027 * <pre>
1028 * list.subList(from, to).clear();
1029 * </pre>
1030 * Similar idioms may be constructed for {@link #indexOf(Object)} and
1031 * {@link #lastIndexOf(Object)}, and all of the algorithms in the
1032 * {@link Collections} class can be applied to a subList.
1033 *
1034 * <p>The semantics of the list returned by this method become undefined if
1035 * the backing list (i.e., this list) is <i>structurally modified</i> in
1036 * any way other than via the returned list. (Structural modifications are
1037 * those that change the size of this list, or otherwise perturb it in such
1038 * a fashion that iterations in progress may yield incorrect results.)
1039 *
1040 * @throws IndexOutOfBoundsException {@inheritDoc}
1041 * @throws IllegalArgumentException {@inheritDoc}
1042 */
1043 public List<E> subList(int fromIndex, int toIndex) {
1044 subListRangeCheck(fromIndex, toIndex, size);
1045 return new SubList<>(this, fromIndex, toIndex);
1046 }
1047
1048 private static class SubList<E> extends AbstractList<E> implements RandomAccess {
1049 private final ArrayList<E> root;
1050 private final SubList<E> parent;
1051 private final int offset;
1052 private int size;
1053
1054 /**
1055 * Constructs a sublist of an arbitrary ArrayList.
1056 */
1057 public SubList(ArrayList<E> root, int fromIndex, int toIndex) {
1058 this.root = root;
1059 this.parent = null;
1060 this.offset = fromIndex;
1061 this.size = toIndex - fromIndex;
1062 this.modCount = root.modCount;
1063 }
1064
1065 /**
1066 * Constructs a sublist of another SubList.
1067 */
1068 private SubList(SubList<E> parent, int fromIndex, int toIndex) {
1069 this.root = parent.root;
1070 this.parent = parent;
1071 this.offset = parent.offset + fromIndex;
1072 this.size = toIndex - fromIndex;
1073 this.modCount = root.modCount;
1074 }
1075
1076 public E set(int index, E element) {
1077 rangeCheck(index);
1078 checkForComodification();
1079 E oldValue = root.elementData(offset + index);
1080 root.elementData[offset + index] = element;
1081 return oldValue;
1082 }
1083
1084 public E get(int index) {
1085 rangeCheck(index);
1086 checkForComodification();
1087 return root.elementData(offset + index);
1088 }
1089
1090 public int size() {
1091 checkForComodification();
1092 return size;
1093 }
1094
1095 public void add(int index, E element) {
1096 rangeCheckForAdd(index);
1097 checkForComodification();
1098 root.add(offset + index, element);
1099 updateSizeAndModCount(1);
1100 }
1101
1102 public E remove(int index) {
1103 rangeCheck(index);
1104 checkForComodification();
1105 E result = root.remove(offset + index);
1106 updateSizeAndModCount(-1);
1107 return result;
1108 }
1109
1110 protected void removeRange(int fromIndex, int toIndex) {
1111 checkForComodification();
1112 root.removeRange(offset + fromIndex, offset + toIndex);
1113 updateSizeAndModCount(fromIndex - toIndex);
1114 }
1115
1116 public boolean addAll(Collection<? extends E> c) {
1117 return addAll(this.size, c);
1118 }
1119
1120 public boolean addAll(int index, Collection<? extends E> c) {
1121 rangeCheckForAdd(index);
1122 int cSize = c.size();
1123 if (cSize == 0)
1124 return false;
1125 checkForComodification();
1126 root.addAll(offset + index, c);
1127 updateSizeAndModCount(cSize);
1128 return true;
1129 }
1130
1131 public Iterator<E> iterator() {
1132 return listIterator();
1133 }
1134
1135 public ListIterator<E> listIterator(int index) {
1136 checkForComodification();
1137 rangeCheckForAdd(index);
1138
1139 return new ListIterator<E>() {
1140 int cursor = index;
1141 int lastRet = -1;
1142 int expectedModCount = root.modCount;
1143
1144 public boolean hasNext() {
1145 return cursor != SubList.this.size;
1146 }
1147
1148 @SuppressWarnings("unchecked")
1149 public E next() {
1150 checkForComodification();
1151 int i = cursor;
1152 if (i >= SubList.this.size)
1153 throw new NoSuchElementException();
1154 Object[] elementData = root.elementData;
1155 if (offset + i >= elementData.length)
1156 throw new ConcurrentModificationException();
1157 cursor = i + 1;
1158 return (E) elementData[offset + (lastRet = i)];
1159 }
1160
1161 public boolean hasPrevious() {
1162 return cursor != 0;
1163 }
1164
1165 @SuppressWarnings("unchecked")
1166 public E previous() {
1167 checkForComodification();
1168 int i = cursor - 1;
1169 if (i < 0)
1170 throw new NoSuchElementException();
1171 Object[] elementData = root.elementData;
1172 if (offset + i >= elementData.length)
1173 throw new ConcurrentModificationException();
1174 cursor = i;
1175 return (E) elementData[offset + (lastRet = i)];
1176 }
1177
1178 @SuppressWarnings("unchecked")
1179 public void forEachRemaining(Consumer<? super E> consumer) {
1180 Objects.requireNonNull(consumer);
1181 final int size = SubList.this.size;
1182 int i = cursor;
1183 if (i >= size) {
1184 return;
1185 }
1186 final Object[] elementData = root.elementData;
1187 if (offset + i >= elementData.length) {
1188 throw new ConcurrentModificationException();
1189 }
1190 while (i != size && modCount == expectedModCount) {
1191 consumer.accept((E) elementData[offset + (i++)]);
1192 }
1193 // update once at end of iteration to reduce heap write traffic
1194 lastRet = cursor = i;
1195 checkForComodification();
1196 }
1197
1198 public int nextIndex() {
1199 return cursor;
1200 }
1201
1202 public int previousIndex() {
1203 return cursor - 1;
1204 }
1205
1206 public void remove() {
1207 if (lastRet < 0)
1208 throw new IllegalStateException();
1209 checkForComodification();
1210
1211 try {
1212 SubList.this.remove(lastRet);
1213 cursor = lastRet;
1214 lastRet = -1;
1215 expectedModCount = root.modCount;
1216 } catch (IndexOutOfBoundsException ex) {
1217 throw new ConcurrentModificationException();
1218 }
1219 }
1220
1221 public void set(E e) {
1222 if (lastRet < 0)
1223 throw new IllegalStateException();
1224 checkForComodification();
1225
1226 try {
1227 root.set(offset + lastRet, e);
1228 } catch (IndexOutOfBoundsException ex) {
1229 throw new ConcurrentModificationException();
1230 }
1231 }
1232
1233 public void add(E e) {
1234 checkForComodification();
1235
1236 try {
1237 int i = cursor;
1238 SubList.this.add(i, e);
1239 cursor = i + 1;
1240 lastRet = -1;
1241 expectedModCount = root.modCount;
1242 } catch (IndexOutOfBoundsException ex) {
1243 throw new ConcurrentModificationException();
1244 }
1245 }
1246
1247 final void checkForComodification() {
1248 if (root.modCount != expectedModCount)
1249 throw new ConcurrentModificationException();
1250 }
1251 };
1252 }
1253
1254 public List<E> subList(int fromIndex, int toIndex) {
1255 subListRangeCheck(fromIndex, toIndex, size);
1256 return new SubList<>(this, fromIndex, toIndex);
1257 }
1258
1259 private void rangeCheck(int index) {
1260 if (index < 0 || index >= size)
1261 throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1262 }
1263
1264 private void rangeCheckForAdd(int index) {
1265 if (index < 0 || index > size)
1266 throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1267 }
1268
1269 private String outOfBoundsMsg(int index) {
1270 return "Index: " + index + ", Size: " + size;
1271 }
1272
1273 private void checkForComodification() {
1274 if (root.modCount != modCount)
1275 throw new ConcurrentModificationException();
1276 }
1277
1278 private void updateSizeAndModCount(int sizeChange) {
1279 SubList<E> slist = this;
1280 do {
1281 slist.size += sizeChange;
1282 slist.modCount = root.modCount;
1283 slist = slist.parent;
1284 } while (slist != null);
1285 }
1286
1287 public Spliterator<E> spliterator() {
1288 checkForComodification();
1289 return new ArrayListSpliterator<>(root, offset,
1290 offset + size, modCount);
1291 }
1292 }
1293
1294 @Override
1295 public void forEach(Consumer<? super E> action) {
1296 Objects.requireNonNull(action);
1297 final int expectedModCount = modCount;
1298 @SuppressWarnings("unchecked")
1299 final E[] elementData = (E[]) this.elementData;
1300 final int size = this.size;
1301 for (int i=0; modCount == expectedModCount && i < size; i++) {
1302 action.accept(elementData[i]);
1303 }
1304 if (modCount != expectedModCount) {
1305 throw new ConcurrentModificationException();
1306 }
1307 }
1308
1309 /**
1310 * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
1311 * and <em>fail-fast</em> {@link Spliterator} over the elements in this
1312 * list.
1313 *
1314 * <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
1315 * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}.
1316 * Overriding implementations should document the reporting of additional
1317 * characteristic values.
1318 *
1319 * @return a {@code Spliterator} over the elements in this list
1320 * @since 1.8
1321 */
1322 @Override
1323 public Spliterator<E> spliterator() {
1324 return new ArrayListSpliterator<>(this, 0, -1, 0);
1325 }
1326
1327 /** Index-based split-by-two, lazily initialized Spliterator */
1328 static final class ArrayListSpliterator<E> implements Spliterator<E> {
1329
1330 /*
1331 * If ArrayLists were immutable, or structurally immutable (no
1332 * adds, removes, etc), we could implement their spliterators
1333 * with Arrays.spliterator. Instead we detect as much
1334 * interference during traversal as practical without
1335 * sacrificing much performance. We rely primarily on
1336 * modCounts. These are not guaranteed to detect concurrency
1337 * violations, and are sometimes overly conservative about
1338 * within-thread interference, but detect enough problems to
1339 * be worthwhile in practice. To carry this out, we (1) lazily
1340 * initialize fence and expectedModCount until the latest
1341 * point that we need to commit to the state we are checking
1342 * against; thus improving precision. (This doesn't apply to
1343 * SubLists, that create spliterators with current non-lazy
1344 * values). (2) We perform only a single
1345 * ConcurrentModificationException check at the end of forEach
1346 * (the most performance-sensitive method). When using forEach
1347 * (as opposed to iterators), we can normally only detect
1348 * interference after actions, not before. Further
1349 * CME-triggering checks apply to all other possible
1350 * violations of assumptions for example null or too-small
1351 * elementData array given its size(), that could only have
1352 * occurred due to interference. This allows the inner loop
1353 * of forEach to run without any further checks, and
1354 * simplifies lambda-resolution. While this does entail a
1355 * number of checks, note that in the common case of
1356 * list.stream().forEach(a), no checks or other computation
1357 * occur anywhere other than inside forEach itself. The other
1358 * less-often-used methods cannot take advantage of most of
1359 * these streamlinings.
1360 */
1361
1362 private final ArrayList<E> list;
1363 private int index; // current index, modified on advance/split
1364 private int fence; // -1 until used; then one past last index
1365 private int expectedModCount; // initialized when fence set
1366
1367 /** Create new spliterator covering the given range */
1368 ArrayListSpliterator(ArrayList<E> list, int origin, int fence,
1369 int expectedModCount) {
1370 this.list = list; // OK if null unless traversed
1371 this.index = origin;
1372 this.fence = fence;
1373 this.expectedModCount = expectedModCount;
1374 }
1375
1376 private int getFence() { // initialize fence to size on first use
1377 int hi; // (a specialized variant appears in method forEach)
1378 ArrayList<E> lst;
1379 if ((hi = fence) < 0) {
1380 if ((lst = list) == null)
1381 hi = fence = 0;
1382 else {
1383 expectedModCount = lst.modCount;
1384 hi = fence = lst.size;
1385 }
1386 }
1387 return hi;
1388 }
1389
1390 public ArrayListSpliterator<E> trySplit() {
1391 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1392 return (lo >= mid) ? null : // divide range in half unless too small
1393 new ArrayListSpliterator<>(list, lo, index = mid,
1394 expectedModCount);
1395 }
1396
1397 public boolean tryAdvance(Consumer<? super E> action) {
1398 if (action == null)
1399 throw new NullPointerException();
1400 int hi = getFence(), i = index;
1401 if (i < hi) {
1402 index = i + 1;
1403 @SuppressWarnings("unchecked") E e = (E)list.elementData[i];
1404 action.accept(e);
1405 if (list.modCount != expectedModCount)
1406 throw new ConcurrentModificationException();
1407 return true;
1408 }
1409 return false;
1410 }
1411
1412 public void forEachRemaining(Consumer<? super E> action) {
1413 int i, hi, mc; // hoist accesses and checks from loop
1414 ArrayList<E> lst; Object[] a;
1415 if (action == null)
1416 throw new NullPointerException();
1417 if ((lst = list) != null && (a = lst.elementData) != null) {
1418 if ((hi = fence) < 0) {
1419 mc = lst.modCount;
1420 hi = lst.size;
1421 }
1422 else
1423 mc = expectedModCount;
1424 if ((i = index) >= 0 && (index = hi) <= a.length) {
1425 for (; i < hi; ++i) {
1426 @SuppressWarnings("unchecked") E e = (E) a[i];
1427 action.accept(e);
1428 }
1429 if (lst.modCount == mc)
1430 return;
1431 }
1432 }
1433 throw new ConcurrentModificationException();
1434 }
1435
1436 public long estimateSize() {
1437 return (long) (getFence() - index);
1438 }
1439
1440 public int characteristics() {
1441 return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
1442 }
1443 }
1444
1445 @Override
1446 public boolean removeIf(Predicate<? super E> filter) {
1447 Objects.requireNonNull(filter);
1448 // figure out which elements are to be removed
1449 // any exception thrown from the filter predicate at this stage
1450 // will leave the collection unmodified
1451 int removeCount = 0;
1452 final BitSet removeSet = new BitSet(size);
1453 final int expectedModCount = modCount;
1454 final int size = this.size;
1455 for (int i=0; modCount == expectedModCount && i < size; i++) {
1456 @SuppressWarnings("unchecked")
1457 final E element = (E) elementData[i];
1458 if (filter.test(element)) {
1459 removeSet.set(i);
1460 removeCount++;
1461 }
1462 }
1463 if (modCount != expectedModCount) {
1464 throw new ConcurrentModificationException();
1465 }
1466
1467 // shift surviving elements left over the spaces left by removed elements
1468 final boolean anyToRemove = removeCount > 0;
1469 if (anyToRemove) {
1470 final int newSize = size - removeCount;
1471 for (int i=0, j=0; (i < size) && (j < newSize); i++, j++) {
1472 i = removeSet.nextClearBit(i);
1473 elementData[j] = elementData[i];
1474 }
1475 for (int k=newSize; k < size; k++) {
1476 elementData[k] = null; // Let gc do its work
1477 }
1478 this.size = newSize;
1479 if (modCount != expectedModCount) {
1480 throw new ConcurrentModificationException();
1481 }
1482 modCount++;
1483 }
1484
1485 return anyToRemove;
1486 }
1487
1488 @Override
1489 @SuppressWarnings("unchecked")
1490 public void replaceAll(UnaryOperator<E> operator) {
1491 Objects.requireNonNull(operator);
1492 final int expectedModCount = modCount;
1493 final int size = this.size;
1494 for (int i=0; modCount == expectedModCount && i < size; i++) {
1495 elementData[i] = operator.apply((E) elementData[i]);
1496 }
1497 if (modCount != expectedModCount) {
1498 throw new ConcurrentModificationException();
1499 }
1500 modCount++;
1501 }
1502
1503 @Override
1504 @SuppressWarnings("unchecked")
1505 public void sort(Comparator<? super E> c) {
1506 final int expectedModCount = modCount;
1507 Arrays.sort((E[]) elementData, 0, size, c);
1508 if (modCount != expectedModCount) {
1509 throw new ConcurrentModificationException();
1510 }
1511 modCount++;
1512 }
1513 }