1 /* 2 * Copyright (c) 1997, 2017, 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 import jdk.internal.misc.SharedSecrets; 32 33 /** 34 * Resizable-array implementation of the {@code List} interface. Implements 35 * all optional list operations, and permits all elements, including 36 * {@code null}. In addition to implementing the {@code List} interface, 37 * this class provides methods to manipulate the size of the array that is 38 * used internally to store the list. (This class is roughly equivalent to 39 * {@code Vector}, except that it is unsynchronized.) 40 * 41 * <p>The {@code size}, {@code isEmpty}, {@code get}, {@code set}, 42 * {@code iterator}, and {@code listIterator} operations run in constant 43 * time. The {@code add} operation runs in <i>amortized constant time</i>, 44 * that is, adding n elements requires O(n) time. All of the other operations 45 * run in linear time (roughly speaking). The constant factor is low compared 46 * to that for the {@code LinkedList} implementation. 47 * 48 * <p>Each {@code ArrayList} instance has a <i>capacity</i>. The capacity is 49 * the size of the array used to store the elements in the list. It is always 50 * at least as large as the list size. As elements are added to an ArrayList, 51 * its capacity grows automatically. The details of the growth policy are not 52 * specified beyond the fact that adding an element has constant amortized 53 * time cost. 54 * 55 * <p>An application can increase the capacity of an {@code ArrayList} instance 56 * before adding a large number of elements using the {@code ensureCapacity} 57 * operation. This may reduce the amount of incremental reallocation. 58 * 59 * <p><strong>Note that this implementation is not synchronized.</strong> 60 * If multiple threads access an {@code ArrayList} instance concurrently, 61 * and at least one of the threads modifies the list structurally, it 62 * <i>must</i> be synchronized externally. (A structural modification is 63 * any operation that adds or deletes one or more elements, or explicitly 64 * resizes the backing array; merely setting the value of an element is not 65 * a structural modification.) This is typically accomplished by 66 * synchronizing on some object that naturally encapsulates the list. 67 * 68 * If no such object exists, the list should be "wrapped" using the 69 * {@link Collections#synchronizedList Collections.synchronizedList} 70 * method. This is best done at creation time, to prevent accidental 71 * unsynchronized access to the list:<pre> 72 * List list = Collections.synchronizedList(new ArrayList(...));</pre> 73 * 74 * <p id="fail-fast"> 75 * The iterators returned by this class's {@link #iterator() iterator} and 76 * {@link #listIterator(int) listIterator} methods are <em>fail-fast</em>: 77 * if the list is structurally modified at any time after the iterator is 78 * created, in any way except through the iterator's own 79 * {@link ListIterator#remove() remove} or 80 * {@link ListIterator#add(Object) add} methods, the iterator will throw a 81 * {@link ConcurrentModificationException}. Thus, in the face of 82 * concurrent modification, the iterator fails quickly and cleanly, rather 83 * than risking arbitrary, non-deterministic behavior at an undetermined 84 * time in the future. 85 * 86 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed 87 * as it is, generally speaking, impossible to make any hard guarantees in the 88 * presence of unsynchronized concurrent modification. Fail-fast iterators 89 * throw {@code ConcurrentModificationException} on a best-effort basis. 90 * Therefore, it would be wrong to write a program that depended on this 91 * exception for its correctness: <i>the fail-fast behavior of iterators 92 * should be used only to detect bugs.</i> 93 * 94 * <p>This class is a member of the 95 * <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework"> 96 * Java Collections Framework</a>. 97 * 98 * @param <E> the type of elements in this list 99 * 100 * @author Josh Bloch 101 * @author Neal Gafter 102 * @see Collection 103 * @see List 104 * @see LinkedList 105 * @see Vector 106 * @since 1.2 107 */ 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 @SuppressWarnings("unchecked") 428 static <E> E elementAt(Object[] es, int index) { 429 return (E) es[index]; 430 } 431 432 /** 433 * Returns the element at the specified position in this list. 434 * 435 * @param index index of the element to return 436 * @return the element at the specified position in this list 437 * @throws IndexOutOfBoundsException {@inheritDoc} 438 */ 439 public E get(int index) { 440 Objects.checkIndex(index, size); 441 return elementData(index); 442 } 443 444 /** 445 * Replaces the element at the specified position in this list with 446 * the specified element. 447 * 448 * @param index index of the element to replace 449 * @param element element to be stored at the specified position 450 * @return the element previously at the specified position 451 * @throws IndexOutOfBoundsException {@inheritDoc} 452 */ 453 public E set(int index, E element) { 454 Objects.checkIndex(index, size); 455 E oldValue = elementData(index); 456 elementData[index] = element; 457 return oldValue; 458 } 459 460 /** 461 * This helper method split out from add(E) to keep method 462 * bytecode size under 35 (the -XX:MaxInlineSize default value), 463 * which helps when add(E) is called in a C1-compiled loop. 464 */ 465 private void add(E e, Object[] elementData, int s) { 466 if (s == elementData.length) 467 elementData = grow(); 468 elementData[s] = e; 469 size = s + 1; 470 } 471 472 /** 473 * Appends the specified element to the end of this list. 474 * 475 * @param e element to be appended to this list 476 * @return {@code true} (as specified by {@link Collection#add}) 477 */ 478 public boolean add(E e) { 479 modCount++; 480 add(e, elementData, size); 481 return true; 482 } 483 484 /** 485 * Inserts the specified element at the specified position in this 486 * list. Shifts the element currently at that position (if any) and 487 * any subsequent elements to the right (adds one to their indices). 488 * 489 * @param index index at which the specified element is to be inserted 490 * @param element element to be inserted 491 * @throws IndexOutOfBoundsException {@inheritDoc} 492 */ 493 public void add(int index, E element) { 494 rangeCheckForAdd(index); 495 modCount++; 496 final int s; 497 Object[] elementData; 498 if ((s = size) == (elementData = this.elementData).length) 499 elementData = grow(); 500 System.arraycopy(elementData, index, 501 elementData, index + 1, 502 s - index); 503 elementData[index] = element; 504 size = s + 1; 505 } 506 507 /** 508 * Removes the element at the specified position in this list. 509 * Shifts any subsequent elements to the left (subtracts one from their 510 * indices). 511 * 512 * @param index the index of the element to be removed 513 * @return the element that was removed from the list 514 * @throws IndexOutOfBoundsException {@inheritDoc} 515 */ 516 public E remove(int index) { 517 Objects.checkIndex(index, size); 518 final Object[] es = elementData; 519 520 @SuppressWarnings("unchecked") E oldValue = (E) es[index]; 521 fastRemove(es, index); 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 final Object[] es = elementData; 541 final int size = this.size; 542 int i = 0; 543 found: { 544 if (o == null) { 545 for (; i < size; i++) 546 if (es[i] == null) 547 break found; 548 } else { 549 for (; i < size; i++) 550 if (o.equals(es[i])) 551 break found; 552 } 553 return false; 554 } 555 fastRemove(es, i); 556 return true; 557 } 558 559 /** 560 * Private remove method that skips bounds checking and does not 561 * return the value removed. 562 */ 563 private void fastRemove(Object[] es, int i) { 564 modCount++; 565 final int newSize; 566 if ((newSize = size - 1) > i) 567 System.arraycopy(es, i + 1, es, i, newSize - i); 568 es[size = newSize] = null; 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 final Object[] es = elementData; 578 for (int to = size, i = size = 0; i < to; i++) 579 es[i] = null; 580 } 581 582 /** 583 * Appends all of the elements in the specified collection to the end of 584 * this list, in the order that they are returned by the 585 * specified collection's Iterator. The behavior of this operation is 586 * undefined if the specified collection is modified while the operation 587 * is in progress. (This implies that the behavior of this call is 588 * undefined if the specified collection is this list, and this 589 * list is nonempty.) 590 * 591 * @param c collection containing elements to be added to this list 592 * @return {@code true} if this list changed as a result of the call 593 * @throws NullPointerException if the specified collection is null 594 */ 595 public boolean addAll(Collection<? extends E> c) { 596 Object[] a = c.toArray(); 597 modCount++; 598 int numNew = a.length; 599 if (numNew == 0) 600 return false; 601 Object[] elementData; 602 final int s; 603 if (numNew > (elementData = this.elementData).length - (s = size)) 604 elementData = grow(s + numNew); 605 System.arraycopy(a, 0, elementData, s, numNew); 606 size = s + numNew; 607 return true; 608 } 609 610 /** 611 * Inserts all of the elements in the specified collection into this 612 * list, starting at the specified position. Shifts the element 613 * currently at that position (if any) and any subsequent elements to 614 * the right (increases their indices). The new elements will appear 615 * in the list in the order that they are returned by the 616 * specified collection's iterator. 617 * 618 * @param index index at which to insert the first element from the 619 * specified collection 620 * @param c collection containing elements to be added to this list 621 * @return {@code true} if this list changed as a result of the call 622 * @throws IndexOutOfBoundsException {@inheritDoc} 623 * @throws NullPointerException if the specified collection is null 624 */ 625 public boolean addAll(int index, Collection<? extends E> c) { 626 rangeCheckForAdd(index); 627 628 Object[] a = c.toArray(); 629 modCount++; 630 int numNew = a.length; 631 if (numNew == 0) 632 return false; 633 Object[] elementData; 634 final int s; 635 if (numNew > (elementData = this.elementData).length - (s = size)) 636 elementData = grow(s + numNew); 637 638 int numMoved = s - index; 639 if (numMoved > 0) 640 System.arraycopy(elementData, index, 641 elementData, index + numNew, 642 numMoved); 643 System.arraycopy(a, 0, elementData, index, numNew); 644 size = s + numNew; 645 return true; 646 } 647 648 /** 649 * Removes from this list all of the elements whose index is between 650 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. 651 * Shifts any succeeding elements to the left (reduces their index). 652 * This call shortens the list by {@code (toIndex - fromIndex)} elements. 653 * (If {@code toIndex==fromIndex}, this operation has no effect.) 654 * 655 * @throws IndexOutOfBoundsException if {@code fromIndex} or 656 * {@code toIndex} is out of range 657 * ({@code fromIndex < 0 || 658 * toIndex > size() || 659 * toIndex < fromIndex}) 660 */ 661 protected void removeRange(int fromIndex, int toIndex) { 662 if (fromIndex > toIndex) { 663 throw new IndexOutOfBoundsException( 664 outOfBoundsMsg(fromIndex, toIndex)); 665 } 666 modCount++; 667 shiftTailOverGap(elementData, fromIndex, toIndex); 668 } 669 670 /** Erases the gap from lo to hi, by sliding down following elements. */ 671 private void shiftTailOverGap(Object[] es, int lo, int hi) { 672 System.arraycopy(es, hi, es, lo, size - hi); 673 for (int to = size, i = (size -= hi - lo); i < to; i++) 674 es[i] = null; 675 } 676 677 /** 678 * A version of rangeCheck used by add and addAll. 679 */ 680 private void rangeCheckForAdd(int index) { 681 if (index > size || index < 0) 682 throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); 683 } 684 685 /** 686 * Constructs an IndexOutOfBoundsException detail message. 687 * Of the many possible refactorings of the error handling code, 688 * this "outlining" performs best with both server and client VMs. 689 */ 690 private String outOfBoundsMsg(int index) { 691 return "Index: "+index+", Size: "+size; 692 } 693 694 /** 695 * A version used in checking (fromIndex > toIndex) condition 696 */ 697 private static String outOfBoundsMsg(int fromIndex, int toIndex) { 698 return "From Index: " + fromIndex + " > To Index: " + toIndex; 699 } 700 701 /** 702 * Removes from this list all of its elements that are contained in the 703 * specified collection. 704 * 705 * @param c collection containing elements to be removed from this list 706 * @return {@code true} if this list changed as a result of the call 707 * @throws ClassCastException if the class of an element of this list 708 * is incompatible with the specified collection 709 * (<a href="Collection.html#optional-restrictions">optional</a>) 710 * @throws NullPointerException if this list contains a null element and the 711 * specified collection does not permit null elements 712 * (<a href="Collection.html#optional-restrictions">optional</a>), 713 * or if the specified collection is null 714 * @see Collection#contains(Object) 715 */ 716 public boolean removeAll(Collection<?> c) { 717 return batchRemove(c, false, 0, size); 718 } 719 720 /** 721 * Retains only the elements in this list that are contained in the 722 * specified collection. In other words, removes from this list all 723 * of its elements that are not contained in the specified collection. 724 * 725 * @param c collection containing elements to be retained in this list 726 * @return {@code true} if this list changed as a result of the call 727 * @throws ClassCastException if the class of an element of this list 728 * is incompatible with the specified collection 729 * (<a href="Collection.html#optional-restrictions">optional</a>) 730 * @throws NullPointerException if this list contains a null element and the 731 * specified collection does not permit null elements 732 * (<a href="Collection.html#optional-restrictions">optional</a>), 733 * or if the specified collection is null 734 * @see Collection#contains(Object) 735 */ 736 public boolean retainAll(Collection<?> c) { 737 return batchRemove(c, true, 0, size); 738 } 739 740 boolean batchRemove(Collection<?> c, boolean complement, 741 final int from, final int end) { 742 Objects.requireNonNull(c); 743 final Object[] es = elementData; 744 int r; 745 // Optimize for initial run of survivors 746 for (r = from;; r++) { 747 if (r == end) 748 return false; 749 if (c.contains(es[r]) != complement) 750 break; 751 } 752 int w = r++; 753 try { 754 for (Object e; r < end; r++) 755 if (c.contains(e = es[r]) == complement) 756 es[w++] = e; 757 } catch (Throwable ex) { 758 // Preserve behavioral compatibility with AbstractCollection, 759 // even if c.contains() throws. 760 System.arraycopy(es, r, es, w, end - r); 761 w += end - r; 762 throw ex; 763 } finally { 764 modCount += end - w; 765 shiftTailOverGap(es, w, end); 766 } 767 return true; 768 } 769 770 /** 771 * Saves the state of the {@code ArrayList} instance to a stream 772 * (that is, serializes it). 773 * 774 * @param s the stream 775 * @throws java.io.IOException if an I/O error occurs 776 * @serialData The length of the array backing the {@code ArrayList} 777 * instance is emitted (int), followed by all of its elements 778 * (each an {@code Object}) in the proper order. 779 */ 780 private void writeObject(java.io.ObjectOutputStream s) 781 throws java.io.IOException { 782 // Write out element count, and any hidden stuff 783 int expectedModCount = modCount; 784 s.defaultWriteObject(); 785 786 // Write out size as capacity for behavioral compatibility with clone() 787 s.writeInt(size); 788 789 // Write out all elements in the proper order. 790 for (int i=0; i<size; i++) { 791 s.writeObject(elementData[i]); 792 } 793 794 if (modCount != expectedModCount) { 795 throw new ConcurrentModificationException(); 796 } 797 } 798 799 /** 800 * Reconstitutes the {@code ArrayList} instance from a stream (that is, 801 * deserializes it). 802 * @param s the stream 803 * @throws ClassNotFoundException if the class of a serialized object 804 * could not be found 805 * @throws java.io.IOException if an I/O error occurs 806 */ 807 private void readObject(java.io.ObjectInputStream s) 808 throws java.io.IOException, ClassNotFoundException { 809 810 // Read in size, and any hidden stuff 811 s.defaultReadObject(); 812 813 // Read in capacity 814 s.readInt(); // ignored 815 816 if (size > 0) { 817 // like clone(), allocate array based upon size not capacity 818 SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size); 819 Object[] elements = new Object[size]; 820 821 // Read in all elements in the proper order. 822 for (int i = 0; i < size; i++) { 823 elements[i] = s.readObject(); 824 } 825 826 elementData = elements; 827 } else if (size == 0) { 828 elementData = EMPTY_ELEMENTDATA; 829 } else { 830 throw new java.io.InvalidObjectException("Invalid size: " + size); 831 } 832 } 833 834 /** 835 * Returns a list iterator over the elements in this list (in proper 836 * sequence), starting at the specified position in the list. 837 * The specified index indicates the first element that would be 838 * returned by an initial call to {@link ListIterator#next next}. 839 * An initial call to {@link ListIterator#previous previous} would 840 * return the element with the specified index minus one. 841 * 842 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 843 * 844 * @throws IndexOutOfBoundsException {@inheritDoc} 845 */ 846 public ListIterator<E> listIterator(int index) { 847 rangeCheckForAdd(index); 848 return new ListItr(index); 849 } 850 851 /** 852 * Returns a list iterator over the elements in this list (in proper 853 * sequence). 854 * 855 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 856 * 857 * @see #listIterator(int) 858 */ 859 public ListIterator<E> listIterator() { 860 return new ListItr(0); 861 } 862 863 /** 864 * Returns an iterator over the elements in this list in proper sequence. 865 * 866 * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 867 * 868 * @return an iterator over the elements in this list in proper sequence 869 */ 870 public Iterator<E> iterator() { 871 return new Itr(); 872 } 873 874 /** 875 * An optimized version of AbstractList.Itr 876 */ 877 private class Itr implements Iterator<E> { 878 int cursor; // index of next element to return 879 int lastRet = -1; // index of last element returned; -1 if no such 880 int expectedModCount = modCount; 881 882 // prevent creating a synthetic constructor 883 Itr() {} 884 885 public boolean hasNext() { 886 return cursor != size; 887 } 888 889 @SuppressWarnings("unchecked") 890 public E next() { 891 checkForComodification(); 892 int i = cursor; 893 if (i >= size) 894 throw new NoSuchElementException(); 895 Object[] elementData = ArrayList.this.elementData; 896 if (i >= elementData.length) 897 throw new ConcurrentModificationException(); 898 cursor = i + 1; 899 return (E) elementData[lastRet = i]; 900 } 901 902 public void remove() { 903 if (lastRet < 0) 904 throw new IllegalStateException(); 905 checkForComodification(); 906 907 try { 908 ArrayList.this.remove(lastRet); 909 cursor = lastRet; 910 lastRet = -1; 911 expectedModCount = modCount; 912 } catch (IndexOutOfBoundsException ex) { 913 throw new ConcurrentModificationException(); 914 } 915 } 916 917 @Override 918 public void forEachRemaining(Consumer<? super E> action) { 919 Objects.requireNonNull(action); 920 final int size = ArrayList.this.size; 921 int i = cursor; 922 if (i < size) { 923 final Object[] es = elementData; 924 if (i >= es.length) 925 throw new ConcurrentModificationException(); 926 for (; i < size && modCount == expectedModCount; i++) 927 action.accept(elementAt(es, i)); 928 // update once at end to reduce heap write traffic 929 cursor = i; 930 lastRet = i - 1; 931 checkForComodification(); 932 } 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 boolean removeAll(Collection<?> c) { 1120 return batchRemove(c, false); 1121 } 1122 1123 public boolean retainAll(Collection<?> c) { 1124 return batchRemove(c, true); 1125 } 1126 1127 private boolean batchRemove(Collection<?> c, boolean complement) { 1128 checkForComodification(); 1129 int oldSize = root.size; 1130 boolean modified = 1131 root.batchRemove(c, complement, offset, offset + size); 1132 if (modified) 1133 updateSizeAndModCount(root.size - oldSize); 1134 return modified; 1135 } 1136 1137 public boolean removeIf(Predicate<? super E> filter) { 1138 checkForComodification(); 1139 int oldSize = root.size; 1140 boolean modified = root.removeIf(filter, offset, offset + size); 1141 if (modified) 1142 updateSizeAndModCount(root.size - oldSize); 1143 return modified; 1144 } 1145 1146 public Object[] toArray() { 1147 checkForComodification(); 1148 return Arrays.copyOfRange(root.elementData, offset, offset + size); 1149 } 1150 1151 @SuppressWarnings("unchecked") 1152 public <T> T[] toArray(T[] a) { 1153 checkForComodification(); 1154 if (a.length < size) 1155 return (T[]) Arrays.copyOfRange( 1156 root.elementData, offset, offset + size, a.getClass()); 1157 System.arraycopy(root.elementData, offset, a, 0, size); 1158 if (a.length > size) 1159 a[size] = null; 1160 return a; 1161 } 1162 1163 public Iterator<E> iterator() { 1164 return listIterator(); 1165 } 1166 1167 public ListIterator<E> listIterator(int index) { 1168 checkForComodification(); 1169 rangeCheckForAdd(index); 1170 1171 return new ListIterator<E>() { 1172 int cursor = index; 1173 int lastRet = -1; 1174 int expectedModCount = root.modCount; 1175 1176 public boolean hasNext() { 1177 return cursor != SubList.this.size; 1178 } 1179 1180 @SuppressWarnings("unchecked") 1181 public E next() { 1182 checkForComodification(); 1183 int i = cursor; 1184 if (i >= SubList.this.size) 1185 throw new NoSuchElementException(); 1186 Object[] elementData = root.elementData; 1187 if (offset + i >= elementData.length) 1188 throw new ConcurrentModificationException(); 1189 cursor = i + 1; 1190 return (E) elementData[offset + (lastRet = i)]; 1191 } 1192 1193 public boolean hasPrevious() { 1194 return cursor != 0; 1195 } 1196 1197 @SuppressWarnings("unchecked") 1198 public E previous() { 1199 checkForComodification(); 1200 int i = cursor - 1; 1201 if (i < 0) 1202 throw new NoSuchElementException(); 1203 Object[] elementData = root.elementData; 1204 if (offset + i >= elementData.length) 1205 throw new ConcurrentModificationException(); 1206 cursor = i; 1207 return (E) elementData[offset + (lastRet = i)]; 1208 } 1209 1210 public void forEachRemaining(Consumer<? super E> action) { 1211 Objects.requireNonNull(action); 1212 final int size = SubList.this.size; 1213 int i = cursor; 1214 if (i < size) { 1215 final Object[] es = root.elementData; 1216 if (offset + i >= es.length) 1217 throw new ConcurrentModificationException(); 1218 for (; i < size && modCount == expectedModCount; i++) 1219 action.accept(elementAt(es, offset + i)); 1220 // update once at end to reduce heap write traffic 1221 cursor = i; 1222 lastRet = i - 1; 1223 checkForComodification(); 1224 } 1225 } 1226 1227 public int nextIndex() { 1228 return cursor; 1229 } 1230 1231 public int previousIndex() { 1232 return cursor - 1; 1233 } 1234 1235 public void remove() { 1236 if (lastRet < 0) 1237 throw new IllegalStateException(); 1238 checkForComodification(); 1239 1240 try { 1241 SubList.this.remove(lastRet); 1242 cursor = lastRet; 1243 lastRet = -1; 1244 expectedModCount = root.modCount; 1245 } catch (IndexOutOfBoundsException ex) { 1246 throw new ConcurrentModificationException(); 1247 } 1248 } 1249 1250 public void set(E e) { 1251 if (lastRet < 0) 1252 throw new IllegalStateException(); 1253 checkForComodification(); 1254 1255 try { 1256 root.set(offset + lastRet, e); 1257 } catch (IndexOutOfBoundsException ex) { 1258 throw new ConcurrentModificationException(); 1259 } 1260 } 1261 1262 public void add(E e) { 1263 checkForComodification(); 1264 1265 try { 1266 int i = cursor; 1267 SubList.this.add(i, e); 1268 cursor = i + 1; 1269 lastRet = -1; 1270 expectedModCount = root.modCount; 1271 } catch (IndexOutOfBoundsException ex) { 1272 throw new ConcurrentModificationException(); 1273 } 1274 } 1275 1276 final void checkForComodification() { 1277 if (root.modCount != expectedModCount) 1278 throw new ConcurrentModificationException(); 1279 } 1280 }; 1281 } 1282 1283 public List<E> subList(int fromIndex, int toIndex) { 1284 subListRangeCheck(fromIndex, toIndex, size); 1285 return new SubList<>(this, fromIndex, toIndex); 1286 } 1287 1288 private void rangeCheckForAdd(int index) { 1289 if (index < 0 || index > this.size) 1290 throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); 1291 } 1292 1293 private String outOfBoundsMsg(int index) { 1294 return "Index: "+index+", Size: "+this.size; 1295 } 1296 1297 private void checkForComodification() { 1298 if (root.modCount != modCount) 1299 throw new ConcurrentModificationException(); 1300 } 1301 1302 private void updateSizeAndModCount(int sizeChange) { 1303 SubList<E> slist = this; 1304 do { 1305 slist.size += sizeChange; 1306 slist.modCount = root.modCount; 1307 slist = slist.parent; 1308 } while (slist != null); 1309 } 1310 1311 public Spliterator<E> spliterator() { 1312 checkForComodification(); 1313 1314 // ArrayListSpliterator not used here due to late-binding 1315 return new Spliterator<E>() { 1316 private int index = offset; // current index, modified on advance/split 1317 private int fence = -1; // -1 until used; then one past last index 1318 private int expectedModCount; // initialized when fence set 1319 1320 private int getFence() { // initialize fence to size on first use 1321 int hi; // (a specialized variant appears in method forEach) 1322 if ((hi = fence) < 0) { 1323 expectedModCount = modCount; 1324 hi = fence = offset + size; 1325 } 1326 return hi; 1327 } 1328 1329 public ArrayList<E>.ArrayListSpliterator trySplit() { 1330 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; 1331 // ArrayListSpliterator can be used here as the source is already bound 1332 return (lo >= mid) ? null : // divide range in half unless too small 1333 root.new ArrayListSpliterator(lo, index = mid, expectedModCount); 1334 } 1335 1336 public boolean tryAdvance(Consumer<? super E> action) { 1337 Objects.requireNonNull(action); 1338 int hi = getFence(), i = index; 1339 if (i < hi) { 1340 index = i + 1; 1341 @SuppressWarnings("unchecked") E e = (E)root.elementData[i]; 1342 action.accept(e); 1343 if (root.modCount != expectedModCount) 1344 throw new ConcurrentModificationException(); 1345 return true; 1346 } 1347 return false; 1348 } 1349 1350 public void forEachRemaining(Consumer<? super E> action) { 1351 Objects.requireNonNull(action); 1352 int i, hi, mc; // hoist accesses and checks from loop 1353 ArrayList<E> lst = root; 1354 Object[] a; 1355 if ((a = lst.elementData) != null) { 1356 if ((hi = fence) < 0) { 1357 mc = modCount; 1358 hi = offset + size; 1359 } 1360 else 1361 mc = expectedModCount; 1362 if ((i = index) >= 0 && (index = hi) <= a.length) { 1363 for (; i < hi; ++i) { 1364 @SuppressWarnings("unchecked") E e = (E) a[i]; 1365 action.accept(e); 1366 } 1367 if (lst.modCount == mc) 1368 return; 1369 } 1370 } 1371 throw new ConcurrentModificationException(); 1372 } 1373 1374 public long estimateSize() { 1375 return getFence() - index; 1376 } 1377 1378 public int characteristics() { 1379 return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED; 1380 } 1381 }; 1382 } 1383 } 1384 1385 /** 1386 * @throws NullPointerException {@inheritDoc} 1387 */ 1388 @Override 1389 public void forEach(Consumer<? super E> action) { 1390 Objects.requireNonNull(action); 1391 final int expectedModCount = modCount; 1392 final Object[] es = elementData; 1393 final int size = this.size; 1394 for (int i = 0; modCount == expectedModCount && i < size; i++) 1395 action.accept(elementAt(es, i)); 1396 if (modCount != expectedModCount) 1397 throw new ConcurrentModificationException(); 1398 } 1399 1400 /** 1401 * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> 1402 * and <em>fail-fast</em> {@link Spliterator} over the elements in this 1403 * list. 1404 * 1405 * <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, 1406 * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}. 1407 * Overriding implementations should document the reporting of additional 1408 * characteristic values. 1409 * 1410 * @return a {@code Spliterator} over the elements in this list 1411 * @since 1.8 1412 */ 1413 @Override 1414 public Spliterator<E> spliterator() { 1415 return new ArrayListSpliterator(0, -1, 0); 1416 } 1417 1418 /** Index-based split-by-two, lazily initialized Spliterator */ 1419 final class ArrayListSpliterator implements Spliterator<E> { 1420 1421 /* 1422 * If ArrayLists were immutable, or structurally immutable (no 1423 * adds, removes, etc), we could implement their spliterators 1424 * with Arrays.spliterator. Instead we detect as much 1425 * interference during traversal as practical without 1426 * sacrificing much performance. We rely primarily on 1427 * modCounts. These are not guaranteed to detect concurrency 1428 * violations, and are sometimes overly conservative about 1429 * within-thread interference, but detect enough problems to 1430 * be worthwhile in practice. To carry this out, we (1) lazily 1431 * initialize fence and expectedModCount until the latest 1432 * point that we need to commit to the state we are checking 1433 * against; thus improving precision. (This doesn't apply to 1434 * SubLists, that create spliterators with current non-lazy 1435 * values). (2) We perform only a single 1436 * ConcurrentModificationException check at the end of forEach 1437 * (the most performance-sensitive method). When using forEach 1438 * (as opposed to iterators), we can normally only detect 1439 * interference after actions, not before. Further 1440 * CME-triggering checks apply to all other possible 1441 * violations of assumptions for example null or too-small 1442 * elementData array given its size(), that could only have 1443 * occurred due to interference. This allows the inner loop 1444 * of forEach to run without any further checks, and 1445 * simplifies lambda-resolution. While this does entail a 1446 * number of checks, note that in the common case of 1447 * list.stream().forEach(a), no checks or other computation 1448 * occur anywhere other than inside forEach itself. The other 1449 * less-often-used methods cannot take advantage of most of 1450 * these streamlinings. 1451 */ 1452 1453 private int index; // current index, modified on advance/split 1454 private int fence; // -1 until used; then one past last index 1455 private int expectedModCount; // initialized when fence set 1456 1457 /** Creates new spliterator covering the given range. */ 1458 ArrayListSpliterator(int origin, int fence, int expectedModCount) { 1459 this.index = origin; 1460 this.fence = fence; 1461 this.expectedModCount = expectedModCount; 1462 } 1463 1464 private int getFence() { // initialize fence to size on first use 1465 int hi; // (a specialized variant appears in method forEach) 1466 if ((hi = fence) < 0) { 1467 expectedModCount = modCount; 1468 hi = fence = size; 1469 } 1470 return hi; 1471 } 1472 1473 public ArrayListSpliterator trySplit() { 1474 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; 1475 return (lo >= mid) ? null : // divide range in half unless too small 1476 new ArrayListSpliterator(lo, index = mid, expectedModCount); 1477 } 1478 1479 public boolean tryAdvance(Consumer<? super E> action) { 1480 if (action == null) 1481 throw new NullPointerException(); 1482 int hi = getFence(), i = index; 1483 if (i < hi) { 1484 index = i + 1; 1485 @SuppressWarnings("unchecked") E e = (E)elementData[i]; 1486 action.accept(e); 1487 if (modCount != expectedModCount) 1488 throw new ConcurrentModificationException(); 1489 return true; 1490 } 1491 return false; 1492 } 1493 1494 public void forEachRemaining(Consumer<? super E> action) { 1495 int i, hi, mc; // hoist accesses and checks from loop 1496 Object[] a; 1497 if (action == null) 1498 throw new NullPointerException(); 1499 if ((a = elementData) != null) { 1500 if ((hi = fence) < 0) { 1501 mc = modCount; 1502 hi = size; 1503 } 1504 else 1505 mc = expectedModCount; 1506 if ((i = index) >= 0 && (index = hi) <= a.length) { 1507 for (; i < hi; ++i) { 1508 @SuppressWarnings("unchecked") E e = (E) a[i]; 1509 action.accept(e); 1510 } 1511 if (modCount == mc) 1512 return; 1513 } 1514 } 1515 throw new ConcurrentModificationException(); 1516 } 1517 1518 public long estimateSize() { 1519 return getFence() - index; 1520 } 1521 1522 public int characteristics() { 1523 return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED; 1524 } 1525 } 1526 1527 // A tiny bit set implementation 1528 1529 private static long[] nBits(int n) { 1530 return new long[((n - 1) >> 6) + 1]; 1531 } 1532 private static void setBit(long[] bits, int i) { 1533 bits[i >> 6] |= 1L << i; 1534 } 1535 private static boolean isClear(long[] bits, int i) { 1536 return (bits[i >> 6] & (1L << i)) == 0; 1537 } 1538 1539 /** 1540 * @throws NullPointerException {@inheritDoc} 1541 */ 1542 @Override 1543 public boolean removeIf(Predicate<? super E> filter) { 1544 return removeIf(filter, 0, size); 1545 } 1546 1547 /** 1548 * Removes all elements satisfying the given predicate, from index 1549 * i (inclusive) to index end (exclusive). 1550 */ 1551 boolean removeIf(Predicate<? super E> filter, int i, final int end) { 1552 Objects.requireNonNull(filter); 1553 int expectedModCount = modCount; 1554 final Object[] es = elementData; 1555 // Optimize for initial run of survivors 1556 for (; i < end && !filter.test(elementAt(es, i)); i++) 1557 ; 1558 // Tolerate predicates that reentrantly access the collection for 1559 // read (but writers still get CME), so traverse once to find 1560 // elements to delete, a second pass to physically expunge. 1561 if (i < end) { 1562 final int beg = i; 1563 final long[] deathRow = nBits(end - beg); 1564 deathRow[0] = 1L; // set bit 0 1565 for (i = beg + 1; i < end; i++) 1566 if (filter.test(elementAt(es, i))) 1567 setBit(deathRow, i - beg); 1568 if (modCount != expectedModCount) 1569 throw new ConcurrentModificationException(); 1570 modCount++; 1571 int w = beg; 1572 for (i = beg; i < end; i++) 1573 if (isClear(deathRow, i - beg)) 1574 es[w++] = es[i]; 1575 shiftTailOverGap(es, w, end); 1576 return true; 1577 } else { 1578 if (modCount != expectedModCount) 1579 throw new ConcurrentModificationException(); 1580 return false; 1581 } 1582 } 1583 1584 @Override 1585 public void replaceAll(UnaryOperator<E> operator) { 1586 Objects.requireNonNull(operator); 1587 final int expectedModCount = modCount; 1588 final Object[] es = elementData; 1589 final int size = this.size; 1590 for (int i = 0; modCount == expectedModCount && i < size; i++) 1591 es[i] = operator.apply(elementAt(es, i)); 1592 if (modCount != expectedModCount) 1593 throw new ConcurrentModificationException(); 1594 modCount++; 1595 } 1596 1597 @Override 1598 @SuppressWarnings("unchecked") 1599 public void sort(Comparator<? super E> c) { 1600 final int expectedModCount = modCount; 1601 Arrays.sort((E[]) elementData, 0, size, c); 1602 if (modCount != expectedModCount) 1603 throw new ConcurrentModificationException(); 1604 modCount++; 1605 } 1606 1607 void checkInvariants() { 1608 // assert size >= 0; 1609 // assert size == elementData.length || elementData[size] == null; 1610 } 1611 }