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Comparing jsr166/src/main/java/util/ArrayList.java (file contents):
Revision 1.7 by dl, Sat Nov 26 17:35:19 2005 UTC vs.
Revision 1.28 by jsr166, Mon May 19 00:32:45 2008 UTC

# Line 1 | Line 1
1   /*
2 < * %W% %E%
2 > * Copyright 1997-2007 Sun Microsystems, Inc.  All Rights Reserved.
3 > * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4   *
5 < * Copyright 2005 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;
9 import java.util.*; // for javadoc (till 6280605 is fixed)
27  
28   /**
29   * Resizable-array implementation of the <tt>List</tt> interface.  Implements
# Line 14 | Line 31 | import java.util.*; // for javadoc (till
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 49 | Line 66 | import java.util.*; // for javadoc (till
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
90 < * <a href="{@docRoot}/../guide/collections/index.html">
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
79 < * @see     Vector
95 > * @see     Collection
96 > * @see     List
97 > * @see     LinkedList
98 > * @see     Vector
99   * @since   1.2
100   */
101  
# Line 101 | 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      /**
143       * Constructs a list containing the elements of the specified
144       * collection, in the order they are returned by the collection's
145 <     * iterator.  The <tt>ArrayList</tt> instance has an initial capacity of
127 <     * 110% the size of the specified collection.
145 >     * iterator.
146       *
147       * @param c the collection whose elements are to be placed into this list
148       * @throws NullPointerException if the specified collection is null
149       */
150      public ArrayList(Collection<? extends E> c) {
151 <        int size = c.size();
152 <        // 10% for growth
153 <        int cap = ((size/10)+1)*11;
154 <        if (cap > 0) {
155 <            Object[] a = new Object[cap];
138 <            a[size] = a[size+1] = UNALLOCATED;
139 <            Object[] b = c.toArray(a);
140 <            if (b[size] == null && b[size+1] == UNALLOCATED) {
141 <                b[size+1] = null;
142 <                elementData = b;
143 <                this.size = size;
144 <                return;
145 <            }
146 <        }
147 <        initFromConcurrentlyMutating(c);
148 <    }
149 <
150 <    private void initFromConcurrentlyMutating(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);
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  
158    private final static Object UNALLOCATED = new Object();
159
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 175 | 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
188 <     */
191 <    private void growArray(int minCapacity) {
192 <        if (minCapacity < 0) throw new OutOfMemoryError(); // int overflow
193 <        int oldCapacity = elementData.length;
194 <        // Double size if small; else grow by 50%
195 <        int newCapacity = ((oldCapacity < 64)?
196 <                           (oldCapacity * 2):
197 <                           ((oldCapacity * 3)/2));
198 <        if (newCapacity < minCapacity)
199 <            newCapacity = minCapacity;
200 <        elementData = Arrays.copyOf(elementData, newCapacity);
179 >        modCount++;
180 >        int oldCapacity = elementData.length;
181 >        if (minCapacity > oldCapacity) {
182 >            Object oldData[] = elementData;
183 >            int newCapacity = (oldCapacity * 3)/2 + 1;
184 >            if (newCapacity < minCapacity)
185 >                newCapacity = minCapacity;
186 >            // minCapacity is usually close to size, so this is a win:
187 >            elementData = Arrays.copyOf(elementData, newCapacity);
188 >        }
189      }
190  
191      /**
# Line 206 | Line 194 | public class ArrayList<E> extends Abstra
194       * @return the number of elements in this list
195       */
196      public int size() {
197 <        return size;
197 >        return size;
198      }
199  
200      /**
# Line 215 | Line 203 | public class ArrayList<E> extends Abstra
203       * @return <tt>true</tt> if this list contains no elements
204       */
205      public boolean isEmpty() {
206 <        return size == 0;
206 >        return size == 0;
207      }
208  
209      /**
# Line 228 | Line 216 | public class ArrayList<E> extends Abstra
216       * @return <tt>true</tt> if this list contains the specified element
217       */
218      public boolean contains(Object o) {
219 <        return indexOf(o) >= 0;
219 >        return indexOf(o) >= 0;
220      }
221  
222      /**
# Line 239 | Line 227 | public class ArrayList<E> extends Abstra
227       * or -1 if there is no such index.
228       */
229      public int indexOf(Object o) {
230 <        if (o == null) {
231 <            for (int i = 0; i < size; i++)
232 <                if (elementData[i]==null)
233 <                    return i;
234 <        } else {
235 <            for (int i = 0; i < size; i++)
236 <                if (o.equals(elementData[i]))
237 <                    return i;
238 <        }
239 <        return -1;
230 >        if (o == null) {
231 >            for (int i = 0; i < size; i++)
232 >                if (elementData[i]==null)
233 >                    return i;
234 >        } else {
235 >            for (int i = 0; i < size; i++)
236 >                if (o.equals(elementData[i]))
237 >                    return i;
238 >        }
239 >        return -1;
240      }
241  
242      /**
# Line 259 | Line 247 | public class ArrayList<E> extends Abstra
247       * or -1 if there is no such index.
248       */
249      public int lastIndexOf(Object o) {
250 <        if (o == null) {
251 <            for (int i = size-1; i >= 0; i--)
252 <                if (elementData[i]==null)
253 <                    return i;
254 <        } else {
255 <            for (int i = size-1; i >= 0; i--)
256 <                if (o.equals(elementData[i]))
257 <                    return i;
258 <        }
259 <        return -1;
250 >        if (o == null) {
251 >            for (int i = size-1; i >= 0; i--)
252 >                if (elementData[i]==null)
253 >                    return i;
254 >        } else {
255 >            for (int i = size-1; i >= 0; i--)
256 >                if (o.equals(elementData[i]))
257 >                    return i;
258 >        }
259 >        return -1;
260      }
261  
262      /**
# Line 278 | Line 266 | public class ArrayList<E> extends Abstra
266       * @return a clone of this <tt>ArrayList</tt> instance
267       */
268      public Object clone() {
269 <        try {
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 <        }
269 >        try {
270 >            @SuppressWarnings("unchecked")
271 >                ArrayList<E> v = (ArrayList<E>) super.clone();
272 >            v.elementData = Arrays.copyOf(elementData, size);
273 >            v.modCount = 0;
274 >            return v;
275 >        } catch (CloneNotSupportedException e) {
276 >            // this shouldn't happen, since we are Cloneable
277 >            throw new InternalError();
278 >        }
279      }
280  
281      /**
# Line 331 | Line 320 | public class ArrayList<E> extends Abstra
320       *         this list
321       * @throws NullPointerException if the specified array is null
322       */
323 +    @SuppressWarnings("unchecked")
324      public <T> T[] toArray(T[] a) {
325          if (a.length < size)
326              // Make a new array of a's runtime type, but my contents:
327              return (T[]) Arrays.copyOf(elementData, size, a.getClass());
328 <        System.arraycopy(elementData, 0, a, 0, size);
328 >        System.arraycopy(elementData, 0, a, 0, size);
329          if (a.length > size)
330              a[size] = null;
331          return a;
# Line 343 | Line 333 | public class ArrayList<E> extends Abstra
333  
334      // Positional Access Operations
335  
336 <    /**
337 <     * Throws an appropriate exception for indexing errors.
338 <     */
349 <    private static void rangeException(int i, int s) {
350 <        throw new IndexOutOfBoundsException("Index: " + i + ", Size: " + s);
336 >    @SuppressWarnings("unchecked")
337 >    E elementData(int index) {
338 >        return (E) elementData[index];
339      }
340  
341      /**
# Line 358 | Line 346 | public class ArrayList<E> extends Abstra
346       * @throws IndexOutOfBoundsException {@inheritDoc}
347       */
348      public E get(int index) {
349 <        if (index >= size)
350 <            rangeException(index, size);
351 <        return (E)elementData[index];
349 >        rangeCheck(index);
350 >
351 >        return elementData(index);
352      }
353  
354      /**
# Line 373 | Line 361 | public class ArrayList<E> extends Abstra
361       * @throws IndexOutOfBoundsException {@inheritDoc}
362       */
363      public E set(int index, E element) {
364 <        if (index >= size)
377 <            rangeException(index, size);
364 >        rangeCheck(index);
365  
366 <        E oldValue = (E) elementData[index];
367 <        elementData[index] = element;
368 <        return oldValue;
366 >        E oldValue = elementData(index);
367 >        elementData[index] = element;
368 >        return oldValue;
369      }
370  
371      /**
# Line 388 | Line 375 | public class ArrayList<E> extends Abstra
375       * @return <tt>true</tt> (as specified by {@link Collection#add})
376       */
377      public boolean add(E e) {
378 <        ++modCount;
379 <        int s = size;
380 <        if (s >= elementData.length)
394 <            growArray(s + 1);
395 <        elementData[s] = e;
396 <        size = s + 1;
397 <        return true;
378 >        ensureCapacity(size + 1);  // Increments modCount!!
379 >        elementData[size++] = e;
380 >        return true;
381      }
382  
383      /**
# Line 407 | Line 390 | public class ArrayList<E> extends Abstra
390       * @throws IndexOutOfBoundsException {@inheritDoc}
391       */
392      public void add(int index, E element) {
393 <        int s = size;
394 <        if (index > s || index < 0)
395 <            rangeException(index, s);
396 <        ++modCount;
397 <        if (s >= elementData.length)
398 <            growArray(s + 1);
399 <        System.arraycopy(elementData, index,
417 <                         elementData, index + 1, s - index);
418 <        elementData[index] = element;
419 <        size = s + 1;
393 >        rangeCheckForAdd(index);
394 >
395 >        ensureCapacity(size+1);  // Increments modCount!!
396 >        System.arraycopy(elementData, index, elementData, index + 1,
397 >                         size - index);
398 >        elementData[index] = element;
399 >        size++;
400      }
401  
402      /**
# Line 429 | Line 409 | public class ArrayList<E> extends Abstra
409       * @throws IndexOutOfBoundsException {@inheritDoc}
410       */
411      public E remove(int index) {
412 <        int s = size - 1;
413 <        if (index < 0 || index > s)
414 <            rangeException(index, size);
415 <        modCount++;
416 <        E oldValue = (E)elementData[index];
417 <        int numMoved = s - index;
418 <        if (numMoved > 0)
419 <            System.arraycopy(elementData, index + 1,
420 <                             elementData, index, numMoved);
421 <        elementData[s] = null; // forget removed element
422 <        size = s;
423 <        return oldValue;
412 >        rangeCheck(index);
413 >
414 >        modCount++;
415 >        E oldValue = elementData(index);
416 >
417 >        int numMoved = size - index - 1;
418 >        if (numMoved > 0)
419 >            System.arraycopy(elementData, index+1, elementData, index,
420 >                             numMoved);
421 >        elementData[--size] = null; // Let gc do its work
422 >
423 >        return oldValue;
424      }
425  
426      /**
# Line 457 | Line 437 | public class ArrayList<E> extends Abstra
437       * @return <tt>true</tt> if this list contained the specified element
438       */
439      public boolean remove(Object o) {
440 <        if (o == null) {
440 >        if (o == null) {
441 >            for (int index = 0; index < size; index++)
442 >                if (elementData[index] == null) {
443 >                    fastRemove(index);
444 >                    return true;
445 >                }
446 >        } else {
447              for (int index = 0; index < size; index++)
448 <                if (elementData[index] == null) {
449 <                    fastRemove(index);
450 <                    return true;
451 <                }
466 <        } else {
467 <            for (int index = 0; index < size; index++)
468 <                if (o.equals(elementData[index])) {
469 <                    fastRemove(index);
470 <                    return true;
471 <                }
448 >                if (o.equals(elementData[index])) {
449 >                    fastRemove(index);
450 >                    return true;
451 >                }
452          }
453 <        return false;
453 >        return false;
454      }
455  
456      /*
# Line 491 | Line 471 | public class ArrayList<E> extends Abstra
471       * be empty after this call returns.
472       */
473      public void clear() {
474 <        modCount++;
474 >        modCount++;
475  
476 <        // Let gc do its work
477 <        for (int i = 0; i < size; i++)
478 <            elementData[i] = null;
476 >        // Let gc do its work
477 >        for (int i = 0; i < size; i++)
478 >            elementData[i] = null;
479  
480 <        size = 0;
480 >        size = 0;
481      }
482  
483      /**
# Line 514 | Line 494 | public class ArrayList<E> extends Abstra
494       * @throws NullPointerException if the specified collection is null
495       */
496      public boolean addAll(Collection<? extends E> c) {
497 <        Object[] a = c.toArray();
497 >        Object[] a = c.toArray();
498          int numNew = a.length;
499 <        ensureCapacity(size + numNew);  // Increments modCount
499 >        ensureCapacity(size + numNew);  // Increments modCount
500          System.arraycopy(a, 0, elementData, size, numNew);
501          size += numNew;
502 <        return numNew != 0;
502 >        return numNew != 0;
503      }
504  
505      /**
# Line 538 | Line 518 | public class ArrayList<E> extends Abstra
518       * @throws NullPointerException if the specified collection is null
519       */
520      public boolean addAll(int index, Collection<? extends E> c) {
521 <        if (index > size || index < 0)
522 <            throw new IndexOutOfBoundsException(
523 <                "Index: " + index + ", Size: " + size);
524 <
525 <        Object[] a = c.toArray();
526 <        int numNew = a.length;
527 <        ensureCapacity(size + numNew);  // Increments modCount
528 <
529 <        int numMoved = size - index;
530 <        if (numMoved > 0)
551 <            System.arraycopy(elementData, index, elementData, index + numNew,
552 <                             numMoved);
521 >        rangeCheckForAdd(index);
522 >
523 >        Object[] a = c.toArray();
524 >        int numNew = a.length;
525 >        ensureCapacity(size + numNew);  // Increments modCount
526 >
527 >        int numMoved = size - index;
528 >        if (numMoved > 0)
529 >            System.arraycopy(elementData, index, elementData, index + numNew,
530 >                             numMoved);
531  
532          System.arraycopy(a, 0, elementData, index, numNew);
533 <        size += numNew;
534 <        return numNew != 0;
533 >        size += numNew;
534 >        return numNew != 0;
535      }
536  
537      /**
538       * Removes from this list all of the elements whose index is between
539 <     * <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive.
539 >     * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
540       * Shifts any succeeding elements to the left (reduces their index).
541 <     * This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements.
542 <     * (If <tt>toIndex==fromIndex</tt>, this operation has no effect.)
541 >     * This call shortens the list by {@code (toIndex - fromIndex)} elements.
542 >     * (If {@code toIndex==fromIndex}, this operation has no effect.)
543       *
544 <     * @param fromIndex index of first element to be removed
545 <     * @param toIndex index after last element to be removed
546 <     * @throws IndexOutOfBoundsException if fromIndex or toIndex out of
547 <     *              range (fromIndex &lt; 0 || fromIndex &gt;= size() || toIndex
548 <     *              &gt; size() || toIndex &lt; fromIndex)
544 >     * @throws IndexOutOfBoundsException if {@code fromIndex} or
545 >     *         {@code toIndex} is out of range
546 >     *         ({@code fromIndex < 0 ||
547 >     *          fromIndex >= size() ||
548 >     *          toIndex > size() ||
549 >     *          toIndex < fromIndex})
550       */
551      protected void removeRange(int fromIndex, int toIndex) {
552 <        modCount++;
553 <        int numMoved = size - toIndex;
552 >        modCount++;
553 >        int numMoved = size - toIndex;
554          System.arraycopy(elementData, toIndex, elementData, fromIndex,
555                           numMoved);
556  
557 <        // Let gc do its work
558 <        int newSize = size - (toIndex-fromIndex);
559 <        while (size != newSize)
560 <            elementData[--size] = null;
557 >        // Let gc do its work
558 >        int newSize = size - (toIndex-fromIndex);
559 >        while (size != newSize)
560 >            elementData[--size] = null;
561 >    }
562 >
563 >    /**
564 >     * Checks if the given index is in range.  If not, throws an appropriate
565 >     * runtime exception.  This method does *not* check if the index is
566 >     * negative: It is always used immediately prior to an array access,
567 >     * which throws an ArrayIndexOutOfBoundsException if index is negative.
568 >     */
569 >    private void rangeCheck(int index) {
570 >        if (index >= size)
571 >            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
572 >    }
573 >
574 >    /**
575 >     * A version of rangeCheck used by add and addAll.
576 >     */
577 >    private void rangeCheckForAdd(int index) {
578 >        if (index > size || index < 0)
579 >            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
580 >    }
581 >
582 >    /**
583 >     * Constructs an IndexOutOfBoundsException detail message.
584 >     * Of the many possible refactorings of the error handling code,
585 >     * this "outlining" performs best with both server and client VMs.
586 >     */
587 >    private String outOfBoundsMsg(int index) {
588 >        return "Index: "+index+", Size: "+size;
589 >    }
590 >
591 >    /**
592 >     * Removes from this list all of its elements that are contained in the
593 >     * specified collection.
594 >     *
595 >     * @param c collection containing elements to be removed from this list
596 >     * @return {@code true} if this list changed as a result of the call
597 >     * @throws ClassCastException if the class of an element of this list
598 >     *         is incompatible with the specified collection (optional)
599 >     * @throws NullPointerException if this list contains a null element and the
600 >     *         specified collection does not permit null elements (optional),
601 >     *         or if the specified collection is null
602 >     * @see Collection#contains(Object)
603 >     */
604 >    public boolean removeAll(Collection<?> c) {
605 >        return batchRemove(c, false);
606 >    }
607 >
608 >    /**
609 >     * Retains only the elements in this list that are contained in the
610 >     * specified collection.  In other words, removes from this list all
611 >     * of its elements that are not contained in the specified collection.
612 >     *
613 >     * @param c collection containing elements to be retained in this list
614 >     * @return {@code true} if this list changed as a result of the call
615 >     * @throws ClassCastException if the class of an element of this list
616 >     *         is incompatible with the specified collection (optional)
617 >     * @throws NullPointerException if this list contains a null element and the
618 >     *         specified collection does not permit null elements (optional),
619 >     *         or if the specified collection is null
620 >     * @see Collection#contains(Object)
621 >     */
622 >    public boolean retainAll(Collection<?> c) {
623 >        return batchRemove(c, true);
624 >    }
625 >
626 >    private boolean batchRemove(Collection<?> c, boolean complement) {
627 >        final Object[] elementData = this.elementData;
628 >        int r = 0, w = 0;
629 >        boolean modified = false;
630 >        try {
631 >            for (; r < size; r++)
632 >                if (c.contains(elementData[r]) == complement)
633 >                    elementData[w++] = elementData[r];
634 >        } finally {
635 >            // Preserve behavioral compatibility with AbstractCollection,
636 >            // even if c.contains() throws.
637 >            if (r != size) {
638 >                System.arraycopy(elementData, r,
639 >                                 elementData, w,
640 >                                 size - r);
641 >                w += size - r;
642 >            }
643 >            if (w != size) {
644 >                for (int i = w; i < size; i++)
645 >                    elementData[i] = null;
646 >                modCount += size - w;
647 >                size = w;
648 >                modified = true;
649 >            }
650 >        }
651 >        return modified;
652      }
653  
654      /**
# Line 591 | Line 661 | public class ArrayList<E> extends Abstra
661       */
662      private void writeObject(java.io.ObjectOutputStream s)
663          throws java.io.IOException{
664 <        // Write out element count, and any hidden stuff
665 <        int expectedModCount = modCount;
666 <        s.defaultWriteObject();
664 >        // Write out element count, and any hidden stuff
665 >        int expectedModCount = modCount;
666 >        s.defaultWriteObject();
667  
668          // Write out array length
669          s.writeInt(elementData.length);
670  
671 <        // Write out all elements in the proper order.
672 <        for (int i=0; i<size; i++)
671 >        // Write out all elements in the proper order.
672 >        for (int i=0; i<size; i++)
673              s.writeObject(elementData[i]);
674  
675 <        if (modCount != expectedModCount) {
675 >        if (modCount != expectedModCount) {
676              throw new ConcurrentModificationException();
677          }
678  
# Line 614 | Line 684 | public class ArrayList<E> extends Abstra
684       */
685      private void readObject(java.io.ObjectInputStream s)
686          throws java.io.IOException, ClassNotFoundException {
687 <        // Read in size, and any hidden stuff
688 <        s.defaultReadObject();
687 >        // Read in size, and any hidden stuff
688 >        s.defaultReadObject();
689  
690          // Read in array length and allocate array
691          int arrayLength = s.readInt();
692          Object[] a = elementData = new Object[arrayLength];
693  
694 <        // Read in all elements in the proper order.
695 <        for (int i=0; i<size; i++)
694 >        // Read in all elements in the proper order.
695 >        for (int i=0; i<size; i++)
696              a[i] = s.readObject();
697      }
698  
629
699      /**
700 <     * Returns a list-iterator of the elements in this list (in proper
700 >     * Returns a list iterator over the elements in this list (in proper
701       * sequence), starting at the specified position in the list.
702 <     * Obeys the general contract of <tt>List.listIterator(int)</tt>.<p>
702 >     * The specified index indicates the first element that would be
703 >     * returned by an initial call to {@link ListIterator#next next}.
704 >     * An initial call to {@link ListIterator#previous previous} would
705 >     * return the element with the specified index minus one.
706 >     *
707 >     * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
708       *
635     * The list-iterator is <i>fail-fast</i>: if the list is structurally
636     * modified at any time after the Iterator is created, in any way except
637     * through the list-iterator's own <tt>remove</tt> or <tt>add</tt>
638     * methods, the list-iterator will throw a
639     * <tt>ConcurrentModificationException</tt>.  Thus, in the face of
640     * concurrent modification, the iterator fails quickly and cleanly, rather
641     * than risking arbitrary, non-deterministic behavior at an undetermined
642     * time in the future.
643     *
644     * @param index index of the first element to be returned from the
645     *              list-iterator (by a call to <tt>next</tt>)
646     * @return a ListIterator of the elements in this list (in proper
647     *         sequence), starting at the specified position in the list
709       * @throws IndexOutOfBoundsException {@inheritDoc}
649     * @see List#listIterator(int)
710       */
711      public ListIterator<E> listIterator(int index) {
712 <        if (index < 0 || index > size)
712 >        if (index < 0 || index > size)
713              throw new IndexOutOfBoundsException("Index: "+index);
714 <        return new ArrayListIterator(index);
714 >        return new ListItr(index);
715 >    }
716 >
717 >    /**
718 >     * Returns a list iterator over the elements in this list (in proper
719 >     * sequence).
720 >     *
721 >     * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
722 >     *
723 >     * @see #listIterator(int)
724 >     */
725 >    public ListIterator<E> listIterator() {
726 >        return new ListItr(0);
727      }
728  
729      /**
730       * Returns an iterator over the elements in this list in proper sequence.
731       *
732 +     * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
733 +     *
734       * @return an iterator over the elements in this list in proper sequence
735       */
736      public Iterator<E> iterator() {
737 <        return new ArrayListIterator(0);
737 >        return new Itr();
738 >    }
739 >
740 >    /**
741 >     * An optimized version of AbstractList.Itr
742 >     */
743 >    private class Itr implements Iterator<E> {
744 >        int cursor;       // index of next element to return
745 >        int lastRet = -1; // index of last element returned; -1 if no such
746 >        int expectedModCount = modCount;
747 >
748 >        public boolean hasNext() {
749 >            return cursor != size;
750 >        }
751 >
752 >        @SuppressWarnings("unchecked")
753 >        public E next() {
754 >            checkForComodification();
755 >            int i = cursor;
756 >            if (i >= size)
757 >                throw new NoSuchElementException();
758 >            Object[] elementData = ArrayList.this.elementData;
759 >            if (i >= elementData.length)
760 >                throw new ConcurrentModificationException();
761 >            cursor = i + 1;
762 >            return (E) elementData[lastRet = i];
763 >        }
764 >
765 >        public void remove() {
766 >            if (lastRet < 0)
767 >                throw new IllegalStateException();
768 >            checkForComodification();
769 >
770 >            try {
771 >                ArrayList.this.remove(lastRet);
772 >                cursor = lastRet;
773 >                lastRet = -1;
774 >                expectedModCount = modCount;
775 >            } catch (IndexOutOfBoundsException ex) {
776 >                throw new ConcurrentModificationException();
777 >            }
778 >        }
779 >
780 >        final void checkForComodification() {
781 >            if (modCount != expectedModCount)
782 >                throw new ConcurrentModificationException();
783 >        }
784      }
785  
786      /**
787 <     * A streamlined version of AbstractList.Itr
787 >     * An optimized version of AbstractList.ListItr
788       */
789 <    final class ArrayListIterator implements ListIterator<E> {
790 <        int cursor;           // index of next element to return;
791 <        int lastRet;          // index of last element, or -1 if no such
792 <        int expectedModCount; // to check for CME
789 >    private class ListItr extends Itr implements ListIterator<E> {
790 >        ListItr(int index) {
791 >            super();
792 >            cursor = index;
793 >        }
794  
795 <        ArrayListIterator(int index) {
796 <            cursor = index;
797 <            lastRet = -1;
677 <            expectedModCount = modCount;
678 <        }
795 >        public boolean hasPrevious() {
796 >            return cursor != 0;
797 >        }
798  
799 <        public boolean hasNext() {
800 <            return cursor < size;
801 <        }
799 >        public int nextIndex() {
800 >            return cursor;
801 >        }
802  
803 <        public boolean hasPrevious() {
804 <            return cursor > 0;
805 <        }
803 >        public int previousIndex() {
804 >            return cursor - 1;
805 >        }
806  
807 <        public int nextIndex() {
808 <            return cursor;
809 <        }
807 >        @SuppressWarnings("unchecked")
808 >        public E previous() {
809 >            checkForComodification();
810 >            int i = cursor - 1;
811 >            if (i < 0)
812 >                throw new NoSuchElementException();
813 >            Object[] elementData = ArrayList.this.elementData;
814 >            if (i >= elementData.length)
815 >                throw new ConcurrentModificationException();
816 >            cursor = i;
817 >            return (E) elementData[lastRet = i];
818 >        }
819  
820 <        public int previousIndex() {
821 <            return cursor - 1;
822 <        }
820 >        public void set(E e) {
821 >            if (lastRet < 0)
822 >                throw new IllegalStateException();
823 >            checkForComodification();
824 >
825 >            try {
826 >                ArrayList.this.set(lastRet, e);
827 >            } catch (IndexOutOfBoundsException ex) {
828 >                throw new ConcurrentModificationException();
829 >            }
830 >        }
831 >
832 >        public void add(E e) {
833 >            checkForComodification();
834  
835 <        public E next() {
697 <            if (expectedModCount == modCount) {
835 >            try {
836                  int i = cursor;
837 <                if (i < size) {
837 >                ArrayList.this.add(i, e);
838 >                cursor = i + 1;
839 >                lastRet = -1;
840 >                expectedModCount = modCount;
841 >            } catch (IndexOutOfBoundsException ex) {
842 >                throw new ConcurrentModificationException();
843 >            }
844 >        }
845 >    }
846 >
847 >    /**
848 >     * Returns a view of the portion of this list between the specified
849 >     * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.  (If
850 >     * {@code fromIndex} and {@code toIndex} are equal, the returned list is
851 >     * empty.)  The returned list is backed by this list, so non-structural
852 >     * changes in the returned list are reflected in this list, and vice-versa.
853 >     * The returned list supports all of the optional list operations.
854 >     *
855 >     * <p>This method eliminates the need for explicit range operations (of
856 >     * the sort that commonly exist for arrays).  Any operation that expects
857 >     * a list can be used as a range operation by passing a subList view
858 >     * instead of a whole list.  For example, the following idiom
859 >     * removes a range of elements from a list:
860 >     * <pre>
861 >     *      list.subList(from, to).clear();
862 >     * </pre>
863 >     * Similar idioms may be constructed for {@link #indexOf(Object)} and
864 >     * {@link #lastIndexOf(Object)}, and all of the algorithms in the
865 >     * {@link Collections} class can be applied to a subList.
866 >     *
867 >     * <p>The semantics of the list returned by this method become undefined if
868 >     * the backing list (i.e., this list) is <i>structurally modified</i> in
869 >     * any way other than via the returned list.  (Structural modifications are
870 >     * those that change the size of this list, or otherwise perturb it in such
871 >     * a fashion that iterations in progress may yield incorrect results.)
872 >     *
873 >     * @throws IndexOutOfBoundsException {@inheritDoc}
874 >     * @throws IllegalArgumentException {@inheritDoc}
875 >     */
876 >    public List<E> subList(int fromIndex, int toIndex) {
877 >        subListRangeCheck(fromIndex, toIndex, size);
878 >        return new SubList(this, 0, fromIndex, toIndex);
879 >    }
880 >
881 >    static void subListRangeCheck(int fromIndex, int toIndex, int size) {
882 >        if (fromIndex < 0)
883 >            throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
884 >        if (toIndex > size)
885 >            throw new IndexOutOfBoundsException("toIndex = " + toIndex);
886 >        if (fromIndex > toIndex)
887 >            throw new IllegalArgumentException("fromIndex(" + fromIndex +
888 >                                               ") > toIndex(" + toIndex + ")");
889 >    }
890 >
891 >    private class SubList extends AbstractList<E> implements RandomAccess {
892 >        private final AbstractList<E> parent;
893 >        private final int parentOffset;
894 >        private final int offset;
895 >        int size;
896 >
897 >        SubList(AbstractList<E> parent,
898 >                int offset, int fromIndex, int toIndex) {
899 >            this.parent = parent;
900 >            this.parentOffset = fromIndex;
901 >            this.offset = offset + fromIndex;
902 >            this.size = toIndex - fromIndex;
903 >            this.modCount = ArrayList.this.modCount;
904 >        }
905 >
906 >        public E set(int index, E e) {
907 >            rangeCheck(index);
908 >            checkForComodification();
909 >            E oldValue = ArrayList.this.elementData(offset + index);
910 >            ArrayList.this.elementData[offset + index] = e;
911 >            return oldValue;
912 >        }
913 >
914 >        public E get(int index) {
915 >            rangeCheck(index);
916 >            checkForComodification();
917 >            return ArrayList.this.elementData(offset + index);
918 >        }
919 >
920 >        public int size() {
921 >            checkForComodification();
922 >            return this.size;
923 >        }
924 >
925 >        public void add(int index, E e) {
926 >            rangeCheckForAdd(index);
927 >            checkForComodification();
928 >            parent.add(parentOffset + index, e);
929 >            this.modCount = parent.modCount;
930 >            this.size++;
931 >        }
932 >
933 >        public E remove(int index) {
934 >            rangeCheck(index);
935 >            checkForComodification();
936 >            E result = parent.remove(parentOffset + index);
937 >            this.modCount = parent.modCount;
938 >            this.size--;
939 >            return result;
940 >        }
941 >
942 >        protected void removeRange(int fromIndex, int toIndex) {
943 >            checkForComodification();
944 >            parent.removeRange(parentOffset + fromIndex,
945 >                               parentOffset + toIndex);
946 >            this.modCount = parent.modCount;
947 >            this.size -= toIndex - fromIndex;
948 >        }
949 >
950 >        public boolean addAll(Collection<? extends E> c) {
951 >            return addAll(this.size, c);
952 >        }
953 >
954 >        public boolean addAll(int index, Collection<? extends E> c) {
955 >            rangeCheckForAdd(index);
956 >            int cSize = c.size();
957 >            if (cSize==0)
958 >                return false;
959 >
960 >            checkForComodification();
961 >            parent.addAll(parentOffset + index, c);
962 >            this.modCount = parent.modCount;
963 >            this.size += cSize;
964 >            return true;
965 >        }
966 >
967 >        public Iterator<E> iterator() {
968 >            return listIterator();
969 >        }
970 >
971 >        public ListIterator<E> listIterator(final int index) {
972 >            checkForComodification();
973 >            rangeCheckForAdd(index);
974 >            final int offset = this.offset;
975 >
976 >            return new ListIterator<E>() {
977 >                int cursor = index;
978 >                int lastRet = -1;
979 >                int expectedModCount = ArrayList.this.modCount;
980 >
981 >                public boolean hasNext() {
982 >                    return cursor != SubList.this.size;
983 >                }
984 >
985 >                @SuppressWarnings("unchecked")
986 >                public E next() {
987 >                    checkForComodification();
988 >                    int i = cursor;
989 >                    if (i >= SubList.this.size)
990 >                        throw new NoSuchElementException();
991 >                    Object[] elementData = ArrayList.this.elementData;
992 >                    if (offset + i >= elementData.length)
993 >                        throw new ConcurrentModificationException();
994 >                    cursor = i + 1;
995 >                    return (E) elementData[offset + (lastRet = i)];
996 >                }
997 >
998 >                public boolean hasPrevious() {
999 >                    return cursor != 0;
1000 >                }
1001 >
1002 >                @SuppressWarnings("unchecked")
1003 >                public E previous() {
1004 >                    checkForComodification();
1005 >                    int i = cursor - 1;
1006 >                    if (i < 0)
1007 >                        throw new NoSuchElementException();
1008 >                    Object[] elementData = ArrayList.this.elementData;
1009 >                    if (offset + i >= elementData.length)
1010 >                        throw new ConcurrentModificationException();
1011 >                    cursor = i;
1012 >                    return (E) elementData[offset + (lastRet = i)];
1013 >                }
1014 >
1015 >                public int nextIndex() {
1016 >                    return cursor;
1017 >                }
1018 >
1019 >                public int previousIndex() {
1020 >                    return cursor - 1;
1021 >                }
1022 >
1023 >                public void remove() {
1024 >                    if (lastRet < 0)
1025 >                        throw new IllegalStateException();
1026 >                    checkForComodification();
1027 >
1028                      try {
1029 <                        E e = (E)elementData[i];
1030 <                        lastRet = i;
1031 <                        cursor = i + 1;
1032 <                        return e;
1033 <                    } catch (IndexOutOfBoundsException fallthrough) {
1029 >                        SubList.this.remove(lastRet);
1030 >                        cursor = lastRet;
1031 >                        lastRet = -1;
1032 >                        expectedModCount = ArrayList.this.modCount;
1033 >                    } catch (IndexOutOfBoundsException ex) {
1034 >                        throw new ConcurrentModificationException();
1035                      }
1036                  }
708            }
709            // Prefer reporting CME if applicable on failures
710            if (expectedModCount == modCount)
711                throw new NoSuchElementException();
712            throw new ConcurrentModificationException();
713        }
1037  
1038 <        public E previous() {
1039 <            if (expectedModCount == modCount) {
1040 <                int i = cursor - 1;
1041 <                if (i < size) {
1038 >                public void set(E e) {
1039 >                    if (lastRet < 0)
1040 >                        throw new IllegalStateException();
1041 >                    checkForComodification();
1042 >
1043                      try {
1044 <                        E e = (E)elementData[i];
1045 <                        lastRet = i;
1046 <                        cursor = i;
723 <                        return e;
724 <                    } catch (IndexOutOfBoundsException fallthrough) {
1044 >                        ArrayList.this.set(offset + lastRet, e);
1045 >                    } catch (IndexOutOfBoundsException ex) {
1046 >                        throw new ConcurrentModificationException();
1047                      }
1048                  }
1049 <            }
1050 <            if (expectedModCount == modCount)
1051 <                throw new NoSuchElementException();
1052 <            throw new ConcurrentModificationException();
1049 >
1050 >                public void add(E e) {
1051 >                    checkForComodification();
1052 >
1053 >                    try {
1054 >                        int i = cursor;
1055 >                        SubList.this.add(i, e);
1056 >                        cursor = i + 1;
1057 >                        lastRet = -1;
1058 >                        expectedModCount = ArrayList.this.modCount;
1059 >                    } catch (IndexOutOfBoundsException ex) {
1060 >                        throw new ConcurrentModificationException();
1061 >                    }
1062 >                }
1063 >
1064 >                final void checkForComodification() {
1065 >                    if (expectedModCount != ArrayList.this.modCount)
1066 >                        throw new ConcurrentModificationException();
1067 >                }
1068 >            };
1069          }
1070  
1071 <        public void remove() {
1072 <            if (lastRet < 0)
1073 <                throw new IllegalStateException();
1074 <            if (modCount != expectedModCount)
737 <                throw new ConcurrentModificationException();
738 <            ArrayList.this.remove(lastRet);
739 <            if (lastRet < cursor)
740 <                cursor--;
741 <            lastRet = -1;
742 <            expectedModCount = modCount;
743 <        }
744 <
745 <        public void set(E e) {
746 <            if (lastRet < 0)
747 <                throw new IllegalStateException();
748 <            if (modCount != expectedModCount)
749 <                throw new ConcurrentModificationException();
750 <            ArrayList.this.set(lastRet, e);
751 <            expectedModCount = modCount;
752 <        }
1071 >        public List<E> subList(int fromIndex, int toIndex) {
1072 >            subListRangeCheck(fromIndex, toIndex, size);
1073 >            return new SubList(this, offset, fromIndex, toIndex);
1074 >        }
1075  
1076 <        public void add(E e) {
1077 <            if (modCount != expectedModCount)
1076 >        private void rangeCheck(int index) {
1077 >            if (index < 0 || index >= this.size)
1078 >                throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1079 >        }
1080 >
1081 >        private void rangeCheckForAdd(int index) {
1082 >            if (index < 0 || index > this.size)
1083 >                throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1084 >        }
1085 >
1086 >        private String outOfBoundsMsg(int index) {
1087 >            return "Index: "+index+", Size: "+this.size;
1088 >        }
1089 >
1090 >        private void checkForComodification() {
1091 >            if (ArrayList.this.modCount != this.modCount)
1092                  throw new ConcurrentModificationException();
1093 <            ArrayList.this.add(cursor++, e);
758 <            lastRet = -1;
759 <            expectedModCount = modCount;
760 <        }
1093 >        }
1094      }
762
1095   }

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