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Comparing jsr166/src/main/java/util/ArrayList.java (file contents):
Revision 1.21 by jsr166, Sun May 28 23:36:29 2006 UTC vs.
Revision 1.29 by jsr166, Tue Jul 21 23:56:46 2009 UTC

# Line 1 | Line 1
1   /*
2 < * %W% %E%
2 > * Copyright 1997-2008 Sun Microsystems, Inc.  All Rights Reserved.
3 > * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4   *
5 < * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
6 < * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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.  Sun designates this
8 > * particular file as subject to the "Classpath" exception as provided
9 > * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 > * CA 95054 USA or visit www.sun.com if you need additional information or
23 > * have any questions.
24   */
25  
26   package java.util;
# Line 13 | Line 31 | package java.util;
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.)<p>
34 > * <tt>Vector</tt>, except that it is unsynchronized.)
35   *
36 < * The <tt>size</tt>, <tt>isEmpty</tt>, <tt>get</tt>, <tt>set</tt>,
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.<p>
41 > * to that for the <tt>LinkedList</tt> implementation.
42   *
43 < * Each <tt>ArrayList</tt> instance has a <i>capacity</i>.  The capacity is
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.<p>
48 > * time cost.
49   *
50 < * An application can increase the capacity of an <tt>ArrayList</tt> instance
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   *
# Line 48 | Line 66 | package java.util;
66   * unsynchronized access to the list:<pre>
67   *   List list = Collections.synchronizedList(new ArrayList(...));</pre>
68   *
69 < * <p>The iterators returned by this class's <tt>iterator</tt> and
70 < * <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is
71 < * structurally modified at any time after the iterator is created, in any way
72 < * except through the iterator's own <tt>remove</tt> or <tt>add</tt> methods,
73 < * the iterator will throw a {@link ConcurrentModificationException}.  Thus, in
74 < * the face of concurrent modification, the iterator fails quickly and cleanly,
75 < * rather than risking arbitrary, non-deterministic behavior at an undetermined
76 < * time in the future.<p>
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 < * Note that the fail-fast behavior of an iterator cannot be guaranteed
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 <tt>ConcurrentModificationException</tt> on a best-effort basis.
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><p>
86 > * exception for its correctness:  <i>the fail-fast behavior of iterators
87 > * should be used only to detect bugs.</i>
88   *
89 < * This class is a member of the
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 < * @version %I%, %G%
96 < * @see     Collection
97 < * @see     List
98 < * @see     LinkedList
78 < * @see     Vector
95 > * @see     Collection
96 > * @see     List
97 > * @see     LinkedList
98 > * @see     Vector
99   * @since   1.2
100   */
101  
# Line 100 | Line 120 | public class ArrayList<E> extends Abstra
120      /**
121       * Constructs an empty list with the specified initial capacity.
122       *
123 <     * @param initialCapacity the initial capacity of the list
124 <     * @throws IllegalArgumentException if the specified initial capacity
125 <     *         is negative
123 >     * @param   initialCapacity   the initial capacity of the list
124 >     * @exception IllegalArgumentException if the specified initial capacity
125 >     *            is negative
126       */
127      public ArrayList(int initialCapacity) {
128 <        super();
128 >        super();
129          if (initialCapacity < 0)
130              throw new IllegalArgumentException("Illegal Capacity: "+
131                                                 initialCapacity);
132 <        this.elementData = new Object[initialCapacity];
132 >        this.elementData = new Object[initialCapacity];
133      }
134  
135      /**
136       * Constructs an empty list with an initial capacity of ten.
137       */
138      public ArrayList() {
139 <        this(10);
139 >        this(10);
140      }
141  
142      /**
# Line 128 | Line 148 | public class ArrayList<E> extends Abstra
148       * @throws NullPointerException if the specified collection is null
149       */
150      public ArrayList(Collection<? extends E> c) {
151 <        elementData = c.toArray();
152 <        size = elementData.length;
153 <        // c.toArray might (incorrectly) not return Object[] (see 6260652)
154 <        if (elementData.getClass() != Object[].class)
155 <            elementData = Arrays.copyOf(elementData, size, Object[].class);
136 <    }
137 <
138 <    private void initFromConcurrentlyMutating(Collection<? extends E> c) {
139 <        elementData = c.toArray();
140 <        size = elementData.length;
141 <        // c.toArray might (incorrectly) not return Object[] (see 6260652)
142 <        if (elementData.getClass() != Object[].class)
143 <            elementData = Arrays.copyOf(elementData, size, Object[].class);
151 >        elementData = c.toArray();
152 >        size = elementData.length;
153 >        // c.toArray might (incorrectly) not return Object[] (see 6260652)
154 >        if (elementData.getClass() != Object[].class)
155 >            elementData = Arrays.copyOf(elementData, size, Object[].class);
156      }
157  
146    private final static Object UNALLOCATED = new Object();
147
158      /**
159       * Trims the capacity of this <tt>ArrayList</tt> instance to be the
160       * list's current size.  An application can use this operation to minimize
161       * the storage of an <tt>ArrayList</tt> instance.
162       */
163      public void trimToSize() {
164 <        modCount++;
165 <        int oldCapacity = elementData.length;
166 <        if (size < oldCapacity) {
164 >        modCount++;
165 >        int oldCapacity = elementData.length;
166 >        if (size < oldCapacity) {
167              elementData = Arrays.copyOf(elementData, size);
168 <        }
168 >        }
169      }
170  
171      /**
# Line 163 | Line 173 | public class ArrayList<E> extends Abstra
173       * necessary, to ensure that it can hold at least the number of elements
174       * specified by the minimum capacity argument.
175       *
176 <     * @param minCapacity the desired minimum capacity
176 >     * @param   minCapacity   the desired minimum capacity
177       */
178      public void ensureCapacity(int minCapacity) {
179 <        modCount++;
180 <        if (minCapacity > elementData.length)
181 <            growArray(minCapacity);
182 <    }
183 <
184 <    /**
185 <     * Increases the capacity of the array.
186 <     *
187 <     * @param minCapacity the desired minimum capacity
178 <     */
179 <    private void growArray(int minCapacity) {
180 <        if (minCapacity < 0) // overflow
181 <            throw new OutOfMemoryError();
182 <        int oldCapacity = elementData.length;
183 <        // Double size if small; else grow by 50%
184 <        int newCapacity = ((oldCapacity < 64) ?
185 <                           ((oldCapacity + 1) * 2) :
186 <                           ((oldCapacity / 2) * 3));
187 <        if (newCapacity < 0) // overflow
188 <            newCapacity = Integer.MAX_VALUE;
189 <        if (newCapacity < minCapacity)
190 <            newCapacity = minCapacity;
191 <        elementData = Arrays.copyOf(elementData, newCapacity);
179 >        modCount++;
180 >        int oldCapacity = elementData.length;
181 >        if (minCapacity > oldCapacity) {
182 >            int newCapacity = (oldCapacity * 3)/2 + 1;
183 >            if (newCapacity < minCapacity)
184 >                newCapacity = minCapacity;
185 >            // minCapacity is usually close to size, so this is a win:
186 >            elementData = Arrays.copyOf(elementData, newCapacity);
187 >        }
188      }
189  
190      /**
# Line 197 | Line 193 | public class ArrayList<E> extends Abstra
193       * @return the number of elements in this list
194       */
195      public int size() {
196 <        return size;
196 >        return size;
197      }
198  
199      /**
# Line 206 | Line 202 | public class ArrayList<E> extends Abstra
202       * @return <tt>true</tt> if this list contains no elements
203       */
204      public boolean isEmpty() {
205 <        return size == 0;
205 >        return size == 0;
206      }
207  
208      /**
# Line 219 | Line 215 | public class ArrayList<E> extends Abstra
215       * @return <tt>true</tt> if this list contains the specified element
216       */
217      public boolean contains(Object o) {
218 <        return indexOf(o) >= 0;
218 >        return indexOf(o) >= 0;
219      }
220  
221      /**
# Line 230 | Line 226 | public class ArrayList<E> extends Abstra
226       * or -1 if there is no such index.
227       */
228      public int indexOf(Object o) {
229 <        if (o == null) {
230 <            for (int i = 0; i < size; i++)
231 <                if (elementData[i]==null)
232 <                    return i;
233 <        } else {
234 <            for (int i = 0; i < size; i++)
235 <                if (o.equals(elementData[i]))
236 <                    return i;
237 <        }
238 <        return -1;
229 >        if (o == null) {
230 >            for (int i = 0; i < size; i++)
231 >                if (elementData[i]==null)
232 >                    return i;
233 >        } else {
234 >            for (int i = 0; i < size; i++)
235 >                if (o.equals(elementData[i]))
236 >                    return i;
237 >        }
238 >        return -1;
239      }
240  
241      /**
# Line 250 | Line 246 | public class ArrayList<E> extends Abstra
246       * or -1 if there is no such index.
247       */
248      public int lastIndexOf(Object o) {
249 <        if (o == null) {
250 <            for (int i = size-1; i >= 0; i--)
251 <                if (elementData[i]==null)
252 <                    return i;
253 <        } else {
254 <            for (int i = size-1; i >= 0; i--)
255 <                if (o.equals(elementData[i]))
256 <                    return i;
257 <        }
258 <        return -1;
249 >        if (o == null) {
250 >            for (int i = size-1; i >= 0; i--)
251 >                if (elementData[i]==null)
252 >                    return i;
253 >        } else {
254 >            for (int i = size-1; i >= 0; i--)
255 >                if (o.equals(elementData[i]))
256 >                    return i;
257 >        }
258 >        return -1;
259      }
260  
261      /**
# Line 269 | Line 265 | public class ArrayList<E> extends Abstra
265       * @return a clone of this <tt>ArrayList</tt> instance
266       */
267      public Object clone() {
268 <        try {
269 <            ArrayList<E> v = (ArrayList<E>) super.clone();
270 <            v.elementData = Arrays.copyOf(elementData, size);
271 <            v.modCount = 0;
272 <            return v;
273 <        } catch (CloneNotSupportedException e) {
274 <            // this shouldn't happen, since we are Cloneable
275 <            throw new InternalError();
276 <        }
268 >        try {
269 >            @SuppressWarnings("unchecked")
270 >                ArrayList<E> v = (ArrayList<E>) super.clone();
271 >            v.elementData = Arrays.copyOf(elementData, size);
272 >            v.modCount = 0;
273 >            return v;
274 >        } catch (CloneNotSupportedException e) {
275 >            // this shouldn't happen, since we are Cloneable
276 >            throw new InternalError();
277 >        }
278      }
279  
280      /**
# Line 322 | Line 319 | public class ArrayList<E> extends Abstra
319       *         this list
320       * @throws NullPointerException if the specified array is null
321       */
322 +    @SuppressWarnings("unchecked")
323      public <T> T[] toArray(T[] a) {
324          if (a.length < size)
325              // Make a new array of a's runtime type, but my contents:
326              return (T[]) Arrays.copyOf(elementData, size, a.getClass());
327 <        System.arraycopy(elementData, 0, a, 0, size);
327 >        System.arraycopy(elementData, 0, a, 0, size);
328          if (a.length > size)
329              a[size] = null;
330          return a;
# Line 334 | Line 332 | public class ArrayList<E> extends Abstra
332  
333      // Positional Access Operations
334  
335 <    /**
336 <     * Throws an appropriate exception for indexing errors.
337 <     */
340 <    private static void indexOutOfBounds(int i, int s) {
341 <        throw new IndexOutOfBoundsException("Index: " + i + ", Size: " + s);
335 >    @SuppressWarnings("unchecked")
336 >    E elementData(int index) {
337 >        return (E) elementData[index];
338      }
339  
340      /**
# Line 349 | Line 345 | public class ArrayList<E> extends Abstra
345       * @throws IndexOutOfBoundsException {@inheritDoc}
346       */
347      public E get(int index) {
348 <        if (index >= size)
349 <            indexOutOfBounds(index, size);
350 <        return (E) elementData[index];
348 >        rangeCheck(index);
349 >
350 >        return elementData(index);
351      }
352  
353      /**
# Line 364 | Line 360 | public class ArrayList<E> extends Abstra
360       * @throws IndexOutOfBoundsException {@inheritDoc}
361       */
362      public E set(int index, E element) {
363 <        if (index >= size)
364 <            indexOutOfBounds(index, size);
365 <        E oldValue = (E) elementData[index];
366 <        elementData[index] = element;
367 <        return oldValue;
363 >        rangeCheck(index);
364 >
365 >        E oldValue = elementData(index);
366 >        elementData[index] = element;
367 >        return oldValue;
368      }
369  
370      /**
# Line 378 | Line 374 | public class ArrayList<E> extends Abstra
374       * @return <tt>true</tt> (as specified by {@link Collection#add})
375       */
376      public boolean add(E e) {
377 <        modCount++;
378 <        int s = size;
379 <        if (s >= elementData.length)
384 <            growArray(s + 1);
385 <        elementData[s] = e;
386 <        size = s + 1;
387 <        return true;
377 >        ensureCapacity(size + 1);  // Increments modCount!!
378 >        elementData[size++] = e;
379 >        return true;
380      }
381  
382      /**
# Line 397 | Line 389 | public class ArrayList<E> extends Abstra
389       * @throws IndexOutOfBoundsException {@inheritDoc}
390       */
391      public void add(int index, E element) {
392 <        int s = size;
393 <        if (index > s || index < 0)
394 <            indexOutOfBounds(index, s);
395 <        modCount++;
396 <        if (s >= elementData.length)
397 <            growArray(s + 1);
398 <        System.arraycopy(elementData, index,
407 <                         elementData, index + 1, s - index);
408 <        elementData[index] = element;
409 <        size = s + 1;
392 >        rangeCheckForAdd(index);
393 >
394 >        ensureCapacity(size+1);  // Increments modCount!!
395 >        System.arraycopy(elementData, index, elementData, index + 1,
396 >                         size - index);
397 >        elementData[index] = element;
398 >        size++;
399      }
400  
401      /**
# Line 419 | Line 408 | public class ArrayList<E> extends Abstra
408       * @throws IndexOutOfBoundsException {@inheritDoc}
409       */
410      public E remove(int index) {
411 <        int s = size - 1;
412 <        if (index > s)
413 <            indexOutOfBounds(index, size);
414 <        modCount++;
415 <        E oldValue = (E) elementData[index];
416 <        int numMoved = s - index;
417 <        if (numMoved > 0)
418 <            System.arraycopy(elementData, index + 1,
419 <                             elementData, index, numMoved);
420 <        elementData[s] = null;
421 <        size = s;
422 <        return oldValue;
411 >        rangeCheck(index);
412 >
413 >        modCount++;
414 >        E oldValue = elementData(index);
415 >
416 >        int numMoved = size - index - 1;
417 >        if (numMoved > 0)
418 >            System.arraycopy(elementData, index+1, elementData, index,
419 >                             numMoved);
420 >        elementData[--size] = null; // Let gc do its work
421 >
422 >        return oldValue;
423      }
424  
425      /**
# Line 447 | Line 436 | public class ArrayList<E> extends Abstra
436       * @return <tt>true</tt> if this list contained the specified element
437       */
438      public boolean remove(Object o) {
439 <        if (o == null) {
439 >        if (o == null) {
440 >            for (int index = 0; index < size; index++)
441 >                if (elementData[index] == null) {
442 >                    fastRemove(index);
443 >                    return true;
444 >                }
445 >        } else {
446              for (int index = 0; index < size; index++)
447 <                if (elementData[index] == null) {
448 <                    fastRemove(index);
449 <                    return true;
450 <                }
456 <        } else {
457 <            for (int index = 0; index < size; index++)
458 <                if (o.equals(elementData[index])) {
459 <                    fastRemove(index);
460 <                    return true;
461 <                }
447 >                if (o.equals(elementData[index])) {
448 >                    fastRemove(index);
449 >                    return true;
450 >                }
451          }
452 <        return false;
452 >        return false;
453      }
454  
455      /*
# Line 481 | Line 470 | public class ArrayList<E> extends Abstra
470       * be empty after this call returns.
471       */
472      public void clear() {
473 <        modCount++;
473 >        modCount++;
474  
475 <        // Let gc do its work
476 <        for (int i = 0; i < size; i++)
477 <            elementData[i] = null;
475 >        // Let gc do its work
476 >        for (int i = 0; i < size; i++)
477 >            elementData[i] = null;
478  
479 <        size = 0;
479 >        size = 0;
480      }
481  
482      /**
# Line 504 | Line 493 | public class ArrayList<E> extends Abstra
493       * @throws NullPointerException if the specified collection is null
494       */
495      public boolean addAll(Collection<? extends E> c) {
496 <        Object[] a = c.toArray();
496 >        Object[] a = c.toArray();
497          int numNew = a.length;
498 <        ensureCapacity(size + numNew);  // Increments modCount
498 >        ensureCapacity(size + numNew);  // Increments modCount
499          System.arraycopy(a, 0, elementData, size, numNew);
500          size += numNew;
501 <        return numNew != 0;
501 >        return numNew != 0;
502      }
503  
504      /**
# Line 528 | Line 517 | public class ArrayList<E> extends Abstra
517       * @throws NullPointerException if the specified collection is null
518       */
519      public boolean addAll(int index, Collection<? extends E> c) {
520 <        if (index > size || index < 0)
532 <            indexOutOfBounds(index, size);
520 >        rangeCheckForAdd(index);
521  
522 <        Object[] a = c.toArray();
523 <        int numNew = a.length;
524 <        ensureCapacity(size + numNew);  // Increments modCount
525 <
526 <        int numMoved = size - index;
527 <        if (numMoved > 0)
528 <            System.arraycopy(elementData, index, elementData, index + numNew,
529 <                             numMoved);
522 >        Object[] a = c.toArray();
523 >        int numNew = a.length;
524 >        ensureCapacity(size + numNew);  // Increments modCount
525 >
526 >        int numMoved = size - index;
527 >        if (numMoved > 0)
528 >            System.arraycopy(elementData, index, elementData, index + numNew,
529 >                             numMoved);
530  
531          System.arraycopy(a, 0, elementData, index, numNew);
532 <        size += numNew;
533 <        return numNew != 0;
532 >        size += numNew;
533 >        return numNew != 0;
534      }
535  
536      /**
537       * Removes from this list all of the elements whose index is between
538 <     * <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive.
538 >     * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
539       * Shifts any succeeding elements to the left (reduces their index).
540 <     * This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements.
541 <     * (If <tt>toIndex==fromIndex</tt>, this operation has no effect.)
540 >     * This call shortens the list by {@code (toIndex - fromIndex)} elements.
541 >     * (If {@code toIndex==fromIndex}, this operation has no effect.)
542       *
543 <     * @param fromIndex index of first element to be removed
544 <     * @param toIndex index after last element to be removed
545 <     * @throws IndexOutOfBoundsException if fromIndex or toIndex out of
546 <     *              range (fromIndex &lt; 0 || fromIndex &gt;= size() || toIndex
547 <     *              &gt; size() || toIndex &lt; fromIndex)
543 >     * @throws IndexOutOfBoundsException if {@code fromIndex} or
544 >     *         {@code toIndex} is out of range
545 >     *         ({@code fromIndex < 0 ||
546 >     *          fromIndex >= size() ||
547 >     *          toIndex > size() ||
548 >     *          toIndex < fromIndex})
549       */
550      protected void removeRange(int fromIndex, int toIndex) {
551 <        modCount++;
552 <        int numMoved = size - toIndex;
551 >        modCount++;
552 >        int numMoved = size - toIndex;
553          System.arraycopy(elementData, toIndex, elementData, fromIndex,
554                           numMoved);
555  
556 <        // Let gc do its work
557 <        int newSize = size - (toIndex-fromIndex);
558 <        while (size != newSize)
559 <            elementData[--size] = null;
556 >        // Let gc do its work
557 >        int newSize = size - (toIndex-fromIndex);
558 >        while (size != newSize)
559 >            elementData[--size] = null;
560 >    }
561 >
562 >    /**
563 >     * Checks if the given index is in range.  If not, throws an appropriate
564 >     * runtime exception.  This method does *not* check if the index is
565 >     * negative: It is always used immediately prior to an array access,
566 >     * which throws an ArrayIndexOutOfBoundsException if index is negative.
567 >     */
568 >    private void rangeCheck(int index) {
569 >        if (index >= size)
570 >            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
571 >    }
572 >
573 >    /**
574 >     * A version of rangeCheck used by add and addAll.
575 >     */
576 >    private void rangeCheckForAdd(int index) {
577 >        if (index > size || index < 0)
578 >            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
579 >    }
580 >
581 >    /**
582 >     * Constructs an IndexOutOfBoundsException detail message.
583 >     * Of the many possible refactorings of the error handling code,
584 >     * this "outlining" performs best with both server and client VMs.
585 >     */
586 >    private String outOfBoundsMsg(int index) {
587 >        return "Index: "+index+", Size: "+size;
588 >    }
589 >
590 >    /**
591 >     * Removes from this list all of its elements that are contained in the
592 >     * specified collection.
593 >     *
594 >     * @param c collection containing elements to be removed from this list
595 >     * @return {@code true} if this list changed as a result of the call
596 >     * @throws ClassCastException if the class of an element of this list
597 >     *         is incompatible with the specified collection (optional)
598 >     * @throws NullPointerException if this list contains a null element and the
599 >     *         specified collection does not permit null elements (optional),
600 >     *         or if the specified collection is null
601 >     * @see Collection#contains(Object)
602 >     */
603 >    public boolean removeAll(Collection<?> c) {
604 >        return batchRemove(c, false);
605 >    }
606 >
607 >    /**
608 >     * Retains only the elements in this list that are contained in the
609 >     * specified collection.  In other words, removes from this list all
610 >     * of its elements that are not contained in the specified collection.
611 >     *
612 >     * @param c collection containing elements to be retained in this list
613 >     * @return {@code true} if this list changed as a result of the call
614 >     * @throws ClassCastException if the class of an element of this list
615 >     *         is incompatible with the specified collection (optional)
616 >     * @throws NullPointerException if this list contains a null element and the
617 >     *         specified collection does not permit null elements (optional),
618 >     *         or if the specified collection is null
619 >     * @see Collection#contains(Object)
620 >     */
621 >    public boolean retainAll(Collection<?> c) {
622 >        return batchRemove(c, true);
623 >    }
624 >
625 >    private boolean batchRemove(Collection<?> c, boolean complement) {
626 >        final Object[] elementData = this.elementData;
627 >        int r = 0, w = 0;
628 >        boolean modified = false;
629 >        try {
630 >            for (; r < size; r++)
631 >                if (c.contains(elementData[r]) == complement)
632 >                    elementData[w++] = elementData[r];
633 >        } finally {
634 >            // Preserve behavioral compatibility with AbstractCollection,
635 >            // even if c.contains() throws.
636 >            if (r != size) {
637 >                System.arraycopy(elementData, r,
638 >                                 elementData, w,
639 >                                 size - r);
640 >                w += size - r;
641 >            }
642 >            if (w != size) {
643 >                for (int i = w; i < size; i++)
644 >                    elementData[i] = null;
645 >                modCount += size - w;
646 >                size = w;
647 >                modified = true;
648 >            }
649 >        }
650 >        return modified;
651      }
652  
653      /**
# Line 580 | Line 660 | public class ArrayList<E> extends Abstra
660       */
661      private void writeObject(java.io.ObjectOutputStream s)
662          throws java.io.IOException{
663 <        // Write out element count, and any hidden stuff
664 <        int expectedModCount = modCount;
665 <        s.defaultWriteObject();
663 >        // Write out element count, and any hidden stuff
664 >        int expectedModCount = modCount;
665 >        s.defaultWriteObject();
666  
667          // Write out array length
668          s.writeInt(elementData.length);
669  
670 <        // Write out all elements in the proper order.
671 <        for (int i=0; i<size; i++)
670 >        // Write out all elements in the proper order.
671 >        for (int i=0; i<size; i++)
672              s.writeObject(elementData[i]);
673  
674 <        if (expectedModCount != modCount) {
674 >        if (modCount != expectedModCount) {
675              throw new ConcurrentModificationException();
676          }
677  
# Line 603 | Line 683 | public class ArrayList<E> extends Abstra
683       */
684      private void readObject(java.io.ObjectInputStream s)
685          throws java.io.IOException, ClassNotFoundException {
686 <        // Read in size, and any hidden stuff
687 <        s.defaultReadObject();
686 >        // Read in size, and any hidden stuff
687 >        s.defaultReadObject();
688  
689          // Read in array length and allocate array
690          int arrayLength = s.readInt();
691          Object[] a = elementData = new Object[arrayLength];
692  
693 <        // Read in all elements in the proper order.
694 <        for (int i=0; i<size; i++)
693 >        // Read in all elements in the proper order.
694 >        for (int i=0; i<size; i++)
695              a[i] = s.readObject();
696      }
697 +
698 +    /**
699 +     * Returns a list iterator over the elements in this list (in proper
700 +     * sequence), starting at the specified position in the list.
701 +     * The specified index indicates the first element that would be
702 +     * returned by an initial call to {@link ListIterator#next next}.
703 +     * An initial call to {@link ListIterator#previous previous} would
704 +     * return the element with the specified index minus one.
705 +     *
706 +     * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
707 +     *
708 +     * @throws IndexOutOfBoundsException {@inheritDoc}
709 +     */
710 +    public ListIterator<E> listIterator(int index) {
711 +        if (index < 0 || index > size)
712 +            throw new IndexOutOfBoundsException("Index: "+index);
713 +        return new ListItr(index);
714 +    }
715 +
716 +    /**
717 +     * Returns a list iterator over the elements in this list (in proper
718 +     * sequence).
719 +     *
720 +     * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
721 +     *
722 +     * @see #listIterator(int)
723 +     */
724 +    public ListIterator<E> listIterator() {
725 +        return new ListItr(0);
726 +    }
727 +
728 +    /**
729 +     * Returns an iterator over the elements in this list in proper sequence.
730 +     *
731 +     * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
732 +     *
733 +     * @return an iterator over the elements in this list in proper sequence
734 +     */
735 +    public Iterator<E> iterator() {
736 +        return new Itr();
737 +    }
738 +
739 +    /**
740 +     * An optimized version of AbstractList.Itr
741 +     */
742 +    private class Itr implements Iterator<E> {
743 +        int cursor;       // index of next element to return
744 +        int lastRet = -1; // index of last element returned; -1 if no such
745 +        int expectedModCount = modCount;
746 +
747 +        public boolean hasNext() {
748 +            return cursor != size;
749 +        }
750 +
751 +        @SuppressWarnings("unchecked")
752 +        public E next() {
753 +            checkForComodification();
754 +            int i = cursor;
755 +            if (i >= size)
756 +                throw new NoSuchElementException();
757 +            Object[] elementData = ArrayList.this.elementData;
758 +            if (i >= elementData.length)
759 +                throw new ConcurrentModificationException();
760 +            cursor = i + 1;
761 +            return (E) elementData[lastRet = i];
762 +        }
763 +
764 +        public void remove() {
765 +            if (lastRet < 0)
766 +                throw new IllegalStateException();
767 +            checkForComodification();
768 +
769 +            try {
770 +                ArrayList.this.remove(lastRet);
771 +                cursor = lastRet;
772 +                lastRet = -1;
773 +                expectedModCount = modCount;
774 +            } catch (IndexOutOfBoundsException ex) {
775 +                throw new ConcurrentModificationException();
776 +            }
777 +        }
778 +
779 +        final void checkForComodification() {
780 +            if (modCount != expectedModCount)
781 +                throw new ConcurrentModificationException();
782 +        }
783 +    }
784 +
785 +    /**
786 +     * An optimized version of AbstractList.ListItr
787 +     */
788 +    private class ListItr extends Itr implements ListIterator<E> {
789 +        ListItr(int index) {
790 +            super();
791 +            cursor = index;
792 +        }
793 +
794 +        public boolean hasPrevious() {
795 +            return cursor != 0;
796 +        }
797 +
798 +        public int nextIndex() {
799 +            return cursor;
800 +        }
801 +
802 +        public int previousIndex() {
803 +            return cursor - 1;
804 +        }
805 +
806 +        @SuppressWarnings("unchecked")
807 +        public E previous() {
808 +            checkForComodification();
809 +            int i = cursor - 1;
810 +            if (i < 0)
811 +                throw new NoSuchElementException();
812 +            Object[] elementData = ArrayList.this.elementData;
813 +            if (i >= elementData.length)
814 +                throw new ConcurrentModificationException();
815 +            cursor = i;
816 +            return (E) elementData[lastRet = i];
817 +        }
818 +
819 +        public void set(E e) {
820 +            if (lastRet < 0)
821 +                throw new IllegalStateException();
822 +            checkForComodification();
823 +
824 +            try {
825 +                ArrayList.this.set(lastRet, e);
826 +            } catch (IndexOutOfBoundsException ex) {
827 +                throw new ConcurrentModificationException();
828 +            }
829 +        }
830 +
831 +        public void add(E e) {
832 +            checkForComodification();
833 +
834 +            try {
835 +                int i = cursor;
836 +                ArrayList.this.add(i, e);
837 +                cursor = i + 1;
838 +                lastRet = -1;
839 +                expectedModCount = modCount;
840 +            } catch (IndexOutOfBoundsException ex) {
841 +                throw new ConcurrentModificationException();
842 +            }
843 +        }
844 +    }
845 +
846 +    /**
847 +     * Returns a view of the portion of this list between the specified
848 +     * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.  (If
849 +     * {@code fromIndex} and {@code toIndex} are equal, the returned list is
850 +     * empty.)  The returned list is backed by this list, so non-structural
851 +     * changes in the returned list are reflected in this list, and vice-versa.
852 +     * The returned list supports all of the optional list operations.
853 +     *
854 +     * <p>This method eliminates the need for explicit range operations (of
855 +     * the sort that commonly exist for arrays).  Any operation that expects
856 +     * a list can be used as a range operation by passing a subList view
857 +     * instead of a whole list.  For example, the following idiom
858 +     * removes a range of elements from a list:
859 +     * <pre>
860 +     *      list.subList(from, to).clear();
861 +     * </pre>
862 +     * Similar idioms may be constructed for {@link #indexOf(Object)} and
863 +     * {@link #lastIndexOf(Object)}, and all of the algorithms in the
864 +     * {@link Collections} class can be applied to a subList.
865 +     *
866 +     * <p>The semantics of the list returned by this method become undefined if
867 +     * the backing list (i.e., this list) is <i>structurally modified</i> in
868 +     * any way other than via the returned list.  (Structural modifications are
869 +     * those that change the size of this list, or otherwise perturb it in such
870 +     * a fashion that iterations in progress may yield incorrect results.)
871 +     *
872 +     * @throws IndexOutOfBoundsException {@inheritDoc}
873 +     * @throws IllegalArgumentException {@inheritDoc}
874 +     */
875 +    public List<E> subList(int fromIndex, int toIndex) {
876 +        subListRangeCheck(fromIndex, toIndex, size);
877 +        return new SubList(this, 0, fromIndex, toIndex);
878 +    }
879 +
880 +    static void subListRangeCheck(int fromIndex, int toIndex, int size) {
881 +        if (fromIndex < 0)
882 +            throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
883 +        if (toIndex > size)
884 +            throw new IndexOutOfBoundsException("toIndex = " + toIndex);
885 +        if (fromIndex > toIndex)
886 +            throw new IllegalArgumentException("fromIndex(" + fromIndex +
887 +                                               ") > toIndex(" + toIndex + ")");
888 +    }
889 +
890 +    private class SubList extends AbstractList<E> implements RandomAccess {
891 +        private final AbstractList<E> parent;
892 +        private final int parentOffset;
893 +        private final int offset;
894 +        int size;
895 +
896 +        SubList(AbstractList<E> parent,
897 +                int offset, int fromIndex, int toIndex) {
898 +            this.parent = parent;
899 +            this.parentOffset = fromIndex;
900 +            this.offset = offset + fromIndex;
901 +            this.size = toIndex - fromIndex;
902 +            this.modCount = ArrayList.this.modCount;
903 +        }
904 +
905 +        public E set(int index, E e) {
906 +            rangeCheck(index);
907 +            checkForComodification();
908 +            E oldValue = ArrayList.this.elementData(offset + index);
909 +            ArrayList.this.elementData[offset + index] = e;
910 +            return oldValue;
911 +        }
912 +
913 +        public E get(int index) {
914 +            rangeCheck(index);
915 +            checkForComodification();
916 +            return ArrayList.this.elementData(offset + index);
917 +        }
918 +
919 +        public int size() {
920 +            checkForComodification();
921 +            return this.size;
922 +        }
923 +
924 +        public void add(int index, E e) {
925 +            rangeCheckForAdd(index);
926 +            checkForComodification();
927 +            parent.add(parentOffset + index, e);
928 +            this.modCount = parent.modCount;
929 +            this.size++;
930 +        }
931 +
932 +        public E remove(int index) {
933 +            rangeCheck(index);
934 +            checkForComodification();
935 +            E result = parent.remove(parentOffset + index);
936 +            this.modCount = parent.modCount;
937 +            this.size--;
938 +            return result;
939 +        }
940 +
941 +        protected void removeRange(int fromIndex, int toIndex) {
942 +            checkForComodification();
943 +            parent.removeRange(parentOffset + fromIndex,
944 +                               parentOffset + toIndex);
945 +            this.modCount = parent.modCount;
946 +            this.size -= toIndex - fromIndex;
947 +        }
948 +
949 +        public boolean addAll(Collection<? extends E> c) {
950 +            return addAll(this.size, c);
951 +        }
952 +
953 +        public boolean addAll(int index, Collection<? extends E> c) {
954 +            rangeCheckForAdd(index);
955 +            int cSize = c.size();
956 +            if (cSize==0)
957 +                return false;
958 +
959 +            checkForComodification();
960 +            parent.addAll(parentOffset + index, c);
961 +            this.modCount = parent.modCount;
962 +            this.size += cSize;
963 +            return true;
964 +        }
965 +
966 +        public Iterator<E> iterator() {
967 +            return listIterator();
968 +        }
969 +
970 +        public ListIterator<E> listIterator(final int index) {
971 +            checkForComodification();
972 +            rangeCheckForAdd(index);
973 +            final int offset = this.offset;
974 +
975 +            return new ListIterator<E>() {
976 +                int cursor = index;
977 +                int lastRet = -1;
978 +                int expectedModCount = ArrayList.this.modCount;
979 +
980 +                public boolean hasNext() {
981 +                    return cursor != SubList.this.size;
982 +                }
983 +
984 +                @SuppressWarnings("unchecked")
985 +                public E next() {
986 +                    checkForComodification();
987 +                    int i = cursor;
988 +                    if (i >= SubList.this.size)
989 +                        throw new NoSuchElementException();
990 +                    Object[] elementData = ArrayList.this.elementData;
991 +                    if (offset + i >= elementData.length)
992 +                        throw new ConcurrentModificationException();
993 +                    cursor = i + 1;
994 +                    return (E) elementData[offset + (lastRet = i)];
995 +                }
996 +
997 +                public boolean hasPrevious() {
998 +                    return cursor != 0;
999 +                }
1000 +
1001 +                @SuppressWarnings("unchecked")
1002 +                public E previous() {
1003 +                    checkForComodification();
1004 +                    int i = cursor - 1;
1005 +                    if (i < 0)
1006 +                        throw new NoSuchElementException();
1007 +                    Object[] elementData = ArrayList.this.elementData;
1008 +                    if (offset + i >= elementData.length)
1009 +                        throw new ConcurrentModificationException();
1010 +                    cursor = i;
1011 +                    return (E) elementData[offset + (lastRet = i)];
1012 +                }
1013 +
1014 +                public int nextIndex() {
1015 +                    return cursor;
1016 +                }
1017 +
1018 +                public int previousIndex() {
1019 +                    return cursor - 1;
1020 +                }
1021 +
1022 +                public void remove() {
1023 +                    if (lastRet < 0)
1024 +                        throw new IllegalStateException();
1025 +                    checkForComodification();
1026 +
1027 +                    try {
1028 +                        SubList.this.remove(lastRet);
1029 +                        cursor = lastRet;
1030 +                        lastRet = -1;
1031 +                        expectedModCount = ArrayList.this.modCount;
1032 +                    } catch (IndexOutOfBoundsException ex) {
1033 +                        throw new ConcurrentModificationException();
1034 +                    }
1035 +                }
1036 +
1037 +                public void set(E e) {
1038 +                    if (lastRet < 0)
1039 +                        throw new IllegalStateException();
1040 +                    checkForComodification();
1041 +
1042 +                    try {
1043 +                        ArrayList.this.set(offset + lastRet, e);
1044 +                    } catch (IndexOutOfBoundsException ex) {
1045 +                        throw new ConcurrentModificationException();
1046 +                    }
1047 +                }
1048 +
1049 +                public void add(E e) {
1050 +                    checkForComodification();
1051 +
1052 +                    try {
1053 +                        int i = cursor;
1054 +                        SubList.this.add(i, e);
1055 +                        cursor = i + 1;
1056 +                        lastRet = -1;
1057 +                        expectedModCount = ArrayList.this.modCount;
1058 +                    } catch (IndexOutOfBoundsException ex) {
1059 +                        throw new ConcurrentModificationException();
1060 +                    }
1061 +                }
1062 +
1063 +                final void checkForComodification() {
1064 +                    if (expectedModCount != ArrayList.this.modCount)
1065 +                        throw new ConcurrentModificationException();
1066 +                }
1067 +            };
1068 +        }
1069 +
1070 +        public List<E> subList(int fromIndex, int toIndex) {
1071 +            subListRangeCheck(fromIndex, toIndex, size);
1072 +            return new SubList(this, offset, fromIndex, toIndex);
1073 +        }
1074 +
1075 +        private void rangeCheck(int index) {
1076 +            if (index < 0 || index >= this.size)
1077 +                throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1078 +        }
1079 +
1080 +        private void rangeCheckForAdd(int index) {
1081 +            if (index < 0 || index > this.size)
1082 +                throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1083 +        }
1084 +
1085 +        private String outOfBoundsMsg(int index) {
1086 +            return "Index: "+index+", Size: "+this.size;
1087 +        }
1088 +
1089 +        private void checkForComodification() {
1090 +            if (ArrayList.this.modCount != this.modCount)
1091 +                throw new ConcurrentModificationException();
1092 +        }
1093 +    }
1094   }

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