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 Objects.checkIndex(index, size);
436 return elementData(index);
437 }
438
439 /**
440 * Replaces the element at the specified position in this list with
441 * the specified element.
442 *
443 * @param index index of the element to replace
444 * @param element element to be stored at the specified position
445 * @return the element previously at the specified position
446 * @throws IndexOutOfBoundsException {@inheritDoc}
447 */
448 public E set(int index, E element) {
449 Objects.checkIndex(index, size);
450 E oldValue = elementData(index);
451 elementData[index] = element;
452 return oldValue;
453 }
454
455 /**
456 * This helper method split out from add(E) to keep method
457 * bytecode size under 35 (the -XX:MaxInlineSize default value),
458 * which helps when add(E) is called in a C1-compiled loop.
459 */
460 private void add(E e, Object[] elementData, int s) {
461 if (s == elementData.length)
462 elementData = grow();
463 elementData[s] = e;
464 size = s + 1;
465 }
466
467 /**
468 * Appends the specified element to the end of this list.
469 *
470 * @param e element to be appended to this list
471 * @return {@code true} (as specified by {@link Collection#add})
472 */
473 public boolean add(E e) {
474 modCount++;
475 add(e, elementData, size);
476 return true;
477 }
478
479 /**
480 * Inserts the specified element at the specified position in this
481 * list. Shifts the element currently at that position (if any) and
482 * any subsequent elements to the right (adds one to their indices).
483 *
484 * @param index index at which the specified element is to be inserted
485 * @param element element to be inserted
486 * @throws IndexOutOfBoundsException {@inheritDoc}
487 */
488 public void add(int index, E element) {
489 rangeCheckForAdd(index);
490 modCount++;
491 final int s;
492 Object[] elementData;
493 if ((s = size) == (elementData = this.elementData).length)
494 elementData = grow();
495 System.arraycopy(elementData, index,
496 elementData, index + 1,
497 s - index);
498 elementData[index] = element;
499 size = s + 1;
500 }
501
502 /**
503 * Removes the element at the specified position in this list.
504 * Shifts any subsequent elements to the left (subtracts one from their
505 * indices).
506 *
507 * @param index the index of the element to be removed
508 * @return the element that was removed from the list
509 * @throws IndexOutOfBoundsException {@inheritDoc}
510 */
511 public E remove(int index) {
512 Objects.checkIndex(index, size);
513
514 modCount++;
515 E oldValue = elementData(index);
516
517 int numMoved = size - index - 1;
518 if (numMoved > 0)
519 System.arraycopy(elementData, index+1, elementData, index,
520 numMoved);
521 elementData[--size] = null; // clear to let GC do its work
522
523 return oldValue;
524 }
525
526 /**
527 * Removes the first occurrence of the specified element from this list,
528 * if it is present. If the list does not contain the element, it is
529 * unchanged. More formally, removes the element with the lowest index
530 * {@code i} such that
531 * {@code Objects.equals(o, get(i))}
532 * (if such an element exists). Returns {@code true} if this list
533 * contained the specified element (or equivalently, if this list
534 * changed as a result of the call).
535 *
536 * @param o element to be removed from this list, if present
537 * @return {@code true} if this list contained the specified element
538 */
539 public boolean remove(Object o) {
540 if (o == null) {
541 for (int index = 0; index < size; index++)
542 if (elementData[index] == null) {
543 fastRemove(index);
544 return true;
545 }
546 } else {
547 for (int index = 0; index < size; index++)
548 if (o.equals(elementData[index])) {
549 fastRemove(index);
550 return true;
551 }
552 }
553 return false;
554 }
555
556 /*
557 * Private remove method that skips bounds checking and does not
558 * return the value removed.
559 */
560 private void fastRemove(int index) {
561 modCount++;
562 int numMoved = size - index - 1;
563 if (numMoved > 0)
564 System.arraycopy(elementData, index+1, elementData, index,
565 numMoved);
566 elementData[--size] = null; // clear to let GC do its work
567 }
568
569 /**
570 * Removes all of the elements from this list. The list will
571 * be empty after this call returns.
572 */
573 public void clear() {
574 modCount++;
575
576 // clear to let GC do its work
577 for (int i = 0; i < size; i++)
578 elementData[i] = null;
579
580 size = 0;
581 }
582
583 /**
584 * Appends all of the elements in the specified collection to the end of
585 * this list, in the order that they are returned by the
586 * specified collection's Iterator. The behavior of this operation is
587 * undefined if the specified collection is modified while the operation
588 * is in progress. (This implies that the behavior of this call is
589 * undefined if the specified collection is this list, and this
590 * list is nonempty.)
591 *
592 * @param c collection containing elements to be added to this list
593 * @return {@code true} if this list changed as a result of the call
594 * @throws NullPointerException if the specified collection is null
595 */
596 public boolean addAll(Collection<? extends E> c) {
597 Object[] a = c.toArray();
598 modCount++;
599 int numNew = a.length;
600 if (numNew == 0)
601 return false;
602 Object[] elementData;
603 final int s;
604 if (numNew > (elementData = this.elementData).length - (s = size))
605 elementData = grow(s + numNew);
606 System.arraycopy(a, 0, elementData, s, numNew);
607 size = s + numNew;
608 return true;
609 }
610
611 /**
612 * Inserts all of the elements in the specified collection into this
613 * list, starting at the specified position. Shifts the element
614 * currently at that position (if any) and any subsequent elements to
615 * the right (increases their indices). The new elements will appear
616 * in the list in the order that they are returned by the
617 * specified collection's iterator.
618 *
619 * @param index index at which to insert the first element from the
620 * specified collection
621 * @param c collection containing elements to be added to this list
622 * @return {@code true} if this list changed as a result of the call
623 * @throws IndexOutOfBoundsException {@inheritDoc}
624 * @throws NullPointerException if the specified collection is null
625 */
626 public boolean addAll(int index, Collection<? extends E> c) {
627 rangeCheckForAdd(index);
628
629 Object[] a = c.toArray();
630 modCount++;
631 int numNew = a.length;
632 if (numNew == 0)
633 return false;
634 Object[] elementData;
635 final int s;
636 if (numNew > (elementData = this.elementData).length - (s = size))
637 elementData = grow(s + numNew);
638
639 int numMoved = s - index;
640 if (numMoved > 0)
641 System.arraycopy(elementData, index,
642 elementData, index + numNew,
643 numMoved);
644 System.arraycopy(a, 0, elementData, index, numNew);
645 size = s + numNew;
646 return true;
647 }
648
649 /**
650 * Removes from this list all of the elements whose index is between
651 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
652 * Shifts any succeeding elements to the left (reduces their index).
653 * This call shortens the list by {@code (toIndex - fromIndex)} elements.
654 * (If {@code toIndex==fromIndex}, this operation has no effect.)
655 *
656 * @throws IndexOutOfBoundsException if {@code fromIndex} or
657 * {@code toIndex} is out of range
658 * ({@code fromIndex < 0 ||
659 * toIndex > size() ||
660 * toIndex < fromIndex})
661 */
662 protected void removeRange(int fromIndex, int toIndex) {
663 if (fromIndex > toIndex) {
664 throw new IndexOutOfBoundsException(
665 outOfBoundsMsg(fromIndex, toIndex));
666 }
667 modCount++;
668 int numMoved = size - toIndex;
669 System.arraycopy(elementData, toIndex, elementData, fromIndex,
670 numMoved);
671
672 // clear to let GC do its work
673 int newSize = size - (toIndex-fromIndex);
674 for (int i = newSize; i < size; i++) {
675 elementData[i] = null;
676 }
677 size = newSize;
678 }
679
680 /**
681 * A version of rangeCheck used by add and addAll.
682 */
683 private void rangeCheckForAdd(int index) {
684 if (index > size || index < 0)
685 throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
686 }
687
688 /**
689 * Constructs an IndexOutOfBoundsException detail message.
690 * Of the many possible refactorings of the error handling code,
691 * this "outlining" performs best with both server and client VMs.
692 */
693 private String outOfBoundsMsg(int index) {
694 return "Index: "+index+", Size: "+size;
695 }
696
697 /**
698 * A version used in checking (fromIndex > toIndex) condition
699 */
700 private static String outOfBoundsMsg(int fromIndex, int toIndex) {
701 return "From Index: " + fromIndex + " > To Index: " + toIndex;
702 }
703
704 /**
705 * Removes from this list all of its elements that are contained in the
706 * specified collection.
707 *
708 * @param c collection containing elements to be removed from this list
709 * @return {@code true} if this list changed as a result of the call
710 * @throws ClassCastException if the class of an element of this list
711 * is incompatible with the specified collection
712 * (<a href="Collection.html#optional-restrictions">optional</a>)
713 * @throws NullPointerException if this list contains a null element and the
714 * specified collection does not permit null elements
715 * (<a href="Collection.html#optional-restrictions">optional</a>),
716 * or if the specified collection is null
717 * @see Collection#contains(Object)
718 */
719 public boolean removeAll(Collection<?> c) {
720 Objects.requireNonNull(c);
721 return batchRemove(c, false);
722 }
723
724 /**
725 * Retains only the elements in this list that are contained in the
726 * specified collection. In other words, removes from this list all
727 * of its elements that are not contained in the specified collection.
728 *
729 * @param c collection containing elements to be retained in this list
730 * @return {@code true} if this list changed as a result of the call
731 * @throws ClassCastException if the class of an element of this list
732 * is incompatible with the specified collection
733 * (<a href="Collection.html#optional-restrictions">optional</a>)
734 * @throws NullPointerException if this list contains a null element and the
735 * specified collection does not permit null elements
736 * (<a href="Collection.html#optional-restrictions">optional</a>),
737 * or if the specified collection is null
738 * @see Collection#contains(Object)
739 */
740 public boolean retainAll(Collection<?> c) {
741 Objects.requireNonNull(c);
742 return batchRemove(c, true);
743 }
744
745 private boolean batchRemove(Collection<?> c, boolean complement) {
746 final Object[] elementData = this.elementData;
747 int r = 0, w = 0;
748 boolean modified = false;
749 try {
750 for (; r < size; r++)
751 if (c.contains(elementData[r]) == complement)
752 elementData[w++] = elementData[r];
753 } finally {
754 // Preserve behavioral compatibility with AbstractCollection,
755 // even if c.contains() throws.
756 if (r != size) {
757 System.arraycopy(elementData, r,
758 elementData, w,
759 size - r);
760 w += size - r;
761 }
762 if (w != size) {
763 // clear to let GC do its work
764 for (int i = w; i < size; i++)
765 elementData[i] = null;
766 modCount += size - w;
767 size = w;
768 modified = true;
769 }
770 }
771 return modified;
772 }
773
774 /**
775 * Save the state of the {@code ArrayList} instance to a stream (that
776 * is, serialize it).
777 *
778 * @serialData The length of the array backing the {@code ArrayList}
779 * instance is emitted (int), followed by all of its elements
780 * (each an {@code Object}) in the proper order.
781 */
782 private void writeObject(java.io.ObjectOutputStream s)
783 throws java.io.IOException{
784 // Write out element count, and any hidden stuff
785 int expectedModCount = modCount;
786 s.defaultWriteObject();
787
788 // Write out size as capacity for behavioural compatibility with clone()
789 s.writeInt(size);
790
791 // Write out all elements in the proper order.
792 for (int i=0; i<size; i++) {
793 s.writeObject(elementData[i]);
794 }
795
796 if (modCount != expectedModCount) {
797 throw new ConcurrentModificationException();
798 }
799 }
800
801 /**
802 * Reconstitute the {@code ArrayList} instance from a stream (that is,
803 * deserialize it).
804 */
805 private void readObject(java.io.ObjectInputStream s)
806 throws java.io.IOException, ClassNotFoundException {
807
808 // Read in size, and any hidden stuff
809 s.defaultReadObject();
810
811 // Read in capacity
812 s.readInt(); // ignored
813
814 if (size > 0) {
815 // like clone(), allocate array based upon size not capacity
816 Object[] elements = new Object[size];
817
818 // Read in all elements in the proper order.
819 for (int i = 0; i < size; i++) {
820 elements[i] = s.readObject();
821 }
822
823 elementData = elements;
824 } else if (size == 0) {
825 elementData = EMPTY_ELEMENTDATA;
826 } else {
827 throw new java.io.InvalidObjectException("Invalid size: " + size);
828 }
829 }
830
831 /**
832 * Returns a list iterator over the elements in this list (in proper
833 * sequence), starting at the specified position in the list.
834 * The specified index indicates the first element that would be
835 * returned by an initial call to {@link ListIterator#next next}.
836 * An initial call to {@link ListIterator#previous previous} would
837 * return the element with the specified index minus one.
838 *
839 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
840 *
841 * @throws IndexOutOfBoundsException {@inheritDoc}
842 */
843 public ListIterator<E> listIterator(int index) {
844 rangeCheckForAdd(index);
845 return new ListItr(index);
846 }
847
848 /**
849 * Returns a list iterator over the elements in this list (in proper
850 * sequence).
851 *
852 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
853 *
854 * @see #listIterator(int)
855 */
856 public ListIterator<E> listIterator() {
857 return new ListItr(0);
858 }
859
860 /**
861 * Returns an iterator over the elements in this list in proper sequence.
862 *
863 * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
864 *
865 * @return an iterator over the elements in this list in proper sequence
866 */
867 public Iterator<E> iterator() {
868 return new Itr();
869 }
870
871 /**
872 * An optimized version of AbstractList.Itr
873 */
874 private class Itr implements Iterator<E> {
875 int cursor; // index of next element to return
876 int lastRet = -1; // index of last element returned; -1 if no such
877 int expectedModCount = modCount;
878
879 Itr() {}
880
881 public boolean hasNext() {
882 return cursor != size;
883 }
884
885 @SuppressWarnings("unchecked")
886 public E next() {
887 checkForComodification();
888 int i = cursor;
889 if (i >= size)
890 throw new NoSuchElementException();
891 Object[] elementData = ArrayList.this.elementData;
892 if (i >= elementData.length)
893 throw new ConcurrentModificationException();
894 cursor = i + 1;
895 return (E) elementData[lastRet = i];
896 }
897
898 public void remove() {
899 if (lastRet < 0)
900 throw new IllegalStateException();
901 checkForComodification();
902
903 try {
904 ArrayList.this.remove(lastRet);
905 cursor = lastRet;
906 lastRet = -1;
907 expectedModCount = modCount;
908 } catch (IndexOutOfBoundsException ex) {
909 throw new ConcurrentModificationException();
910 }
911 }
912
913 @Override
914 @SuppressWarnings("unchecked")
915 public void forEachRemaining(Consumer<? super E> consumer) {
916 Objects.requireNonNull(consumer);
917 final int size = ArrayList.this.size;
918 int i = cursor;
919 if (i >= size) {
920 return;
921 }
922 final Object[] elementData = ArrayList.this.elementData;
923 if (i >= elementData.length) {
924 throw new ConcurrentModificationException();
925 }
926 while (i != size && modCount == expectedModCount) {
927 consumer.accept((E) elementData[i++]);
928 }
929 // update once at end of iteration to reduce heap write traffic
930 cursor = i;
931 lastRet = i - 1;
932 checkForComodification();
933 }
934
935 final void checkForComodification() {
936 if (modCount != expectedModCount)
937 throw new ConcurrentModificationException();
938 }
939 }
940
941 /**
942 * An optimized version of AbstractList.ListItr
943 */
944 private class ListItr extends Itr implements ListIterator<E> {
945 ListItr(int index) {
946 super();
947 cursor = index;
948 }
949
950 public boolean hasPrevious() {
951 return cursor != 0;
952 }
953
954 public int nextIndex() {
955 return cursor;
956 }
957
958 public int previousIndex() {
959 return cursor - 1;
960 }
961
962 @SuppressWarnings("unchecked")
963 public E previous() {
964 checkForComodification();
965 int i = cursor - 1;
966 if (i < 0)
967 throw new NoSuchElementException();
968 Object[] elementData = ArrayList.this.elementData;
969 if (i >= elementData.length)
970 throw new ConcurrentModificationException();
971 cursor = i;
972 return (E) elementData[lastRet = i];
973 }
974
975 public void set(E e) {
976 if (lastRet < 0)
977 throw new IllegalStateException();
978 checkForComodification();
979
980 try {
981 ArrayList.this.set(lastRet, e);
982 } catch (IndexOutOfBoundsException ex) {
983 throw new ConcurrentModificationException();
984 }
985 }
986
987 public void add(E e) {
988 checkForComodification();
989
990 try {
991 int i = cursor;
992 ArrayList.this.add(i, e);
993 cursor = i + 1;
994 lastRet = -1;
995 expectedModCount = modCount;
996 } catch (IndexOutOfBoundsException ex) {
997 throw new ConcurrentModificationException();
998 }
999 }
1000 }
1001
1002 /**
1003 * Returns a view of the portion of this list between the specified
1004 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. (If
1005 * {@code fromIndex} and {@code toIndex} are equal, the returned list is
1006 * empty.) The returned list is backed by this list, so non-structural
1007 * changes in the returned list are reflected in this list, and vice-versa.
1008 * The returned list supports all of the optional list operations.
1009 *
1010 * <p>This method eliminates the need for explicit range operations (of
1011 * the sort that commonly exist for arrays). Any operation that expects
1012 * a list can be used as a range operation by passing a subList view
1013 * instead of a whole list. For example, the following idiom
1014 * removes a range of elements from a list:
1015 * <pre>
1016 * list.subList(from, to).clear();
1017 * </pre>
1018 * Similar idioms may be constructed for {@link #indexOf(Object)} and
1019 * {@link #lastIndexOf(Object)}, and all of the algorithms in the
1020 * {@link Collections} class can be applied to a subList.
1021 *
1022 * <p>The semantics of the list returned by this method become undefined if
1023 * the backing list (i.e., this list) is <i>structurally modified</i> in
1024 * any way other than via the returned list. (Structural modifications are
1025 * those that change the size of this list, or otherwise perturb it in such
1026 * a fashion that iterations in progress may yield incorrect results.)
1027 *
1028 * @throws IndexOutOfBoundsException {@inheritDoc}
1029 * @throws IllegalArgumentException {@inheritDoc}
1030 */
1031 public List<E> subList(int fromIndex, int toIndex) {
1032 subListRangeCheck(fromIndex, toIndex, size);
1033 return new SubList<>(this, fromIndex, toIndex);
1034 }
1035
1036 private static class SubList<E> extends AbstractList<E> implements RandomAccess {
1037 private final ArrayList<E> root;
1038 private final SubList<E> parent;
1039 private final int offset;
1040 private int size;
1041
1042 /**
1043 * Constructs a sublist of an arbitrary ArrayList.
1044 */
1045 public SubList(ArrayList<E> root, int fromIndex, int toIndex) {
1046 this.root = root;
1047 this.parent = null;
1048 this.offset = fromIndex;
1049 this.size = toIndex - fromIndex;
1050 this.modCount = root.modCount;
1051 }
1052
1053 /**
1054 * Constructs a sublist of another SubList.
1055 */
1056 private SubList(SubList<E> parent, int fromIndex, int toIndex) {
1057 this.root = parent.root;
1058 this.parent = parent;
1059 this.offset = parent.offset + fromIndex;
1060 this.size = toIndex - fromIndex;
1061 this.modCount = root.modCount;
1062 }
1063
1064 public E set(int index, E element) {
1065 Objects.checkIndex(index, size);
1066 checkForComodification();
1067 E oldValue = root.elementData(offset + index);
1068 root.elementData[offset + index] = element;
1069 return oldValue;
1070 }
1071
1072 public E get(int index) {
1073 Objects.checkIndex(index, size);
1074 checkForComodification();
1075 return root.elementData(offset + index);
1076 }
1077
1078 public int size() {
1079 checkForComodification();
1080 return size;
1081 }
1082
1083 public void add(int index, E element) {
1084 rangeCheckForAdd(index);
1085 checkForComodification();
1086 root.add(offset + index, element);
1087 updateSizeAndModCount(1);
1088 }
1089
1090 public E remove(int index) {
1091 Objects.checkIndex(index, size);
1092 checkForComodification();
1093 E result = root.remove(offset + index);
1094 updateSizeAndModCount(-1);
1095 return result;
1096 }
1097
1098 protected void removeRange(int fromIndex, int toIndex) {
1099 checkForComodification();
1100 root.removeRange(offset + fromIndex, offset + toIndex);
1101 updateSizeAndModCount(fromIndex - toIndex);
1102 }
1103
1104 public boolean addAll(Collection<? extends E> c) {
1105 return addAll(this.size, c);
1106 }
1107
1108 public boolean addAll(int index, Collection<? extends E> c) {
1109 rangeCheckForAdd(index);
1110 int cSize = c.size();
1111 if (cSize==0)
1112 return false;
1113 checkForComodification();
1114 root.addAll(offset + index, c);
1115 updateSizeAndModCount(cSize);
1116 return true;
1117 }
1118
1119 public Iterator<E> iterator() {
1120 return listIterator();
1121 }
1122
1123 public ListIterator<E> listIterator(int index) {
1124 checkForComodification();
1125 rangeCheckForAdd(index);
1126
1127 return new ListIterator<E>() {
1128 int cursor = index;
1129 int lastRet = -1;
1130 int expectedModCount = root.modCount;
1131
1132 public boolean hasNext() {
1133 return cursor != SubList.this.size;
1134 }
1135
1136 @SuppressWarnings("unchecked")
1137 public E next() {
1138 checkForComodification();
1139 int i = cursor;
1140 if (i >= SubList.this.size)
1141 throw new NoSuchElementException();
1142 Object[] elementData = root.elementData;
1143 if (offset + i >= elementData.length)
1144 throw new ConcurrentModificationException();
1145 cursor = i + 1;
1146 return (E) elementData[offset + (lastRet = i)];
1147 }
1148
1149 public boolean hasPrevious() {
1150 return cursor != 0;
1151 }
1152
1153 @SuppressWarnings("unchecked")
1154 public E previous() {
1155 checkForComodification();
1156 int i = cursor - 1;
1157 if (i < 0)
1158 throw new NoSuchElementException();
1159 Object[] elementData = root.elementData;
1160 if (offset + i >= elementData.length)
1161 throw new ConcurrentModificationException();
1162 cursor = i;
1163 return (E) elementData[offset + (lastRet = i)];
1164 }
1165
1166 @SuppressWarnings("unchecked")
1167 public void forEachRemaining(Consumer<? super E> consumer) {
1168 Objects.requireNonNull(consumer);
1169 final int size = SubList.this.size;
1170 int i = cursor;
1171 if (i >= size) {
1172 return;
1173 }
1174 final Object[] elementData = root.elementData;
1175 if (offset + i >= elementData.length) {
1176 throw new ConcurrentModificationException();
1177 }
1178 while (i != size && modCount == expectedModCount) {
1179 consumer.accept((E) elementData[offset + (i++)]);
1180 }
1181 // update once at end of iteration to reduce heap write traffic
1182 lastRet = cursor = i;
1183 checkForComodification();
1184 }
1185
1186 public int nextIndex() {
1187 return cursor;
1188 }
1189
1190 public int previousIndex() {
1191 return cursor - 1;
1192 }
1193
1194 public void remove() {
1195 if (lastRet < 0)
1196 throw new IllegalStateException();
1197 checkForComodification();
1198
1199 try {
1200 SubList.this.remove(lastRet);
1201 cursor = lastRet;
1202 lastRet = -1;
1203 expectedModCount = root.modCount;
1204 } catch (IndexOutOfBoundsException ex) {
1205 throw new ConcurrentModificationException();
1206 }
1207 }
1208
1209 public void set(E e) {
1210 if (lastRet < 0)
1211 throw new IllegalStateException();
1212 checkForComodification();
1213
1214 try {
1215 root.set(offset + lastRet, e);
1216 } catch (IndexOutOfBoundsException ex) {
1217 throw new ConcurrentModificationException();
1218 }
1219 }
1220
1221 public void add(E e) {
1222 checkForComodification();
1223
1224 try {
1225 int i = cursor;
1226 SubList.this.add(i, e);
1227 cursor = i + 1;
1228 lastRet = -1;
1229 expectedModCount = root.modCount;
1230 } catch (IndexOutOfBoundsException ex) {
1231 throw new ConcurrentModificationException();
1232 }
1233 }
1234
1235 final void checkForComodification() {
1236 if (root.modCount != expectedModCount)
1237 throw new ConcurrentModificationException();
1238 }
1239 };
1240 }
1241
1242 public List<E> subList(int fromIndex, int toIndex) {
1243 subListRangeCheck(fromIndex, toIndex, size);
1244 return new SubList<>(this, fromIndex, toIndex);
1245 }
1246
1247 private void rangeCheckForAdd(int index) {
1248 if (index < 0 || index > this.size)
1249 throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1250 }
1251
1252 private String outOfBoundsMsg(int index) {
1253 return "Index: "+index+", Size: "+this.size;
1254 }
1255
1256 private void checkForComodification() {
1257 if (root.modCount != modCount)
1258 throw new ConcurrentModificationException();
1259 }
1260
1261 private void updateSizeAndModCount(int sizeChange) {
1262 SubList<E> slist = this;
1263 do {
1264 slist.size += sizeChange;
1265 slist.modCount = root.modCount;
1266 slist = slist.parent;
1267 } while (slist != null);
1268 }
1269
1270 public Spliterator<E> spliterator() {
1271 checkForComodification();
1272
1273 // ArrayListSpliterator is not used because late-binding logic
1274 // is different here
1275 return new Spliterator<>() {
1276 private int index = offset; // current index, modified on advance/split
1277 private int fence = -1; // -1 until used; then one past last index
1278 private int expectedModCount; // initialized when fence set
1279
1280 private int getFence() { // initialize fence to size on first use
1281 int hi; // (a specialized variant appears in method forEach)
1282 if ((hi = fence) < 0) {
1283 expectedModCount = modCount;
1284 hi = fence = offset + size;
1285 }
1286 return hi;
1287 }
1288
1289 public ArrayListSpliterator<E> trySplit() {
1290 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1291 // ArrayListSpliterator could be used here as the source is already bound
1292 return (lo >= mid) ? null : // divide range in half unless too small
1293 new ArrayListSpliterator<>(root, lo, index = mid,
1294 expectedModCount);
1295 }
1296
1297 public boolean tryAdvance(Consumer<? super E> action) {
1298 Objects.requireNonNull(action);
1299 int hi = getFence(), i = index;
1300 if (i < hi) {
1301 index = i + 1;
1302 @SuppressWarnings("unchecked") E e = (E)root.elementData[i];
1303 action.accept(e);
1304 if (root.modCount != expectedModCount)
1305 throw new ConcurrentModificationException();
1306 return true;
1307 }
1308 return false;
1309 }
1310
1311 public void forEachRemaining(Consumer<? super E> action) {
1312 Objects.requireNonNull(action);
1313 int i, hi, mc; // hoist accesses and checks from loop
1314 ArrayList<E> lst = root;
1315 Object[] a;
1316 if ((a = lst.elementData) != null) {
1317 if ((hi = fence) < 0) {
1318 mc = modCount;
1319 hi = offset + size;
1320 }
1321 else
1322 mc = expectedModCount;
1323 if ((i = index) >= 0 && (index = hi) <= a.length) {
1324 for (; i < hi; ++i) {
1325 @SuppressWarnings("unchecked") E e = (E) a[i];
1326 action.accept(e);
1327 }
1328 if (lst.modCount == mc)
1329 return;
1330 }
1331 }
1332 throw new ConcurrentModificationException();
1333 }
1334
1335 public long estimateSize() {
1336 return (long) (getFence() - index);
1337 }
1338
1339 public int characteristics() {
1340 return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
1341 }
1342 };
1343 }
1344 }
1345
1346 @Override
1347 public void forEach(Consumer<? super E> action) {
1348 Objects.requireNonNull(action);
1349 final int expectedModCount = modCount;
1350 @SuppressWarnings("unchecked")
1351 final E[] elementData = (E[]) this.elementData;
1352 final int size = this.size;
1353 for (int i=0; modCount == expectedModCount && i < size; i++) {
1354 action.accept(elementData[i]);
1355 }
1356 if (modCount != expectedModCount) {
1357 throw new ConcurrentModificationException();
1358 }
1359 }
1360
1361 /**
1362 * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
1363 * and <em>fail-fast</em> {@link Spliterator} over the elements in this
1364 * list.
1365 *
1366 * <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
1367 * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}.
1368 * Overriding implementations should document the reporting of additional
1369 * characteristic values.
1370 *
1371 * @return a {@code Spliterator} over the elements in this list
1372 * @since 1.8
1373 */
1374 @Override
1375 public Spliterator<E> spliterator() {
1376 return new ArrayListSpliterator<>(this, 0, -1, 0);
1377 }
1378
1379 /** Index-based split-by-two, lazily initialized Spliterator */
1380 static final class ArrayListSpliterator<E> implements Spliterator<E> {
1381
1382 /*
1383 * If ArrayLists were immutable, or structurally immutable (no
1384 * adds, removes, etc), we could implement their spliterators
1385 * with Arrays.spliterator. Instead we detect as much
1386 * interference during traversal as practical without
1387 * sacrificing much performance. We rely primarily on
1388 * modCounts. These are not guaranteed to detect concurrency
1389 * violations, and are sometimes overly conservative about
1390 * within-thread interference, but detect enough problems to
1391 * be worthwhile in practice. To carry this out, we (1) lazily
1392 * initialize fence and expectedModCount until the latest
1393 * point that we need to commit to the state we are checking
1394 * against; thus improving precision. (This doesn't apply to
1395 * SubLists, that create spliterators with current non-lazy
1396 * values). (2) We perform only a single
1397 * ConcurrentModificationException check at the end of forEach
1398 * (the most performance-sensitive method). When using forEach
1399 * (as opposed to iterators), we can normally only detect
1400 * interference after actions, not before. Further
1401 * CME-triggering checks apply to all other possible
1402 * violations of assumptions for example null or too-small
1403 * elementData array given its size(), that could only have
1404 * occurred due to interference. This allows the inner loop
1405 * of forEach to run without any further checks, and
1406 * simplifies lambda-resolution. While this does entail a
1407 * number of checks, note that in the common case of
1408 * list.stream().forEach(a), no checks or other computation
1409 * occur anywhere other than inside forEach itself. The other
1410 * less-often-used methods cannot take advantage of most of
1411 * these streamlinings.
1412 */
1413
1414 private final ArrayList<E> list;
1415 private int index; // current index, modified on advance/split
1416 private int fence; // -1 until used; then one past last index
1417 private int expectedModCount; // initialized when fence set
1418
1419 /** Create new spliterator covering the given range */
1420 ArrayListSpliterator(ArrayList<E> list, int origin, int fence,
1421 int expectedModCount) {
1422 this.list = list; // OK if null unless traversed
1423 this.index = origin;
1424 this.fence = fence;
1425 this.expectedModCount = expectedModCount;
1426 }
1427
1428 private int getFence() { // initialize fence to size on first use
1429 int hi; // (a specialized variant appears in method forEach)
1430 ArrayList<E> lst;
1431 if ((hi = fence) < 0) {
1432 if ((lst = list) == null)
1433 hi = fence = 0;
1434 else {
1435 expectedModCount = lst.modCount;
1436 hi = fence = lst.size;
1437 }
1438 }
1439 return hi;
1440 }
1441
1442 public ArrayListSpliterator<E> trySplit() {
1443 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1444 return (lo >= mid) ? null : // divide range in half unless too small
1445 new ArrayListSpliterator<>(list, lo, index = mid,
1446 expectedModCount);
1447 }
1448
1449 public boolean tryAdvance(Consumer<? super E> action) {
1450 if (action == null)
1451 throw new NullPointerException();
1452 int hi = getFence(), i = index;
1453 if (i < hi) {
1454 index = i + 1;
1455 @SuppressWarnings("unchecked") E e = (E)list.elementData[i];
1456 action.accept(e);
1457 if (list.modCount != expectedModCount)
1458 throw new ConcurrentModificationException();
1459 return true;
1460 }
1461 return false;
1462 }
1463
1464 public void forEachRemaining(Consumer<? super E> action) {
1465 int i, hi, mc; // hoist accesses and checks from loop
1466 ArrayList<E> lst; Object[] a;
1467 if (action == null)
1468 throw new NullPointerException();
1469 if ((lst = list) != null && (a = lst.elementData) != null) {
1470 if ((hi = fence) < 0) {
1471 mc = lst.modCount;
1472 hi = lst.size;
1473 }
1474 else
1475 mc = expectedModCount;
1476 if ((i = index) >= 0 && (index = hi) <= a.length) {
1477 for (; i < hi; ++i) {
1478 @SuppressWarnings("unchecked") E e = (E) a[i];
1479 action.accept(e);
1480 }
1481 if (lst.modCount == mc)
1482 return;
1483 }
1484 }
1485 throw new ConcurrentModificationException();
1486 }
1487
1488 public long estimateSize() {
1489 return (long) (getFence() - index);
1490 }
1491
1492 public int characteristics() {
1493 return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
1494 }
1495 }
1496
1497 @Override
1498 public boolean removeIf(Predicate<? super E> filter) {
1499 Objects.requireNonNull(filter);
1500 // figure out which elements are to be removed
1501 // any exception thrown from the filter predicate at this stage
1502 // will leave the collection unmodified
1503 int removeCount = 0;
1504 final BitSet removeSet = new BitSet(size);
1505 final int expectedModCount = modCount;
1506 final int size = this.size;
1507 for (int i=0; modCount == expectedModCount && i < size; i++) {
1508 @SuppressWarnings("unchecked")
1509 final E element = (E) elementData[i];
1510 if (filter.test(element)) {
1511 removeSet.set(i);
1512 removeCount++;
1513 }
1514 }
1515 if (modCount != expectedModCount) {
1516 throw new ConcurrentModificationException();
1517 }
1518
1519 // shift surviving elements left over the spaces left by removed elements
1520 final boolean anyToRemove = removeCount > 0;
1521 if (anyToRemove) {
1522 final int newSize = size - removeCount;
1523 for (int i=0, j=0; (i < size) && (j < newSize); i++, j++) {
1524 i = removeSet.nextClearBit(i);
1525 elementData[j] = elementData[i];
1526 }
1527 for (int k=newSize; k < size; k++) {
1528 elementData[k] = null; // Let gc do its work
1529 }
1530 this.size = newSize;
1531 if (modCount != expectedModCount) {
1532 throw new ConcurrentModificationException();
1533 }
1534 modCount++;
1535 }
1536
1537 return anyToRemove;
1538 }
1539
1540 @Override
1541 @SuppressWarnings("unchecked")
1542 public void replaceAll(UnaryOperator<E> operator) {
1543 Objects.requireNonNull(operator);
1544 final int expectedModCount = modCount;
1545 final int size = this.size;
1546 for (int i=0; modCount == expectedModCount && i < size; i++) {
1547 elementData[i] = operator.apply((E) elementData[i]);
1548 }
1549 if (modCount != expectedModCount) {
1550 throw new ConcurrentModificationException();
1551 }
1552 modCount++;
1553 }
1554
1555 @Override
1556 @SuppressWarnings("unchecked")
1557 public void sort(Comparator<? super E> c) {
1558 final int expectedModCount = modCount;
1559 Arrays.sort((E[]) elementData, 0, size, c);
1560 if (modCount != expectedModCount) {
1561 throw new ConcurrentModificationException();
1562 }
1563 modCount++;
1564 }
1565 }