1 /*
2 * Copyright (c) 1997, 2013, 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 /**
29 * Resizable-array implementation of the <tt>List</tt> interface. Implements
30 * all optional list operations, and permits all elements, including
31 * <tt>null</tt>. In addition to implementing the <tt>List</tt> interface,
32 * this class provides methods to manipulate the size of the array that is
33 * used internally to store the list. (This class is roughly equivalent to
34 * <tt>Vector</tt>, except that it is unsynchronized.)
35 *
36 * <p>The <tt>size</tt>, <tt>isEmpty</tt>, <tt>get</tt>, <tt>set</tt>,
37 * <tt>iterator</tt>, and <tt>listIterator</tt> operations run in constant
38 * time. The <tt>add</tt> operation runs in <i>amortized constant time</i>,
39 * that is, adding n elements requires O(n) time. All of the other operations
40 * run in linear time (roughly speaking). The constant factor is low compared
41 * to that for the <tt>LinkedList</tt> implementation.
42 *
43 * <p>Each <tt>ArrayList</tt> instance has a <i>capacity</i>. The capacity is
44 * the size of the array used to store the elements in the list. It is always
45 * at least as large as the list size. As elements are added to an ArrayList,
46 * its capacity grows automatically. The details of the growth policy are not
47 * specified beyond the fact that adding an element has constant amortized
48 * time cost.
49 *
50 * <p>An application can increase the capacity of an <tt>ArrayList</tt> instance
51 * before adding a large number of elements using the <tt>ensureCapacity</tt>
52 * operation. This may reduce the amount of incremental reallocation.
53 *
54 * <p><strong>Note that this implementation is not synchronized.</strong>
55 * If multiple threads access an <tt>ArrayList</tt> instance concurrently,
56 * and at least one of the threads modifies the list structurally, it
57 * <i>must</i> be synchronized externally. (A structural modification is
58 * any operation that adds or deletes one or more elements, or explicitly
59 * resizes the backing array; merely setting the value of an element is not
60 * a structural modification.) This is typically accomplished by
61 * synchronizing on some object that naturally encapsulates the list.
62 *
63 * If no such object exists, the list should be "wrapped" using the
64 * {@link Collections#synchronizedList Collections.synchronizedList}
65 * method. This is best done at creation time, to prevent accidental
66 * unsynchronized access to the list:<pre>
67 * List list = Collections.synchronizedList(new ArrayList(...));</pre>
68 *
69 * <p><a name="fail-fast"/>
70 * The iterators returned by this class's {@link #iterator() iterator} and
71 * {@link #listIterator(int) listIterator} methods are <em>fail-fast</em>:
72 * if the list is structurally modified at any time after the iterator is
73 * created, in any way except through the iterator's own
74 * {@link ListIterator#remove() remove} or
75 * {@link ListIterator#add(Object) add} methods, the iterator will throw a
76 * {@link ConcurrentModificationException}. Thus, in the face of
77 * concurrent modification, the iterator fails quickly and cleanly, rather
78 * than risking arbitrary, non-deterministic behavior at an undetermined
79 * time in the future.
80 *
81 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
82 * as it is, generally speaking, impossible to make any hard guarantees in the
83 * presence of unsynchronized concurrent modification. Fail-fast iterators
84 * throw {@code ConcurrentModificationException} on a best-effort basis.
85 * Therefore, it would be wrong to write a program that depended on this
86 * exception for its correctness: <i>the fail-fast behavior of iterators
87 * should be used only to detect bugs.</i>
88 *
89 * <p>This class is a member of the
90 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
91 * Java Collections Framework</a>.
92 *
93 * @author Josh Bloch
94 * @author Neal Gafter
95 * @see Collection
96 * @see List
97 * @see LinkedList
98 * @see Vector
99 * @since 1.2
100 */
101
102 public class ArrayList<E> extends AbstractList<E>
103 implements List<E>, RandomAccess, Cloneable, java.io.Serializable
104 {
105 private static final long serialVersionUID = 8683452581122892189L;
106
107 /**
108 * Shared empty array instance used for empty instances.
109 */
110 private static final Object EMPTY_ELEMENTDATA[] = new Object[0];
111
112 /**
113 * The array buffer into which the elements of the ArrayList are stored.
114 * The capacity of the ArrayList is the length of this array buffer.
115 */
116 private transient Object[] elementData;
117
118 /**
119 * The size of the ArrayList (the number of elements it contains).
120 *
121 * @serial
122 */
123 private int size;
124
125 /**
126 * Constructs an empty list with the specified initial capacity.
127 *
128 * @param initialCapacity the initial capacity of the list
129 * @throws IllegalArgumentException if the specified initial capacity
130 * is negative
131 */
132 public ArrayList(int initialCapacity) {
133 super();
134 if (initialCapacity < 0)
135 throw new IllegalArgumentException("Illegal Capacity: "+
136 initialCapacity);
137 this.elementData = new Object[initialCapacity];
138 }
139
140 /**
141 * Constructs an empty list with an initial capacity of ten.
142 */
143 public ArrayList() {
144 super();
145 this.elementData = EMPTY_ELEMENTDATA;
146 }
147
148 /**
149 * Constructs a list containing the elements of the specified
150 * collection, in the order they are returned by the collection's
151 * iterator.
152 *
153 * @param c the collection whose elements are to be placed into this list
154 * @throws NullPointerException if the specified collection is null
155 */
156 public ArrayList(Collection<? extends E> c) {
157 elementData = c.toArray();
158 size = elementData.length;
159 // c.toArray might (incorrectly) not return Object[] (see 6260652)
160 if (elementData.getClass() != Object[].class)
161 elementData = Arrays.copyOf(elementData, size, Object[].class);
162 }
163
164 /**
165 * Trims the capacity of this <tt>ArrayList</tt> instance to be the
166 * list's current size. An application can use this operation to minimize
167 * the storage of an <tt>ArrayList</tt> instance.
168 */
169 public void trimToSize() {
170 modCount++;
171 if (size < elementData.length) {
172 elementData = Arrays.copyOf(elementData, size);
173 }
174 }
175
176 /**
177 * Increases the capacity of this <tt>ArrayList</tt> instance, if
178 * necessary, to ensure that it can hold at least the number of elements
179 * specified by the minimum capacity argument.
180 *
181 * @param minCapacity the desired minimum capacity
182 */
183 public void ensureCapacity(int minCapacity) {
184 if (minCapacity > 0)
185 ensureExplicitCapacity(minCapacity);
186 }
187
188 private void ensureCapacityInternal(int minCapacity) {
189 if(elementData == EMPTY_ELEMENTDATA) {
190 minCapacity = Math.max(10, minCapacity);
191 }
192
193 ensureExplicitCapacity(minCapacity);
194 }
195
196 private void ensureExplicitCapacity(int minCapacity) {
197 modCount++;
198
199 // overflow-conscious code
200 if (minCapacity - elementData.length > 0)
201 grow(minCapacity);
202 }
203
204 /**
205 * The maximum size of array to allocate.
206 * Some VMs reserve some header words in an array.
207 * Attempts to allocate larger arrays may result in
208 * OutOfMemoryError: Requested array size exceeds VM limit
209 */
210 private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
211
212 /**
213 * Increases the capacity to ensure that it can hold at least the
214 * number of elements specified by the minimum capacity argument.
215 *
216 * @param minCapacity the desired minimum capacity
217 */
218 private void grow(int minCapacity) {
219 // overflow-conscious code
220 int oldCapacity = elementData.length;
221 int newCapacity = oldCapacity + (oldCapacity >> 1);
222 if (newCapacity - minCapacity < 0)
223 newCapacity = minCapacity;
224 if (newCapacity - MAX_ARRAY_SIZE > 0)
225 newCapacity = hugeCapacity(minCapacity);
226 // minCapacity is usually close to size, so this is a win:
227 elementData = Arrays.copyOf(elementData, newCapacity);
228 }
229
230 private static int hugeCapacity(int minCapacity) {
231 if (minCapacity < 0) // overflow
232 throw new OutOfMemoryError();
233 return (minCapacity > MAX_ARRAY_SIZE) ?
234 Integer.MAX_VALUE :
235 MAX_ARRAY_SIZE;
236 }
237
238 /**
239 * Returns the number of elements in this list.
240 *
241 * @return the number of elements in this list
242 */
243 public int size() {
244 return size;
245 }
246
247 /**
248 * Returns <tt>true</tt> if this list contains no elements.
249 *
250 * @return <tt>true</tt> if this list contains no elements
251 */
252 public boolean isEmpty() {
253 return size == 0;
254 }
255
256 /**
257 * Returns <tt>true</tt> if this list contains the specified element.
258 * More formally, returns <tt>true</tt> if and only if this list contains
259 * at least one element <tt>e</tt> such that
260 * <tt>(o==null ? e==null : o.equals(e))</tt>.
261 *
262 * @param o element whose presence in this list is to be tested
263 * @return <tt>true</tt> if this list contains the specified element
264 */
265 public boolean contains(Object o) {
266 return indexOf(o) >= 0;
267 }
268
269 /**
270 * Returns the index of the first occurrence of the specified element
271 * in this list, or -1 if this list does not contain the element.
272 * More formally, returns the lowest index <tt>i</tt> such that
273 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
274 * or -1 if there is no such index.
275 */
276 public int indexOf(Object o) {
277 if (o == null) {
278 for (int i = 0; i < size; i++)
279 if (elementData[i]==null)
280 return i;
281 } else {
282 for (int i = 0; i < size; i++)
283 if (o.equals(elementData[i]))
284 return i;
285 }
286 return -1;
287 }
288
289 /**
290 * Returns the index of the last occurrence of the specified element
291 * in this list, or -1 if this list does not contain the element.
292 * More formally, returns the highest index <tt>i</tt> such that
293 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
294 * or -1 if there is no such index.
295 */
296 public int lastIndexOf(Object o) {
297 if (o == null) {
298 for (int i = size-1; i >= 0; i--)
299 if (elementData[i]==null)
300 return i;
301 } else {
302 for (int i = size-1; i >= 0; i--)
303 if (o.equals(elementData[i]))
304 return i;
305 }
306 return -1;
307 }
308
309 /**
310 * Returns a shallow copy of this <tt>ArrayList</tt> instance. (The
311 * elements themselves are not copied.)
312 *
313 * @return a clone of this <tt>ArrayList</tt> instance
314 */
315 public Object clone() {
316 try {
317 ArrayList<?> v = (ArrayList<?>) super.clone();
318 v.elementData = Arrays.copyOf(elementData, size);
319 v.modCount = 0;
320 return v;
321 } catch (CloneNotSupportedException e) {
322 // this shouldn't happen, since we are Cloneable
323 throw new InternalError(e);
324 }
325 }
326
327 /**
328 * Returns an array containing all of the elements in this list
329 * in proper sequence (from first to last element).
330 *
331 * <p>The returned array will be "safe" in that no references to it are
332 * maintained by this list. (In other words, this method must allocate
333 * a new array). The caller is thus free to modify the returned array.
334 *
335 * <p>This method acts as bridge between array-based and collection-based
336 * APIs.
337 *
338 * @return an array containing all of the elements in this list in
339 * proper sequence
340 */
341 public Object[] toArray() {
342 return Arrays.copyOf(elementData, size);
343 }
344
345 /**
346 * Returns an array containing all of the elements in this list in proper
347 * sequence (from first to last element); the runtime type of the returned
348 * array is that of the specified array. If the list fits in the
349 * specified array, it is returned therein. Otherwise, a new array is
350 * allocated with the runtime type of the specified array and the size of
351 * this list.
352 *
353 * <p>If the list fits in the specified array with room to spare
354 * (i.e., the array has more elements than the list), the element in
355 * the array immediately following the end of the collection is set to
356 * <tt>null</tt>. (This is useful in determining the length of the
357 * list <i>only</i> if the caller knows that the list does not contain
358 * any null elements.)
359 *
360 * @param a the array into which the elements of the list are to
361 * be stored, if it is big enough; otherwise, a new array of the
362 * same runtime type is allocated for this purpose.
363 * @return an array containing the elements of the list
364 * @throws ArrayStoreException if the runtime type of the specified array
365 * is not a supertype of the runtime type of every element in
366 * this list
367 * @throws NullPointerException if the specified array is null
368 */
369 @SuppressWarnings("unchecked")
370 public <T> T[] toArray(T[] a) {
371 if (a.length < size)
372 // Make a new array of a's runtime type, but my contents:
373 return (T[]) Arrays.copyOf(elementData, size, a.getClass());
374 System.arraycopy(elementData, 0, a, 0, size);
375 if (a.length > size)
376 a[size] = null;
377 return a;
378 }
379
380 // Positional Access Operations
381
382 @SuppressWarnings("unchecked")
383 E elementData(int index) {
384 return (E) elementData[index];
385 }
386
387 /**
388 * Returns the element at the specified position in this list.
389 *
390 * @param index index of the element to return
391 * @return the element at the specified position in this list
392 * @throws IndexOutOfBoundsException {@inheritDoc}
393 */
394 public E get(int index) {
395 rangeCheck(index);
396
397 return elementData(index);
398 }
399
400 /**
401 * Replaces the element at the specified position in this list with
402 * the specified element.
403 *
404 * @param index index of the element to replace
405 * @param element element to be stored at the specified position
406 * @return the element previously at the specified position
407 * @throws IndexOutOfBoundsException {@inheritDoc}
408 */
409 public E set(int index, E element) {
410 rangeCheck(index);
411
412 E oldValue = elementData(index);
413 elementData[index] = element;
414 return oldValue;
415 }
416
417 /**
418 * Appends the specified element to the end of this list.
419 *
420 * @param e element to be appended to this list
421 * @return <tt>true</tt> (as specified by {@link Collection#add})
422 */
423 public boolean add(E e) {
424 ensureCapacityInternal(size + 1); // Increments modCount!!
425 elementData[size++] = e;
426 return true;
427 }
428
429 /**
430 * Inserts the specified element at the specified position in this
431 * list. Shifts the element currently at that position (if any) and
432 * any subsequent elements to the right (adds one to their indices).
433 *
434 * @param index index at which the specified element is to be inserted
435 * @param element element to be inserted
436 * @throws IndexOutOfBoundsException {@inheritDoc}
437 */
438 public void add(int index, E element) {
439 rangeCheckForAdd(index);
440
441 ensureCapacityInternal(size + 1); // Increments modCount!!
442 System.arraycopy(elementData, index, elementData, index + 1,
443 size - index);
444 elementData[index] = element;
445 size++;
446 }
447
448 /**
449 * Removes the element at the specified position in this list.
450 * Shifts any subsequent elements to the left (subtracts one from their
451 * indices).
452 *
453 * @param index the index of the element to be removed
454 * @return the element that was removed from the list
455 * @throws IndexOutOfBoundsException {@inheritDoc}
456 */
457 public E remove(int index) {
458 rangeCheck(index);
459
460 modCount++;
461 E oldValue = elementData(index);
462
463 int numMoved = size - index - 1;
464 if (numMoved > 0)
465 System.arraycopy(elementData, index+1, elementData, index,
466 numMoved);
467 elementData[--size] = null; // Let gc do its work
468
469 return oldValue;
470 }
471
472 /**
473 * Removes the first occurrence of the specified element from this list,
474 * if it is present. If the list does not contain the element, it is
475 * unchanged. More formally, removes the element with the lowest index
476 * <tt>i</tt> such that
477 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>
478 * (if such an element exists). Returns <tt>true</tt> if this list
479 * contained the specified element (or equivalently, if this list
480 * changed as a result of the call).
481 *
482 * @param o element to be removed from this list, if present
483 * @return <tt>true</tt> if this list contained the specified element
484 */
485 public boolean remove(Object o) {
486 if (o == null) {
487 for (int index = 0; index < size; index++)
488 if (elementData[index] == null) {
489 fastRemove(index);
490 return true;
491 }
492 } else {
493 for (int index = 0; index < size; index++)
494 if (o.equals(elementData[index])) {
495 fastRemove(index);
496 return true;
497 }
498 }
499 return false;
500 }
501
502 /*
503 * Private remove method that skips bounds checking and does not
504 * return the value removed.
505 */
506 private void fastRemove(int index) {
507 modCount++;
508 int numMoved = size - index - 1;
509 if (numMoved > 0)
510 System.arraycopy(elementData, index+1, elementData, index,
511 numMoved);
512 elementData[--size] = null; // Let gc do its work
513 }
514
515 /**
516 * Removes all of the elements from this list. The list will
517 * be empty after this call returns.
518 */
519 public void clear() {
520 modCount++;
521
522 // Let gc do its work
523 Arrays.fill(elementData, null);
524
525 size = 0;
526 }
527
528 /**
529 * Appends all of the elements in the specified collection to the end of
530 * this list, in the order that they are returned by the
531 * specified collection's Iterator. The behavior of this operation is
532 * undefined if the specified collection is modified while the operation
533 * is in progress. (This implies that the behavior of this call is
534 * undefined if the specified collection is this list, and this
535 * list is nonempty.)
536 *
537 * @param c collection containing elements to be added to this list
538 * @return <tt>true</tt> if this list changed as a result of the call
539 * @throws NullPointerException if the specified collection is null
540 */
541 public boolean addAll(Collection<? extends E> c) {
542 Object[] a = c.toArray();
543 int numNew = a.length;
544 ensureCapacityInternal(size + numNew); // Increments modCount
545 System.arraycopy(a, 0, elementData, size, numNew);
546 size += numNew;
547 return numNew != 0;
548 }
549
550 /**
551 * Inserts all of the elements in the specified collection into this
552 * list, starting at the specified position. Shifts the element
553 * currently at that position (if any) and any subsequent elements to
554 * the right (increases their indices). The new elements will appear
555 * in the list in the order that they are returned by the
556 * specified collection's iterator.
557 *
558 * @param index index at which to insert the first element from the
559 * specified collection
560 * @param c collection containing elements to be added to this list
561 * @return <tt>true</tt> if this list changed as a result of the call
562 * @throws IndexOutOfBoundsException {@inheritDoc}
563 * @throws NullPointerException if the specified collection is null
564 */
565 public boolean addAll(int index, Collection<? extends E> c) {
566 rangeCheckForAdd(index);
567
568 Object[] a = c.toArray();
569 int numNew = a.length;
570 ensureCapacityInternal(size + numNew); // Increments modCount
571
572 int numMoved = size - index;
573 if (numMoved > 0)
574 System.arraycopy(elementData, index, elementData, index + numNew,
575 numMoved);
576
577 System.arraycopy(a, 0, elementData, index, numNew);
578 size += numNew;
579 return numNew != 0;
580 }
581
582 /**
583 * Removes from this list all of the elements whose index is between
584 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
585 * Shifts any succeeding elements to the left (reduces their index).
586 * This call shortens the list by {@code (toIndex - fromIndex)} elements.
587 * (If {@code toIndex==fromIndex}, this operation has no effect.)
588 *
589 * @throws IndexOutOfBoundsException if {@code fromIndex} or
590 * {@code toIndex} is out of range
591 * ({@code fromIndex < 0 ||
592 * fromIndex >= size() ||
593 * toIndex > size() ||
594 * toIndex < fromIndex})
595 */
596 protected void removeRange(int fromIndex, int toIndex) {
597 modCount++;
598 int numMoved = size - toIndex;
599 System.arraycopy(elementData, toIndex, elementData, fromIndex,
600 numMoved);
601
602 // Let gc do its work
603 int newSize = size - (toIndex-fromIndex);
604 Arrays.fill(elementData, newSize, size, null);
605 size = newSize;
606 }
607
608 /**
609 * Checks if the given index is in range. If not, throws an appropriate
610 * runtime exception. This method does *not* check if the index is
611 * negative: It is always used immediately prior to an array access,
612 * which throws an ArrayIndexOutOfBoundsException if index is negative.
613 */
614 private void rangeCheck(int index) {
615 if (index >= size)
616 throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
617 }
618
619 /**
620 * A version of rangeCheck used by add and addAll.
621 */
622 private void rangeCheckForAdd(int index) {
623 if (index > size || index < 0)
624 throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
625 }
626
627 /**
628 * Constructs an IndexOutOfBoundsException detail message.
629 * Of the many possible refactorings of the error handling code,
630 * this "outlining" performs best with both server and client VMs.
631 */
632 private String outOfBoundsMsg(int index) {
633 return "Index: "+index+", Size: "+size;
634 }
635
636 /**
637 * Removes from this list all of its elements that are contained in the
638 * specified collection.
639 *
640 * @param c collection containing elements to be removed from this list
641 * @return {@code true} if this list changed as a result of the call
642 * @throws ClassCastException if the class of an element of this list
643 * is incompatible with the specified collection
644 * (<a href="Collection.html#optional-restrictions">optional</a>)
645 * @throws NullPointerException if this list contains a null element and the
646 * specified collection does not permit null elements
647 * (<a href="Collection.html#optional-restrictions">optional</a>),
648 * or if the specified collection is null
649 * @see Collection#contains(Object)
650 */
651 public boolean removeAll(Collection<?> c) {
652 return batchRemove(c, false);
653 }
654
655 /**
656 * Retains only the elements in this list that are contained in the
657 * specified collection. In other words, removes from this list all
658 * of its elements that are not contained in the specified collection.
659 *
660 * @param c collection containing elements to be retained in this list
661 * @return {@code true} if this list changed as a result of the call
662 * @throws ClassCastException if the class of an element of this list
663 * is incompatible with the specified collection
664 * (<a href="Collection.html#optional-restrictions">optional</a>)
665 * @throws NullPointerException if this list contains a null element and the
666 * specified collection does not permit null elements
667 * (<a href="Collection.html#optional-restrictions">optional</a>),
668 * or if the specified collection is null
669 * @see Collection#contains(Object)
670 */
671 public boolean retainAll(Collection<?> c) {
672 return batchRemove(c, true);
673 }
674
675 private boolean batchRemove(Collection<?> c, boolean complement) {
676 final Object[] elementData = this.elementData;
677 int r = 0, w = 0;
678 boolean modified = false;
679 try {
680 for (; r < size; r++)
681 if (c.contains(elementData[r]) == complement)
682 elementData[w++] = elementData[r];
683 } finally {
684 // Preserve behavioral compatibility with AbstractCollection,
685 // even if c.contains() throws.
686 if (r != size) {
687 System.arraycopy(elementData, r,
688 elementData, w,
689 size - r);
690 w += size - r;
691 }
692 if (w != size) {
693 // Let gc do its work
694 Arrays.fill(elementData, w, size, null);
695 modCount += size - w;
696 size = w;
697 modified = true;
698 }
699 }
700 return modified;
701 }
702
703 /**
704 * Save the state of the <tt>ArrayList</tt> instance to a stream (that
705 * is, serialize it).
706 *
707 * @serialData The length of the array backing the <tt>ArrayList</tt>
708 * instance is emitted (int), followed by all of its elements
709 * (each an <tt>Object</tt>) in the proper order.
710 */
711 private void writeObject(java.io.ObjectOutputStream s)
712 throws java.io.IOException{
713 // Write out element count, and any hidden stuff
714 int expectedModCount = modCount;
715 s.defaultWriteObject();
716
717 // Write out array length
718 s.writeInt((elementData == EMPTY_ELEMENTDATA) ? 10 : elementData.length);
719
720 // Write out all elements in the proper order.
721 for (int i=0; i<size; i++)
722 s.writeObject(elementData[i]);
723
724 if (modCount != expectedModCount) {
725 throw new ConcurrentModificationException();
726 }
727 }
728
729 /**
730 * Reconstitute the <tt>ArrayList</tt> instance from a stream (that is,
731 * deserialize it).
732 */
733 private void readObject(java.io.ObjectInputStream s)
734 throws java.io.IOException, ClassNotFoundException {
735 // Read in size, and any hidden stuff
736 s.defaultReadObject();
737
738 // Read in array length
739 int initialCapacity = s.readInt();
740 elementData = EMPTY_ELEMENTDATA;
741
742 if((size > 0) || (initialCapacity != 10)) {
743 // allocate array based upon size.
744 ensureCapacityInternal(size);
745 }
746
747 Object[] a = elementData;
748 // Read in all elements in the proper order.
749 for (int i=0; i<size; i++)
750 a[i] = s.readObject();
751 }
752
753 /**
754 * Returns a list iterator over the elements in this list (in proper
755 * sequence), starting at the specified position in the list.
756 * The specified index indicates the first element that would be
757 * returned by an initial call to {@link ListIterator#next next}.
758 * An initial call to {@link ListIterator#previous previous} would
759 * return the element with the specified index minus one.
760 *
761 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
762 *
763 * @throws IndexOutOfBoundsException {@inheritDoc}
764 */
765 public ListIterator<E> listIterator(int index) {
766 if (index < 0 || index > size)
767 throw new IndexOutOfBoundsException("Index: "+index);
768 return new ListItr(index);
769 }
770
771 /**
772 * Returns a list iterator over the elements in this list (in proper
773 * sequence).
774 *
775 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
776 *
777 * @see #listIterator(int)
778 */
779 public ListIterator<E> listIterator() {
780 return new ListItr(0);
781 }
782
783 /**
784 * Returns an iterator over the elements in this list in proper sequence.
785 *
786 * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
787 *
788 * @return an iterator over the elements in this list in proper sequence
789 */
790 public Iterator<E> iterator() {
791 return new Itr();
792 }
793
794 /**
795 * An optimized version of AbstractList.Itr
796 */
797 private class Itr implements Iterator<E> {
798 int cursor; // index of next element to return
799 int lastRet = -1; // index of last element returned; -1 if no such
800 int expectedModCount = modCount;
801
802 public boolean hasNext() {
803 return cursor != size;
804 }
805
806 @SuppressWarnings("unchecked")
807 public E next() {
808 checkForComodification();
809 int i = cursor;
810 if (i >= size)
811 throw new NoSuchElementException();
812 Object[] elementData = ArrayList.this.elementData;
813 if (i >= elementData.length)
814 throw new ConcurrentModificationException();
815 cursor = i + 1;
816 return (E) elementData[lastRet = i];
817 }
818
819 public void remove() {
820 if (lastRet < 0)
821 throw new IllegalStateException();
822 checkForComodification();
823
824 try {
825 ArrayList.this.remove(lastRet);
826 cursor = lastRet;
827 lastRet = -1;
828 expectedModCount = modCount;
829 } catch (IndexOutOfBoundsException ex) {
830 throw new ConcurrentModificationException();
831 }
832 }
833
834 final void checkForComodification() {
835 if (modCount != expectedModCount)
836 throw new ConcurrentModificationException();
837 }
838 }
839
840 /**
841 * An optimized version of AbstractList.ListItr
842 */
843 private class ListItr extends Itr implements ListIterator<E> {
844 ListItr(int index) {
845 super();
846 cursor = index;
847 }
848
849 public boolean hasPrevious() {
850 return cursor != 0;
851 }
852
853 public int nextIndex() {
854 return cursor;
855 }
856
857 public int previousIndex() {
858 return cursor - 1;
859 }
860
861 @SuppressWarnings("unchecked")
862 public E previous() {
863 checkForComodification();
864 int i = cursor - 1;
865 if (i < 0)
866 throw new NoSuchElementException();
867 Object[] elementData = ArrayList.this.elementData;
868 if (i >= elementData.length)
869 throw new ConcurrentModificationException();
870 cursor = i;
871 return (E) elementData[lastRet = i];
872 }
873
874 public void set(E e) {
875 if (lastRet < 0)
876 throw new IllegalStateException();
877 checkForComodification();
878
879 try {
880 ArrayList.this.set(lastRet, e);
881 } catch (IndexOutOfBoundsException ex) {
882 throw new ConcurrentModificationException();
883 }
884 }
885
886 public void add(E e) {
887 checkForComodification();
888
889 try {
890 int i = cursor;
891 ArrayList.this.add(i, e);
892 cursor = i + 1;
893 lastRet = -1;
894 expectedModCount = modCount;
895 } catch (IndexOutOfBoundsException ex) {
896 throw new ConcurrentModificationException();
897 }
898 }
899 }
900
901 /**
902 * Returns a view of the portion of this list between the specified
903 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. (If
904 * {@code fromIndex} and {@code toIndex} are equal, the returned list is
905 * empty.) The returned list is backed by this list, so non-structural
906 * changes in the returned list are reflected in this list, and vice-versa.
907 * The returned list supports all of the optional list operations.
908 *
909 * <p>This method eliminates the need for explicit range operations (of
910 * the sort that commonly exist for arrays). Any operation that expects
911 * a list can be used as a range operation by passing a subList view
912 * instead of a whole list. For example, the following idiom
913 * removes a range of elements from a list:
914 * <pre>
915 * list.subList(from, to).clear();
916 * </pre>
917 * Similar idioms may be constructed for {@link #indexOf(Object)} and
918 * {@link #lastIndexOf(Object)}, and all of the algorithms in the
919 * {@link Collections} class can be applied to a subList.
920 *
921 * <p>The semantics of the list returned by this method become undefined if
922 * the backing list (i.e., this list) is <i>structurally modified</i> in
923 * any way other than via the returned list. (Structural modifications are
924 * those that change the size of this list, or otherwise perturb it in such
925 * a fashion that iterations in progress may yield incorrect results.)
926 *
927 * @throws IndexOutOfBoundsException {@inheritDoc}
928 * @throws IllegalArgumentException {@inheritDoc}
929 */
930 public List<E> subList(int fromIndex, int toIndex) {
931 subListRangeCheck(fromIndex, toIndex, size);
932 return new SubList(this, 0, fromIndex, toIndex);
933 }
934
935 static void subListRangeCheck(int fromIndex, int toIndex, int size) {
936 if (fromIndex < 0)
937 throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
938 if (toIndex > size)
939 throw new IndexOutOfBoundsException("toIndex = " + toIndex);
940 if (fromIndex > toIndex)
941 throw new IllegalArgumentException("fromIndex(" + fromIndex +
942 ") > toIndex(" + toIndex + ")");
943 }
944
945 private class SubList extends AbstractList<E> implements RandomAccess {
946 private final AbstractList<E> parent;
947 private final int parentOffset;
948 private final int offset;
949 int size;
950
951 SubList(AbstractList<E> parent,
952 int offset, int fromIndex, int toIndex) {
953 this.parent = parent;
954 this.parentOffset = fromIndex;
955 this.offset = offset + fromIndex;
956 this.size = toIndex - fromIndex;
957 this.modCount = ArrayList.this.modCount;
958 }
959
960 public E set(int index, E e) {
961 rangeCheck(index);
962 checkForComodification();
963 E oldValue = ArrayList.this.elementData(offset + index);
964 ArrayList.this.elementData[offset + index] = e;
965 return oldValue;
966 }
967
968 public E get(int index) {
969 rangeCheck(index);
970 checkForComodification();
971 return ArrayList.this.elementData(offset + index);
972 }
973
974 public int size() {
975 checkForComodification();
976 return this.size;
977 }
978
979 public void add(int index, E e) {
980 rangeCheckForAdd(index);
981 checkForComodification();
982 parent.add(parentOffset + index, e);
983 this.modCount = parent.modCount;
984 this.size++;
985 }
986
987 public E remove(int index) {
988 rangeCheck(index);
989 checkForComodification();
990 E result = parent.remove(parentOffset + index);
991 this.modCount = parent.modCount;
992 this.size--;
993 return result;
994 }
995
996 protected void removeRange(int fromIndex, int toIndex) {
997 checkForComodification();
998 parent.removeRange(parentOffset + fromIndex,
999 parentOffset + toIndex);
1000 this.modCount = parent.modCount;
1001 this.size -= toIndex - fromIndex;
1002 }
1003
1004 public boolean addAll(Collection<? extends E> c) {
1005 return addAll(this.size, c);
1006 }
1007
1008 public boolean addAll(int index, Collection<? extends E> c) {
1009 rangeCheckForAdd(index);
1010 int cSize = c.size();
1011 if (cSize==0)
1012 return false;
1013
1014 checkForComodification();
1015 parent.addAll(parentOffset + index, c);
1016 this.modCount = parent.modCount;
1017 this.size += cSize;
1018 return true;
1019 }
1020
1021 public Iterator<E> iterator() {
1022 return listIterator();
1023 }
1024
1025 public ListIterator<E> listIterator(final int index) {
1026 checkForComodification();
1027 rangeCheckForAdd(index);
1028 final int offset = this.offset;
1029
1030 return new ListIterator<E>() {
1031 int cursor = index;
1032 int lastRet = -1;
1033 int expectedModCount = ArrayList.this.modCount;
1034
1035 public boolean hasNext() {
1036 return cursor != SubList.this.size;
1037 }
1038
1039 @SuppressWarnings("unchecked")
1040 public E next() {
1041 checkForComodification();
1042 int i = cursor;
1043 if (i >= SubList.this.size)
1044 throw new NoSuchElementException();
1045 Object[] elementData = ArrayList.this.elementData;
1046 if (offset + i >= elementData.length)
1047 throw new ConcurrentModificationException();
1048 cursor = i + 1;
1049 return (E) elementData[offset + (lastRet = i)];
1050 }
1051
1052 public boolean hasPrevious() {
1053 return cursor != 0;
1054 }
1055
1056 @SuppressWarnings("unchecked")
1057 public E previous() {
1058 checkForComodification();
1059 int i = cursor - 1;
1060 if (i < 0)
1061 throw new NoSuchElementException();
1062 Object[] elementData = ArrayList.this.elementData;
1063 if (offset + i >= elementData.length)
1064 throw new ConcurrentModificationException();
1065 cursor = i;
1066 return (E) elementData[offset + (lastRet = i)];
1067 }
1068
1069 public int nextIndex() {
1070 return cursor;
1071 }
1072
1073 public int previousIndex() {
1074 return cursor - 1;
1075 }
1076
1077 public void remove() {
1078 if (lastRet < 0)
1079 throw new IllegalStateException();
1080 checkForComodification();
1081
1082 try {
1083 SubList.this.remove(lastRet);
1084 cursor = lastRet;
1085 lastRet = -1;
1086 expectedModCount = ArrayList.this.modCount;
1087 } catch (IndexOutOfBoundsException ex) {
1088 throw new ConcurrentModificationException();
1089 }
1090 }
1091
1092 public void set(E e) {
1093 if (lastRet < 0)
1094 throw new IllegalStateException();
1095 checkForComodification();
1096
1097 try {
1098 ArrayList.this.set(offset + lastRet, e);
1099 } catch (IndexOutOfBoundsException ex) {
1100 throw new ConcurrentModificationException();
1101 }
1102 }
1103
1104 public void add(E e) {
1105 checkForComodification();
1106
1107 try {
1108 int i = cursor;
1109 SubList.this.add(i, e);
1110 cursor = i + 1;
1111 lastRet = -1;
1112 expectedModCount = ArrayList.this.modCount;
1113 } catch (IndexOutOfBoundsException ex) {
1114 throw new ConcurrentModificationException();
1115 }
1116 }
1117
1118 final void checkForComodification() {
1119 if (expectedModCount != ArrayList.this.modCount)
1120 throw new ConcurrentModificationException();
1121 }
1122 };
1123 }
1124
1125 public List<E> subList(int fromIndex, int toIndex) {
1126 subListRangeCheck(fromIndex, toIndex, size);
1127 return new SubList(this, offset, fromIndex, toIndex);
1128 }
1129
1130 private void rangeCheck(int index) {
1131 if (index < 0 || index >= this.size)
1132 throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1133 }
1134
1135 private void rangeCheckForAdd(int index) {
1136 if (index < 0 || index > this.size)
1137 throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1138 }
1139
1140 private String outOfBoundsMsg(int index) {
1141 return "Index: "+index+", Size: "+this.size;
1142 }
1143
1144 private void checkForComodification() {
1145 if (ArrayList.this.modCount != this.modCount)
1146 throw new ConcurrentModificationException();
1147 }
1148 }
1149 }