ArrayList? add(int index,E element)

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add(E e)方法的代碼

1 /** 2 * Appends the specified element to the end of this list. 3 * 4 * @param e element to be appended to this list 5 * @return <tt>true</tt> (as specified by {@link Collection#add}) 6 */ 7 public boolean add(E e) { 8 ensureCapacityInternal(size + 1); // Increments modCount!! 9 elementData[size++] = e; 10 return true;// 11 }

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add(int index , E element) 方法的代碼

1 /** 2 * Inserts the specified element at the specified position in this 3 * list. Shifts the element currently at that position (if any) and 4 * any subsequent elements to the right (adds one to their indices). 5 * 6 * @param index index at which the specified element is to be inserted 7 * @param element element to be inserted 8 * @throws IndexOutOfBoundsException {@inheritDoc} 9 */ 10 public void add(int index, E element) { 11 rangeCheckForAdd(index);//判斷index是否合法，跳到該方法代碼，如果index>size||index<0 throw new IndexOutOfBoundsExcedption(...見下圖 12 13 ensureCapacityInternal(size + 1); // Increments modCount!! 14 System.arraycopy(elementData, index, elementData, index + 1, 15 size - index);//所有index之后的元素向后移動一位。。 16 elementData[index] = element;//賦值 17 size++;//更新size 18 }

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ArrayList類的代碼

? 1 /* 2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved. 3 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. 4 * 5 * 6 * 7 * 8 * 9 * 10 * 11 * 12 * 13 * 14 * 15 * 16 * 17 * 18 * 19 * 20 * 21 * 22 * 23 * 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 sun.misc.SharedSecrets; 32 33 /** 34 * Resizable-array implementation of the <tt>List</tt> interface. Implements 35 * all optional list operations, and permits all elements, including 36 * <tt>null</tt>. In addition to implementing the <tt>List</tt> 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 * <tt>Vector</tt>, except that it is unsynchronized.) 40 * 41 * <p>The <tt>size</tt>, <tt>isEmpty</tt>, <tt>get</tt>, <tt>set</tt>, 42 * <tt>iterator</tt>, and <tt>listIterator</tt> operations run in constant 43 * time. The <tt>add</tt> 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 <tt>LinkedList</tt> implementation. 47 * 48 * <p>Each <tt>ArrayList</tt> 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 <tt>ArrayList</tt> instance 56 * before adding a large number of elements using the <tt>ensureCapacity</tt> 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 <tt>ArrayList</tt> 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><a name="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>:</a> 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}/../technotes/guides/collections/index.html"> 96 * Java Collections Framework</a>. 97 * 98 * @author Josh Bloch 99 * @author Neal Gafter 100 * @see Collection 101 * @see List 102 * @see LinkedList 103 * @see Vector 104 * @since 1.2 105 */ 106 107 public class ArrayList<E> extends AbstractList<E> 108 implements List<E>, RandomAccess, Cloneable, java.io.Serializable 109 { 110 private static final long serialVersionUID = 8683452581122892189L; 111 112 /** 113 * Default initial capacity. 114 */ 115 private static final int DEFAULT_CAPACITY = 10; 116 117 /** 118 * Shared empty array instance used for empty instances. 119 */ 120 private static final Object[] EMPTY_ELEMENTDATA = {}; 121 122 /** 123 * Shared empty array instance used for default sized empty instances. We 124 * distinguish this from EMPTY_ELEMENTDATA to know how much to inflate when 125 * first element is added. 126 */ 127 private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA = {}; 128 129 /** 130 * The array buffer into which the elements of the ArrayList are stored. 131 * The capacity of the ArrayList is the length of this array buffer. Any 132 * empty ArrayList with elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA 133 * will be expanded to DEFAULT_CAPACITY when the first element is added. 134 */ 135 transient Object[] elementData; // non-private to simplify nested class access 136 137 /** 138 * The size of the ArrayList (the number of elements it contains). 139 * 140 * @serial 141 */ 142 private int size; 143 144 /** 145 * Constructs an empty list with the specified initial capacity. 146 * 147 * @param initialCapacity the initial capacity of the list 148 * @throws IllegalArgumentException if the specified initial capacity 149 * is negative 150 */ 151 public ArrayList(int initialCapacity) { 152 if (initialCapacity > 0) { 153 this.elementData = new Object[initialCapacity]; 154 } else if (initialCapacity == 0) { 155 this.elementData = EMPTY_ELEMENTDATA; 156 } else { 157 throw new IllegalArgumentException("Illegal Capacity: "+ 158 initialCapacity); 159 } 160 } 161 162 /** 163 * Constructs an empty list with an initial capacity of ten. 164 */ 165 public ArrayList() { 166 this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA; 167 } 168 169 /** 170 * Constructs a list containing the elements of the specified 171 * collection, in the order they are returned by the collection's 172 * iterator. 173 * 174 * @param c the collection whose elements are to be placed into this list 175 * @throws NullPointerException if the specified collection is null 176 */ 177 public ArrayList(Collection<? extends E> c) { 178 elementData = c.toArray(); 179 if ((size = elementData.length) != 0) { 180 // c.toArray might (incorrectly) not return Object[] (see 6260652) 181 if (elementData.getClass() != Object[].class) 182 elementData = Arrays.copyOf(elementData, size, Object[].class); 183 } else { 184 // replace with empty array. 185 this.elementData = EMPTY_ELEMENTDATA; 186 } 187 } 188 189 /** 190 * Trims the capacity of this <tt>ArrayList</tt> instance to be the 191 * list's current size. An application can use this operation to minimize 192 * the storage of an <tt>ArrayList</tt> instance. 193 */ 194 public void trimToSize() { 195 modCount++; 196 if (size < elementData.length) { 197 elementData = (size == 0) 198 ? EMPTY_ELEMENTDATA 199 : Arrays.copyOf(elementData, size); 200 } 201 } 202 203 /** 204 * Increases the capacity of this <tt>ArrayList</tt> instance, if 205 * necessary, to ensure that it can hold at least the number of elements 206 * specified by the minimum capacity argument. 207 * 208 * @param minCapacity the desired minimum capacity 209 */ 210 public void ensureCapacity(int minCapacity) { 211 int minExpand = (elementData != DEFAULTCAPACITY_EMPTY_ELEMENTDATA) 212 // any size if not default element table 213 ? 0 214 // larger than default for default empty table. It's already 215 // supposed to be at default size. 216 : DEFAULT_CAPACITY; 217 218 if (minCapacity > minExpand) { 219 ensureExplicitCapacity(minCapacity); 220 } 221 } 222 223 private static int calculateCapacity(Object[] elementData, int minCapacity) { 224 if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA) { 225 return Math.max(DEFAULT_CAPACITY, minCapacity); 226 } 227 return minCapacity; 228 } 229 230 private void ensureCapacityInternal(int minCapacity) { 231 ensureExplicitCapacity(calculateCapacity(elementData, minCapacity)); 232 } 233 234 private void ensureExplicitCapacity(int minCapacity) { 235 modCount++; 236 237 // overflow-conscious code 238 if (minCapacity - elementData.length > 0) 239 grow(minCapacity); 240 } 241 242 /** 243 * The maximum size of array to allocate. 244 * Some VMs reserve some header words in an array. 245 * Attempts to allocate larger arrays may result in 246 * OutOfMemoryError: Requested array size exceeds VM limit 247 */ 248 private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; 249 250 /** 251 * Increases the capacity to ensure that it can hold at least the 252 * number of elements specified by the minimum capacity argument. 253 * 254 * @param minCapacity the desired minimum capacity 255 */ 256 private void grow(int minCapacity) { 257 // overflow-conscious code 258 int oldCapacity = elementData.length; 259 int newCapacity = oldCapacity + (oldCapacity >> 1); 260 if (newCapacity - minCapacity < 0) 261 newCapacity = minCapacity; 262 if (newCapacity - MAX_ARRAY_SIZE > 0) 263 newCapacity = hugeCapacity(minCapacity); 264 // minCapacity is usually close to size, so this is a win: 265 elementData = Arrays.copyOf(elementData, newCapacity); 266 } 267 268 private static int hugeCapacity(int minCapacity) { 269 if (minCapacity < 0) // overflow 270 throw new OutOfMemoryError(); 271 return (minCapacity > MAX_ARRAY_SIZE) ? 272 Integer.MAX_VALUE : 273 MAX_ARRAY_SIZE; 274 } 275 276 /** 277 * Returns the number of elements in this list. 278 * 279 * @return the number of elements in this list 280 */ 281 public int size() { 282 return size; 283 } 284 285 /** 286 * Returns <tt>true</tt> if this list contains no elements. 287 * 288 * @return <tt>true</tt> if this list contains no elements 289 */ 290 public boolean isEmpty() { 291 return size == 0; 292 } 293 294 /** 295 * Returns <tt>true</tt> if this list contains the specified element. 296 * More formally, returns <tt>true</tt> if and only if this list contains 297 * at least one element <tt>e</tt> such that 298 * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>. 299 * 300 * @param o element whose presence in this list is to be tested 301 * @return <tt>true</tt> if this list contains the specified element 302 */ 303 public boolean contains(Object o) { 304 return indexOf(o) >= 0; 305 } 306 307 /** 308 * Returns the index of the first occurrence of the specified element 309 * in this list, or -1 if this list does not contain the element. 310 * More formally, returns the lowest index <tt>i</tt> such that 311 * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>, 312 * or -1 if there is no such index. 313 */ 314 public int indexOf(Object o) { 315 if (o == null) { 316 for (int i = 0; i < size; i++) 317 if (elementData[i]==null) 318 return i; 319 } else { 320 for (int i = 0; i < size; i++) 321 if (o.equals(elementData[i])) 322 return i; 323 } 324 return -1; 325 } 326 327 /** 328 * Returns the index of the last occurrence of the specified element 329 * in this list, or -1 if this list does not contain the element. 330 * More formally, returns the highest index <tt>i</tt> such that 331 * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>, 332 * or -1 if there is no such index. 333 */ 334 public int lastIndexOf(Object o) { 335 if (o == null) { 336 for (int i = size-1; i >= 0; i--) 337 if (elementData[i]==null) 338 return i; 339 } else { 340 for (int i = size-1; i >= 0; i--) 341 if (o.equals(elementData[i])) 342 return i; 343 } 344 return -1; 345 } 346 347 /** 348 * Returns a shallow copy of this <tt>ArrayList</tt> instance. (The 349 * elements themselves are not copied.) 350 * 351 * @return a clone of this <tt>ArrayList</tt> instance 352 */ 353 public Object clone() { 354 try { 355 ArrayList<?> v = (ArrayList<?>) super.clone(); 356 v.elementData = Arrays.copyOf(elementData, size); 357 v.modCount = 0; 358 return v; 359 } catch (CloneNotSupportedException e) { 360 // this shouldn't happen, since we are Cloneable 361 throw new InternalError(e); 362 } 363 } 364 365 /** 366 * Returns an array containing all of the elements in this list 367 * in proper sequence (from first to last element). 368 * 369 * <p>The returned array will be "safe" in that no references to it are 370 * maintained by this list. (In other words, this method must allocate 371 * a new array). The caller is thus free to modify the returned array. 372 * 373 * <p>This method acts as bridge between array-based and collection-based 374 * APIs. 375 * 376 * @return an array containing all of the elements in this list in 377 * proper sequence 378 */ 379 public Object[] toArray() { 380 return Arrays.copyOf(elementData, size); 381 } 382 383 /** 384 * Returns an array containing all of the elements in this list in proper 385 * sequence (from first to last element); the runtime type of the returned 386 * array is that of the specified array. If the list fits in the 387 * specified array, it is returned therein. Otherwise, a new array is 388 * allocated with the runtime type of the specified array and the size of 389 * this list. 390 * 391 * <p>If the list fits in the specified array with room to spare 392 * (i.e., the array has more elements than the list), the element in 393 * the array immediately following the end of the collection is set to 394 * <tt>null</tt>. (This is useful in determining the length of the 395 * list <i>only</i> if the caller knows that the list does not contain 396 * any null elements.) 397 * 398 * @param a the array into which the elements of the list are to 399 * be stored, if it is big enough; otherwise, a new array of the 400 * same runtime type is allocated for this purpose. 401 * @return an array containing the elements of the list 402 * @throws ArrayStoreException if the runtime type of the specified array 403 * is not a supertype of the runtime type of every element in 404 * this list 405 * @throws NullPointerException if the specified array is null 406 */ 407 @SuppressWarnings("unchecked") 408 public <T> T[] toArray(T[] a) { 409 if (a.length < size) 410 // Make a new array of a's runtime type, but my contents: 411 return (T[]) Arrays.copyOf(elementData, size, a.getClass()); 412 System.arraycopy(elementData, 0, a, 0, size); 413 if (a.length > size) 414 a[size] = null; 415 return a; 416 } 417 418 // Positional Access Operations 419 420 @SuppressWarnings("unchecked") 421 E elementData(int index) { 422 return (E) elementData[index]; 423 } 424 425 /** 426 * Returns the element at the specified position in this list. 427 * 428 * @param index index of the element to return 429 * @return the element at the specified position in this list 430 * @throws IndexOutOfBoundsException {@inheritDoc} 431 */ 432 public E get(int index) { 433 rangeCheck(index); 434 435 return elementData(index); 436 } 437 438 /** 439 * Replaces the element at the specified position in this list with 440 * the specified element. 441 * 442 * @param index index of the element to replace 443 * @param element element to be stored at the specified position 444 * @return the element previously at the specified position 445 * @throws IndexOutOfBoundsException {@inheritDoc} 446 */ 447 public E set(int index, E element) { 448 rangeCheck(index); 449 450 E oldValue = elementData(index); 451 elementData[index] = element; 452 return oldValue; 453 } 454 455 /** 456 * Appends the specified element to the end of this list. 457 * 458 * @param e element to be appended to this list 459 * @return <tt>true</tt> (as specified by {@link Collection#add}) 460 */ 461 public boolean add(E e) { 462 ensureCapacityInternal(size + 1); // Increments modCount!! 463 elementData[size++] = e; 464 return true; 465 } 466 467 /** 468 * Inserts the specified element at the specified position in this 469 * list. Shifts the element currently at that position (if any) and 470 * any subsequent elements to the right (adds one to their indices). 471 * 472 * @param index index at which the specified element is to be inserted 473 * @param element element to be inserted 474 * @throws IndexOutOfBoundsException {@inheritDoc} 475 */ 476 public void add(int index, E element) { 477 rangeCheckForAdd(index); 478 479 ensureCapacityInternal(size + 1); // Increments modCount!! 480 System.arraycopy(elementData, index, elementData, index + 1, 481 size - index); 482 elementData[index] = element; 483 size++; 484 } 485 486 /** 487 * Removes the element at the specified position in this list. 488 * Shifts any subsequent elements to the left (subtracts one from their 489 * indices). 490 * 491 * @param index the index of the element to be removed 492 * @return the element that was removed from the list 493 * @throws IndexOutOfBoundsException {@inheritDoc} 494 */ 495 public E remove(int index) { 496 rangeCheck(index); 497 498 modCount++; 499 E oldValue = elementData(index); 500 501 int numMoved = size - index - 1; 502 if (numMoved > 0) 503 System.arraycopy(elementData, index+1, elementData, index, 504 numMoved); 505 elementData[--size] = null; // clear to let GC do its work 506 507 return oldValue; 508 } 509 510 /** 511 * Removes the first occurrence of the specified element from this list, 512 * if it is present. If the list does not contain the element, it is 513 * unchanged. More formally, removes the element with the lowest index 514 * <tt>i</tt> such that 515 * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt> 516 * (if such an element exists). Returns <tt>true</tt> if this list 517 * contained the specified element (or equivalently, if this list 518 * changed as a result of the call). 519 * 520 * @param o element to be removed from this list, if present 521 * @return <tt>true</tt> if this list contained the specified element 522 */ 523 public boolean remove(Object o) { 524 if (o == null) { 525 for (int index = 0; index < size; index++) 526 if (elementData[index] == null) { 527 fastRemove(index); 528 return true; 529 } 530 } else { 531 for (int index = 0; index < size; index++) 532 if (o.equals(elementData[index])) { 533 fastRemove(index); 534 return true; 535 } 536 } 537 return false; 538 } 539 540 /* 541 * Private remove method that skips bounds checking and does not 542 * return the value removed. 543 */ 544 private void fastRemove(int index) { 545 modCount++; 546 int numMoved = size - index - 1; 547 if (numMoved > 0) 548 System.arraycopy(elementData, index+1, elementData, index, 549 numMoved); 550 elementData[--size] = null; // clear to let GC do its work 551 } 552 553 /** 554 * Removes all of the elements from this list. The list will 555 * be empty after this call returns. 556 */ 557 public void clear() { 558 modCount++; 559 560 // clear to let GC do its work 561 for (int i = 0; i < size; i++) 562 elementData[i] = null; 563 564 size = 0; 565 } 566 567 /** 568 * Appends all of the elements in the specified collection to the end of 569 * this list, in the order that they are returned by the 570 * specified collection's Iterator. The behavior of this operation is 571 * undefined if the specified collection is modified while the operation 572 * is in progress. (This implies that the behavior of this call is 573 * undefined if the specified collection is this list, and this 574 * list is nonempty.) 575 * 576 * @param c collection containing elements to be added to this list 577 * @return <tt>true</tt> if this list changed as a result of the call 578 * @throws NullPointerException if the specified collection is null 579 */ 580 public boolean addAll(Collection<? extends E> c) { 581 Object[] a = c.toArray(); 582 int numNew = a.length; 583 ensureCapacityInternal(size + numNew); // Increments modCount 584 System.arraycopy(a, 0, elementData, size, numNew); 585 size += numNew; 586 return numNew != 0; 587 } 588 589 /** 590 * Inserts all of the elements in the specified collection into this 591 * list, starting at the specified position. Shifts the element 592 * currently at that position (if any) and any subsequent elements to 593 * the right (increases their indices). The new elements will appear 594 * in the list in the order that they are returned by the 595 * specified collection's iterator. 596 * 597 * @param index index at which to insert the first element from the 598 * specified collection 599 * @param c collection containing elements to be added to this list 600 * @return <tt>true</tt> if this list changed as a result of the call 601 * @throws IndexOutOfBoundsException {@inheritDoc} 602 * @throws NullPointerException if the specified collection is null 603 */ 604 public boolean addAll(int index, Collection<? extends E> c) { 605 rangeCheckForAdd(index); 606 607 Object[] a = c.toArray(); 608 int numNew = a.length; 609 ensureCapacityInternal(size + numNew); // Increments modCount 610 611 int numMoved = size - index; 612 if (numMoved > 0) 613 System.arraycopy(elementData, index, elementData, index + numNew, 614 numMoved); 615 616 System.arraycopy(a, 0, elementData, index, numNew); 617 size += numNew; 618 return numNew != 0; 619 } 620 621 /** 622 * Removes from this list all of the elements whose index is between 623 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. 624 * Shifts any succeeding elements to the left (reduces their index). 625 * This call shortens the list by {@code (toIndex - fromIndex)} elements. 626 * (If {@code toIndex==fromIndex}, this operation has no effect.) 627 * 628 * @throws IndexOutOfBoundsException if {@code fromIndex} or 629 * {@code toIndex} is out of range 630 * ({@code fromIndex < 0 || 631 * fromIndex >= size() || 632 * toIndex > size() || 633 * toIndex < fromIndex}) 634 */ 635 protected void removeRange(int fromIndex, int toIndex) { 636 modCount++; 637 int numMoved = size - toIndex; 638 System.arraycopy(elementData, toIndex, elementData, fromIndex, 639 numMoved); 640 641 // clear to let GC do its work 642 int newSize = size - (toIndex-fromIndex); 643 for (int i = newSize; i < size; i++) { 644 elementData[i] = null; 645 } 646 size = newSize; 647 } 648 649 /** 650 * Checks if the given index is in range. If not, throws an appropriate 651 * runtime exception. This method does *not* check if the index is 652 * negative: It is always used immediately prior to an array access, 653 * which throws an ArrayIndexOutOfBoundsException if index is negative. 654 */ 655 private void rangeCheck(int index) { 656 if (index >= size) 657 throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); 658 } 659 660 /** 661 * A version of rangeCheck used by add and addAll. 662 */ 663 private void rangeCheckForAdd(int index) { 664 if (index > size || index < 0) 665 throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); 666 } 667 668 /** 669 * Constructs an IndexOutOfBoundsException detail message. 670 * Of the many possible refactorings of the error handling code, 671 * this "outlining" performs best with both server and client VMs. 672 */ 673 private String outOfBoundsMsg(int index) { 674 return "Index: "+index+", Size: "+size; 675 } 676 677 /** 678 * Removes from this list all of its elements that are contained in the 679 * specified collection. 680 * 681 * @param c collection containing elements to be removed from this list 682 * @return {@code true} if this list changed as a result of the call 683 * @throws ClassCastException if the class of an element of this list 684 * is incompatible with the specified collection 685 * (<a href="Collection.html#optional-restrictions">optional</a>) 686 * @throws NullPointerException if this list contains a null element and the 687 * specified collection does not permit null elements 688 * (<a href="Collection.html#optional-restrictions">optional</a>), 689 * or if the specified collection is null 690 * @see Collection#contains(Object) 691 */ 692 public boolean removeAll(Collection<?> c) { 693 Objects.requireNonNull(c); 694 return batchRemove(c, false); 695 } 696 697 /** 698 * Retains only the elements in this list that are contained in the 699 * specified collection. In other words, removes from this list all 700 * of its elements that are not contained in the specified collection. 701 * 702 * @param c collection containing elements to be retained in this list 703 * @return {@code true} if this list changed as a result of the call 704 * @throws ClassCastException if the class of an element of this list 705 * is incompatible with the specified collection 706 * (<a href="Collection.html#optional-restrictions">optional</a>) 707 * @throws NullPointerException if this list contains a null element and the 708 * specified collection does not permit null elements 709 * (<a href="Collection.html#optional-restrictions">optional</a>), 710 * or if the specified collection is null 711 * @see Collection#contains(Object) 712 */ 713 public boolean retainAll(Collection<?> c) { 714 Objects.requireNonNull(c); 715 return batchRemove(c, true); 716 } 717 718 private boolean batchRemove(Collection<?> c, boolean complement) { 719 final Object[] elementData = this.elementData; 720 int r = 0, w = 0; 721 boolean modified = false; 722 try { 723 for (; r < size; r++) 724 if (c.contains(elementData[r]) == complement) 725 elementData[w++] = elementData[r]; 726 } finally { 727 // Preserve behavioral compatibility with AbstractCollection, 728 // even if c.contains() throws. 729 if (r != size) { 730 System.arraycopy(elementData, r, 731 elementData, w, 732 size - r); 733 w += size - r; 734 } 735 if (w != size) { 736 // clear to let GC do its work 737 for (int i = w; i < size; i++) 738 elementData[i] = null; 739 modCount += size - w; 740 size = w; 741 modified = true; 742 } 743 } 744 return modified; 745 } 746 747 /** 748 * Save the state of the <tt>ArrayList</tt> instance to a stream (that 749 * is, serialize it). 750 * 751 * @serialData The length of the array backing the <tt>ArrayList</tt> 752 * instance is emitted (int), followed by all of its elements 753 * (each an <tt>Object</tt>) in the proper order. 754 */ 755 private void writeObject(java.io.ObjectOutputStream s) 756 throws java.io.IOException{ 757 // Write out element count, and any hidden stuff 758 int expectedModCount = modCount; 759 s.defaultWriteObject(); 760 761 // Write out size as capacity for behavioural compatibility with clone() 762 s.writeInt(size); 763 764 // Write out all elements in the proper order. 765 for (int i=0; i<size; i++) { 766 s.writeObject(elementData[i]); 767 } 768 769 if (modCount != expectedModCount) { 770 throw new ConcurrentModificationException(); 771 } 772 } 773 774 /** 775 * Reconstitute the <tt>ArrayList</tt> instance from a stream (that is, 776 * deserialize it). 777 */ 778 private void readObject(java.io.ObjectInputStream s) 779 throws java.io.IOException, ClassNotFoundException { 780 elementData = EMPTY_ELEMENTDATA; 781 782 // Read in size, and any hidden stuff 783 s.defaultReadObject(); 784 785 // Read in capacity 786 s.readInt(); // ignored 787 788 if (size > 0) { 789 // be like clone(), allocate array based upon size not capacity 790 int capacity = calculateCapacity(elementData, size); 791 SharedSecrets.getJavaOISAccess().checkArray(s, Object[].class, capacity); 792 ensureCapacityInternal(size); 793 794 Object[] a = elementData; 795 // Read in all elements in the proper order. 796 for (int i=0; i<size; i++) { 797 a[i] = s.readObject(); 798 } 799 } 800 } 801 802 /** 803 * Returns a list iterator over the elements in this list (in proper 804 * sequence), starting at the specified position in the list. 805 * The specified index indicates the first element that would be 806 * returned by an initial call to {@link ListIterator#next next}. 807 * An initial call to {@link ListIterator#previous previous} would 808 * return the element with the specified index minus one. 809 * 810 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 811 * 812 * @throws IndexOutOfBoundsException {@inheritDoc} 813 */ 814 public ListIterator<E> listIterator(int index) { 815 if (index < 0 || index > size) 816 throw new IndexOutOfBoundsException("Index: "+index); 817 return new ListItr(index); 818 } 819 820 /** 821 * Returns a list iterator over the elements in this list (in proper 822 * sequence). 823 * 824 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 825 * 826 * @see #listIterator(int) 827 */ 828 public ListIterator<E> listIterator() { 829 return new ListItr(0); 830 } 831 832 /** 833 * Returns an iterator over the elements in this list in proper sequence. 834 * 835 * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 836 * 837 * @return an iterator over the elements in this list in proper sequence 838 */ 839 public Iterator<E> iterator() { 840 return new Itr(); 841 } 842 843 /** 844 * An optimized version of AbstractList.Itr 845 */ 846 private class Itr implements Iterator<E> { 847 int cursor; // index of next element to return 848 int lastRet = -1; // index of last element returned; -1 if no such 849 int expectedModCount = modCount; 850 851 Itr() {} 852 853 public boolean hasNext() { 854 return cursor != size; 855 } 856 857 @SuppressWarnings("unchecked") 858 public E next() { 859 checkForComodification(); 860 int i = cursor; 861 if (i >= size) 862 throw new NoSuchElementException(); 863 Object[] elementData = ArrayList.this.elementData; 864 if (i >= elementData.length) 865 throw new ConcurrentModificationException(); 866 cursor = i + 1; 867 return (E) elementData[lastRet = i]; 868 } 869 870 public void remove() { 871 if (lastRet < 0) 872 throw new IllegalStateException(); 873 checkForComodification(); 874 875 try { 876 ArrayList.this.remove(lastRet); 877 cursor = lastRet; 878 lastRet = -1; 879 expectedModCount = modCount; 880 } catch (IndexOutOfBoundsException ex) { 881 throw new ConcurrentModificationException(); 882 } 883 } 884 885 @Override 886 @SuppressWarnings("unchecked") 887 public void forEachRemaining(Consumer<? super E> consumer) { 888 Objects.requireNonNull(consumer); 889 final int size = ArrayList.this.size; 890 int i = cursor; 891 if (i >= size) { 892 return; 893 } 894 final Object[] elementData = ArrayList.this.elementData; 895 if (i >= elementData.length) { 896 throw new ConcurrentModificationException(); 897 } 898 while (i != size && modCount == expectedModCount) { 899 consumer.accept((E) elementData[i++]); 900 } 901 // update once at end of iteration to reduce heap write traffic 902 cursor = i; 903 lastRet = i - 1; 904 checkForComodification(); 905 } 906 907 final void checkForComodification() { 908 if (modCount != expectedModCount) 909 throw new ConcurrentModificationException(); 910 } 911 } 912 913 /** 914 * An optimized version of AbstractList.ListItr 915 */ 916 private class ListItr extends Itr implements ListIterator<E> { 917 ListItr(int index) { 918 super(); 919 cursor = index; 920 } 921 922 public boolean hasPrevious() { 923 return cursor != 0; 924 } 925 926 public int nextIndex() { 927 return cursor; 928 } 929 930 public int previousIndex() { 931 return cursor - 1; 932 } 933 934 @SuppressWarnings("unchecked") 935 public E previous() { 936 checkForComodification(); 937 int i = cursor - 1; 938 if (i < 0) 939 throw new NoSuchElementException(); 940 Object[] elementData = ArrayList.this.elementData; 941 if (i >= elementData.length) 942 throw new ConcurrentModificationException(); 943 cursor = i; 944 return (E) elementData[lastRet = i]; 945 } 946 947 public void set(E e) { 948 if (lastRet < 0) 949 throw new IllegalStateException(); 950 checkForComodification(); 951 952 try { 953 ArrayList.this.set(lastRet, e); 954 } catch (IndexOutOfBoundsException ex) { 955 throw new ConcurrentModificationException(); 956 } 957 } 958 959 public void add(E e) { 960 checkForComodification(); 961 962 try { 963 int i = cursor; 964 ArrayList.this.add(i, e); 965 cursor = i + 1; 966 lastRet = -1; 967 expectedModCount = modCount; 968 } catch (IndexOutOfBoundsException ex) { 969 throw new ConcurrentModificationException(); 970 } 971 } 972 } 973 974 /** 975 * Returns a view of the portion of this list between the specified 976 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. (If 977 * {@code fromIndex} and {@code toIndex} are equal, the returned list is 978 * empty.) The returned list is backed by this list, so non-structural 979 * changes in the returned list are reflected in this list, and vice-versa. 980 * The returned list supports all of the optional list operations. 981 * 982 * <p>This method eliminates the need for explicit range operations (of 983 * the sort that commonly exist for arrays). Any operation that expects 984 * a list can be used as a range operation by passing a subList view 985 * instead of a whole list. For example, the following idiom 986 * removes a range of elements from a list: 987 * <pre> 988 * list.subList(from, to).clear(); 989 * </pre> 990 * Similar idioms may be constructed for {@link #indexOf(Object)} and 991 * {@link #lastIndexOf(Object)}, and all of the algorithms in the 992 * {@link Collections} class can be applied to a subList. 993 * 994 * <p>The semantics of the list returned by this method become undefined if 995 * the backing list (i.e., this list) is <i>structurally modified</i> in 996 * any way other than via the returned list. (Structural modifications are 997 * those that change the size of this list, or otherwise perturb it in such 998 * a fashion that iterations in progress may yield incorrect results.) 999 * 1000 * @throws IndexOutOfBoundsException {@inheritDoc} 1001 * @throws IllegalArgumentException {@inheritDoc} 1002 */ 1003 public List<E> subList(int fromIndex, int toIndex) { 1004 subListRangeCheck(fromIndex, toIndex, size); 1005 return new SubList(this, 0, fromIndex, toIndex); 1006 } 1007 1008 static void subListRangeCheck(int fromIndex, int toIndex, int size) { 1009 if (fromIndex < 0) 1010 throw new IndexOutOfBoundsException("fromIndex = " + fromIndex); 1011 if (toIndex > size) 1012 throw new IndexOutOfBoundsException("toIndex = " + toIndex); 1013 if (fromIndex > toIndex) 1014 throw new IllegalArgumentException("fromIndex(" + fromIndex + 1015 ") > toIndex(" + toIndex + ")"); 1016 } 1017 1018 private class SubList extends AbstractList<E> implements RandomAccess { 1019 private final AbstractList<E> parent; 1020 private final int parentOffset; 1021 private final int offset; 1022 int size; 1023 1024 SubList(AbstractList<E> parent, 1025 int offset, int fromIndex, int toIndex) { 1026 this.parent = parent; 1027 this.parentOffset = fromIndex; 1028 this.offset = offset + fromIndex; 1029 this.size = toIndex - fromIndex; 1030 this.modCount = ArrayList.this.modCount; 1031 } 1032 1033 public E set(int index, E e) { 1034 rangeCheck(index); 1035 checkForComodification(); 1036 E oldValue = ArrayList.this.elementData(offset + index); 1037 ArrayList.this.elementData[offset + index] = e; 1038 return oldValue; 1039 } 1040 1041 public E get(int index) { 1042 rangeCheck(index); 1043 checkForComodification(); 1044 return ArrayList.this.elementData(offset + index); 1045 } 1046 1047 public int size() { 1048 checkForComodification(); 1049 return this.size; 1050 } 1051 1052 public void add(int index, E e) { 1053 rangeCheckForAdd(index); 1054 checkForComodification(); 1055 parent.add(parentOffset + index, e); 1056 this.modCount = parent.modCount; 1057 this.size++; 1058 } 1059 1060 public E remove(int index) { 1061 rangeCheck(index); 1062 checkForComodification(); 1063 E result = parent.remove(parentOffset + index); 1064 this.modCount = parent.modCount; 1065 this.size--; 1066 return result; 1067 } 1068 1069 protected void removeRange(int fromIndex, int toIndex) { 1070 checkForComodification(); 1071 parent.removeRange(parentOffset + fromIndex, 1072 parentOffset + toIndex); 1073 this.modCount = parent.modCount; 1074 this.size -= toIndex - fromIndex; 1075 } 1076 1077 public boolean addAll(Collection<? extends E> c) { 1078 return addAll(this.size, c); 1079 } 1080 1081 public boolean addAll(int index, Collection<? extends E> c) { 1082 rangeCheckForAdd(index); 1083 int cSize = c.size(); 1084 if (cSize==0) 1085 return false; 1086 1087 checkForComodification(); 1088 parent.addAll(parentOffset + index, c); 1089 this.modCount = parent.modCount; 1090 this.size += cSize; 1091 return true; 1092 } 1093 1094 public Iterator<E> iterator() { 1095 return listIterator(); 1096 } 1097 1098 public ListIterator<E> listIterator(final int index) { 1099 checkForComodification(); 1100 rangeCheckForAdd(index); 1101 final int offset = this.offset; 1102 1103 return new ListIterator<E>() { 1104 int cursor = index; 1105 int lastRet = -1; 1106 int expectedModCount = ArrayList.this.modCount; 1107 1108 public boolean hasNext() { 1109 return cursor != SubList.this.size; 1110 } 1111 1112 @SuppressWarnings("unchecked") 1113 public E next() { 1114 checkForComodification(); 1115 int i = cursor; 1116 if (i >= SubList.this.size) 1117 throw new NoSuchElementException(); 1118 Object[] elementData = ArrayList.this.elementData; 1119 if (offset + i >= elementData.length) 1120 throw new ConcurrentModificationException(); 1121 cursor = i + 1; 1122 return (E) elementData[offset + (lastRet = i)]; 1123 } 1124 1125 public boolean hasPrevious() { 1126 return cursor != 0; 1127 } 1128 1129 @SuppressWarnings("unchecked") 1130 public E previous() { 1131 checkForComodification(); 1132 int i = cursor - 1; 1133 if (i < 0) 1134 throw new NoSuchElementException(); 1135 Object[] elementData = ArrayList.this.elementData; 1136 if (offset + i >= elementData.length) 1137 throw new ConcurrentModificationException(); 1138 cursor = i; 1139 return (E) elementData[offset + (lastRet = i)]; 1140 } 1141 1142 @SuppressWarnings("unchecked") 1143 public void forEachRemaining(Consumer<? super E> consumer) { 1144 Objects.requireNonNull(consumer); 1145 final int size = SubList.this.size; 1146 int i = cursor; 1147 if (i >= size) { 1148 return; 1149 } 1150 final Object[] elementData = ArrayList.this.elementData; 1151 if (offset + i >= elementData.length) { 1152 throw new ConcurrentModificationException(); 1153 } 1154 while (i != size && modCount == expectedModCount) { 1155 consumer.accept((E) elementData[offset + (i++)]); 1156 } 1157 // update once at end of iteration to reduce heap write traffic 1158 lastRet = cursor = i; 1159 checkForComodification(); 1160 } 1161 1162 public int nextIndex() { 1163 return cursor; 1164 } 1165 1166 public int previousIndex() { 1167 return cursor - 1; 1168 } 1169 1170 public void remove() { 1171 if (lastRet < 0) 1172 throw new IllegalStateException(); 1173 checkForComodification(); 1174 1175 try { 1176 SubList.this.remove(lastRet); 1177 cursor = lastRet; 1178 lastRet = -1; 1179 expectedModCount = ArrayList.this.modCount; 1180 } catch (IndexOutOfBoundsException ex) { 1181 throw new ConcurrentModificationException(); 1182 } 1183 } 1184 1185 public void set(E e) { 1186 if (lastRet < 0) 1187 throw new IllegalStateException(); 1188 checkForComodification(); 1189 1190 try { 1191 ArrayList.this.set(offset + lastRet, e); 1192 } catch (IndexOutOfBoundsException ex) { 1193 throw new ConcurrentModificationException(); 1194 } 1195 } 1196 1197 public void add(E e) { 1198 checkForComodification(); 1199 1200 try { 1201 int i = cursor; 1202 SubList.this.add(i, e); 1203 cursor = i + 1; 1204 lastRet = -1; 1205 expectedModCount = ArrayList.this.modCount; 1206 } catch (IndexOutOfBoundsException ex) { 1207 throw new ConcurrentModificationException(); 1208 } 1209 } 1210 1211 final void checkForComodification() { 1212 if (expectedModCount != ArrayList.this.modCount) 1213 throw new ConcurrentModificationException(); 1214 } 1215 }; 1216 } 1217 1218 public List<E> subList(int fromIndex, int toIndex) { 1219 subListRangeCheck(fromIndex, toIndex, size); 1220 return new SubList(this, offset, fromIndex, toIndex); 1221 } 1222 1223 private void rangeCheck(int index) { 1224 if (index < 0 || index >= this.size) 1225 throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); 1226 } 1227 1228 private void rangeCheckForAdd(int index) { 1229 if (index < 0 || index > this.size) 1230 throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); 1231 } 1232 1233 private String outOfBoundsMsg(int index) { 1234 return "Index: "+index+", Size: "+this.size; 1235 } 1236 1237 private void checkForComodification() { 1238 if (ArrayList.this.modCount != this.modCount) 1239 throw new ConcurrentModificationException(); 1240 } 1241 1242 public Spliterator<E> spliterator() { 1243 checkForComodification(); 1244 return new ArrayListSpliterator<E>(ArrayList.this, offset, 1245 offset + this.size, this.modCount); 1246 } 1247 } 1248 1249 @Override 1250 public void forEach(Consumer<? super E> action) { 1251 Objects.requireNonNull(action); 1252 final int expectedModCount = modCount; 1253 @SuppressWarnings("unchecked") 1254 final E[] elementData = (E[]) this.elementData; 1255 final int size = this.size; 1256 for (int i=0; modCount == expectedModCount && i < size; i++) { 1257 action.accept(elementData[i]); 1258 } 1259 if (modCount != expectedModCount) { 1260 throw new ConcurrentModificationException(); 1261 } 1262 } 1263 1264 /** 1265 * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> 1266 * and <em>fail-fast</em> {@link Spliterator} over the elements in this 1267 * list. 1268 * 1269 * <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, 1270 * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}. 1271 * Overriding implementations should document the reporting of additional 1272 * characteristic values. 1273 * 1274 * @return a {@code Spliterator} over the elements in this list 1275 * @since 1.8 1276 */ 1277 @Override 1278 public Spliterator<E> spliterator() { 1279 return new ArrayListSpliterator<>(this, 0, -1, 0); 1280 } 1281 1282 /** Index-based split-by-two, lazily initialized Spliterator */ 1283 static final class ArrayListSpliterator<E> implements Spliterator<E> { 1284 1285 /* 1286 * If ArrayLists were immutable, or structurally immutable (no 1287 * adds, removes, etc), we could implement their spliterators 1288 * with Arrays.spliterator. Instead we detect as much 1289 * interference during traversal as practical without 1290 * sacrificing much performance. We rely primarily on 1291 * modCounts. These are not guaranteed to detect concurrency 1292 * violations, and are sometimes overly conservative about 1293 * within-thread interference, but detect enough problems to 1294 * be worthwhile in practice. To carry this out, we (1) lazily 1295 * initialize fence and expectedModCount until the latest 1296 * point that we need to commit to the state we are checking 1297 * against; thus improving precision. (This doesn't apply to 1298 * SubLists, that create spliterators with current non-lazy 1299 * values). (2) We perform only a single 1300 * ConcurrentModificationException check at the end of forEach 1301 * (the most performance-sensitive method). When using forEach 1302 * (as opposed to iterators), we can normally only detect 1303 * interference after actions, not before. Further 1304 * CME-triggering checks apply to all other possible 1305 * violations of assumptions for example null or too-small 1306 * elementData array given its size(), that could only have 1307 * occurred due to interference. This allows the inner loop 1308 * of forEach to run without any further checks, and 1309 * simplifies lambda-resolution. While this does entail a 1310 * number of checks, note that in the common case of 1311 * list.stream().forEach(a), no checks or other computation 1312 * occur anywhere other than inside forEach itself. The other 1313 * less-often-used methods cannot take advantage of most of 1314 * these streamlinings. 1315 */ 1316 1317 private final ArrayList<E> list; 1318 private int index; // current index, modified on advance/split 1319 private int fence; // -1 until used; then one past last index 1320 private int expectedModCount; // initialized when fence set 1321 1322 /** Create new spliterator covering the given range */ 1323 ArrayListSpliterator(ArrayList<E> list, int origin, int fence, 1324 int expectedModCount) { 1325 this.list = list; // OK if null unless traversed 1326 this.index = origin; 1327 this.fence = fence; 1328 this.expectedModCount = expectedModCount; 1329 } 1330 1331 private int getFence() { // initialize fence to size on first use 1332 int hi; // (a specialized variant appears in method forEach) 1333 ArrayList<E> lst; 1334 if ((hi = fence) < 0) { 1335 if ((lst = list) == null) 1336 hi = fence = 0; 1337 else { 1338 expectedModCount = lst.modCount; 1339 hi = fence = lst.size; 1340 } 1341 } 1342 return hi; 1343 } 1344 1345 public ArrayListSpliterator<E> trySplit() { 1346 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; 1347 return (lo >= mid) ? null : // divide range in half unless too small 1348 new ArrayListSpliterator<E>(list, lo, index = mid, 1349 expectedModCount); 1350 } 1351 1352 public boolean tryAdvance(Consumer<? super E> action) { 1353 if (action == null) 1354 throw new NullPointerException(); 1355 int hi = getFence(), i = index; 1356 if (i < hi) { 1357 index = i + 1; 1358 @SuppressWarnings("unchecked") E e = (E)list.elementData[i]; 1359 action.accept(e); 1360 if (list.modCount != expectedModCount) 1361 throw new ConcurrentModificationException(); 1362 return true; 1363 } 1364 return false; 1365 } 1366 1367 public void forEachRemaining(Consumer<? super E> action) { 1368 int i, hi, mc; // hoist accesses and checks from loop 1369 ArrayList<E> lst; Object[] a; 1370 if (action == null) 1371 throw new NullPointerException(); 1372 if ((lst = list) != null && (a = lst.elementData) != null) { 1373 if ((hi = fence) < 0) { 1374 mc = lst.modCount; 1375 hi = lst.size; 1376 } 1377 else 1378 mc = expectedModCount; 1379 if ((i = index) >= 0 && (index = hi) <= a.length) { 1380 for (; i < hi; ++i) { 1381 @SuppressWarnings("unchecked") E e = (E) a[i]; 1382 action.accept(e); 1383 } 1384 if (lst.modCount == mc) 1385 return; 1386 } 1387 } 1388 throw new ConcurrentModificationException(); 1389 } 1390 1391 public long estimateSize() { 1392 return (long) (getFence() - index); 1393 } 1394 1395 public int characteristics() { 1396 return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED; 1397 } 1398 } 1399 1400 @Override 1401 public boolean removeIf(Predicate<? super E> filter) { 1402 Objects.requireNonNull(filter); 1403 // figure out which elements are to be removed 1404 // any exception thrown from the filter predicate at this stage 1405 // will leave the collection unmodified 1406 int removeCount = 0; 1407 final BitSet removeSet = new BitSet(size); 1408 final int expectedModCount = modCount; 1409 final int size = this.size; 1410 for (int i=0; modCount == expectedModCount && i < size; i++) { 1411 @SuppressWarnings("unchecked") 1412 final E element = (E) elementData[i]; 1413 if (filter.test(element)) { 1414 removeSet.set(i); 1415 removeCount++; 1416 } 1417 } 1418 if (modCount != expectedModCount) { 1419 throw new ConcurrentModificationException(); 1420 } 1421 1422 // shift surviving elements left over the spaces left by removed elements 1423 final boolean anyToRemove = removeCount > 0; 1424 if (anyToRemove) { 1425 final int newSize = size - removeCount; 1426 for (int i=0, j=0; (i < size) && (j < newSize); i++, j++) { 1427 i = removeSet.nextClearBit(i); 1428 elementData[j] = elementData[i]; 1429 } 1430 for (int k=newSize; k < size; k++) { 1431 elementData[k] = null; // Let gc do its work 1432 } 1433 this.size = newSize; 1434 if (modCount != expectedModCount) { 1435 throw new ConcurrentModificationException(); 1436 } 1437 modCount++; 1438 } 1439 1440 return anyToRemove; 1441 } 1442 1443 @Override 1444 @SuppressWarnings("unchecked") 1445 public void replaceAll(UnaryOperator<E> operator) { 1446 Objects.requireNonNull(operator); 1447 final int expectedModCount = modCount; 1448 final int size = this.size; 1449 for (int i=0; modCount == expectedModCount && i < size; i++) { 1450 elementData[i] = operator.apply((E) elementData[i]); 1451 } 1452 if (modCount != expectedModCount) { 1453 throw new ConcurrentModificationException(); 1454 } 1455 modCount++; 1456 } 1457 1458 @Override 1459 @SuppressWarnings("unchecked") 1460 public void sort(Comparator<? super E> c) { 1461 final int expectedModCount = modCount; 1462 Arrays.sort((E[]) elementData, 0, size, c); 1463 if (modCount != expectedModCount) { 1464 throw new ConcurrentModificationException(); 1465 } 1466 modCount++; 1467 } 1468 }

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轉載于:https://www.cnblogs.com/yangzihong/p/10122341.html

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