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Comparing jsr166/src/main/java/util/ArrayList.java (file contents):
Revision 1.25 by jsr166, Tue Sep 11 15:38:02 2007 UTC vs.
Revision 1.47 by jsr166, Mon Dec 5 00:08:01 2016 UTC

# Line 1 | Line 1
1   /*
2 < * Copyright 1997-2007 Sun Microsystems, Inc.  All Rights Reserved.
2 > * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
3   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4   *
5   * This code is free software; you can redistribute it and/or modify it
6   * under the terms of the GNU General Public License version 2 only, as
7 < * published by the Free Software Foundation.  Sun designates this
7 > * published by the Free Software Foundation.  Oracle designates this
8   * particular file as subject to the "Classpath" exception as provided
9 < * by Sun in the LICENSE file that accompanied this code.
9 > * by Oracle in the LICENSE file that accompanied this code.
10   *
11   * This code is distributed in the hope that it will be useful, but WITHOUT
12   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# Line 18 | Line 18
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.
21 > * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 > * or visit www.oracle.com if you need additional information or have any
23 > * questions.
24   */
25  
26   package java.util;
27  
28 + import java.util.function.Consumer;
29 + import java.util.function.Predicate;
30 + import java.util.function.UnaryOperator;
31 +
32   /**
33 < * Resizable-array implementation of the <tt>List</tt> interface.  Implements
33 > * Resizable-array implementation of the {@code List} interface.  Implements
34   * all optional list operations, and permits all elements, including
35 < * <tt>null</tt>.  In addition to implementing the <tt>List</tt> interface,
35 > * {@code null}.  In addition to implementing the {@code List} interface,
36   * this class provides methods to manipulate the size of the array that is
37   * used internally to store the list.  (This class is roughly equivalent to
38 < * <tt>Vector</tt>, except that it is unsynchronized.)
38 > * {@code Vector}, except that it is unsynchronized.)
39   *
40 < * <p>The <tt>size</tt>, <tt>isEmpty</tt>, <tt>get</tt>, <tt>set</tt>,
41 < * <tt>iterator</tt>, and <tt>listIterator</tt> operations run in constant
42 < * time.  The <tt>add</tt> operation runs in <i>amortized constant time</i>,
40 > * <p>The {@code size}, {@code isEmpty}, {@code get}, {@code set},
41 > * {@code iterator}, and {@code listIterator} operations run in constant
42 > * time.  The {@code add} operation runs in <i>amortized constant time</i>,
43   * that is, adding n elements requires O(n) time.  All of the other operations
44   * run in linear time (roughly speaking).  The constant factor is low compared
45 < * to that for the <tt>LinkedList</tt> implementation.
45 > * to that for the {@code LinkedList} implementation.
46   *
47 < * <p>Each <tt>ArrayList</tt> instance has a <i>capacity</i>.  The capacity is
47 > * <p>Each {@code ArrayList} instance has a <i>capacity</i>.  The capacity is
48   * the size of the array used to store the elements in the list.  It is always
49   * at least as large as the list size.  As elements are added to an ArrayList,
50   * its capacity grows automatically.  The details of the growth policy are not
51   * specified beyond the fact that adding an element has constant amortized
52   * time cost.
53   *
54 < * <p>An application can increase the capacity of an <tt>ArrayList</tt> instance
55 < * before adding a large number of elements using the <tt>ensureCapacity</tt>
54 > * <p>An application can increase the capacity of an {@code ArrayList} instance
55 > * before adding a large number of elements using the {@code ensureCapacity}
56   * operation.  This may reduce the amount of incremental reallocation.
57   *
58   * <p><strong>Note that this implementation is not synchronized.</strong>
59 < * If multiple threads access an <tt>ArrayList</tt> instance concurrently,
59 > * If multiple threads access an {@code ArrayList} instance concurrently,
60   * and at least one of the threads modifies the list structurally, it
61   * <i>must</i> be synchronized externally.  (A structural modification is
62   * any operation that adds or deletes one or more elements, or explicitly
# Line 66 | Line 70 | package java.util;
70   * unsynchronized access to the list:<pre>
71   *   List list = Collections.synchronizedList(new ArrayList(...));</pre>
72   *
73 < * <p><a name="fail-fast"/>
73 > * <p id="fail-fast">
74   * The iterators returned by this class's {@link #iterator() iterator} and
75   * {@link #listIterator(int) listIterator} methods are <em>fail-fast</em>:
76   * if the list is structurally modified at any time after the iterator is
# Line 90 | Line 94 | package java.util;
94   * <a href="{@docRoot}/../technotes/guides/collections/index.html">
95   * Java Collections Framework</a>.
96   *
97 + * @param <E> the type of elements in this list
98 + *
99   * @author  Josh Bloch
100   * @author  Neal Gafter
101 < * @version %I%, %G%
102 < * @see     Collection
103 < * @see     List
104 < * @see     LinkedList
99 < * @see     Vector
101 > * @see     Collection
102 > * @see     List
103 > * @see     LinkedList
104 > * @see     Vector
105   * @since   1.2
106   */
102
107   public class ArrayList<E> extends AbstractList<E>
108          implements List<E>, RandomAccess, Cloneable, java.io.Serializable
109   {
110      private static final long serialVersionUID = 8683452581122892189L;
111  
112      /**
113 +     * Default initial capacity.
114 +     */
115 +    private static final int DEFAULT_CAPACITY = 10;
116 +
117 +    /**
118 +     * Shared empty array instance used for empty instances.
119 +     */
120 +    private static final Object[] EMPTY_ELEMENTDATA = {};
121 +
122 +    /**
123 +     * Shared empty array instance used for default sized empty instances. We
124 +     * distinguish this from EMPTY_ELEMENTDATA to know how much to inflate when
125 +     * first element is added.
126 +     */
127 +    private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA = {};
128 +
129 +    /**
130       * The array buffer into which the elements of the ArrayList are stored.
131 <     * The capacity of the ArrayList is the length of this array buffer.
131 >     * The capacity of the ArrayList is the length of this array buffer. Any
132 >     * empty ArrayList with elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
133 >     * will be expanded to DEFAULT_CAPACITY when the first element is added.
134       */
135 <    private transient Object[] elementData;
135 >    transient Object[] elementData; // non-private to simplify nested class access
136  
137      /**
138       * The size of the ArrayList (the number of elements it contains).
# Line 121 | Line 144 | public class ArrayList<E> extends Abstra
144      /**
145       * Constructs an empty list with the specified initial capacity.
146       *
147 <     * @param   initialCapacity   the initial capacity of the list
148 <     * @exception IllegalArgumentException if the specified initial capacity
149 <     *            is negative
147 >     * @param  initialCapacity  the initial capacity of the list
148 >     * @throws IllegalArgumentException if the specified initial capacity
149 >     *         is negative
150       */
151      public ArrayList(int initialCapacity) {
152 <        super();
153 <        if (initialCapacity < 0)
152 >        if (initialCapacity > 0) {
153 >            this.elementData = new Object[initialCapacity];
154 >        } else if (initialCapacity == 0) {
155 >            this.elementData = EMPTY_ELEMENTDATA;
156 >        } else {
157              throw new IllegalArgumentException("Illegal Capacity: "+
158                                                 initialCapacity);
159 <        this.elementData = new Object[initialCapacity];
159 >        }
160      }
161  
162      /**
163       * Constructs an empty list with an initial capacity of ten.
164       */
165      public ArrayList() {
166 <        this(10);
166 >        this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
167      }
168  
169      /**
# Line 149 | Line 175 | public class ArrayList<E> extends Abstra
175       * @throws NullPointerException if the specified collection is null
176       */
177      public ArrayList(Collection<? extends E> c) {
178 <        elementData = c.toArray();
179 <        size = elementData.length;
180 <        // c.toArray might (incorrectly) not return Object[] (see 6260652)
181 <        if (elementData.getClass() != Object[].class)
182 <            elementData = Arrays.copyOf(elementData, size, Object[].class);
178 >        elementData = c.toArray();
179 >        if ((size = elementData.length) != 0) {
180 >            // defend against c.toArray (incorrectly) not returning Object[]
181 >            // (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652)
182 >            if (elementData.getClass() != Object[].class)
183 >                elementData = Arrays.copyOf(elementData, size, Object[].class);
184 >        } else {
185 >            // replace with empty array.
186 >            this.elementData = EMPTY_ELEMENTDATA;
187 >        }
188      }
189  
190      /**
191 <     * Trims the capacity of this <tt>ArrayList</tt> instance to be the
191 >     * Trims the capacity of this {@code ArrayList} instance to be the
192       * list's current size.  An application can use this operation to minimize
193 <     * the storage of an <tt>ArrayList</tt> instance.
193 >     * the storage of an {@code ArrayList} instance.
194       */
195      public void trimToSize() {
196 <        modCount++;
197 <        int oldCapacity = elementData.length;
198 <        if (size < oldCapacity) {
199 <            elementData = Arrays.copyOf(elementData, size);
200 <        }
196 >        modCount++;
197 >        if (size < elementData.length) {
198 >            elementData = (size == 0)
199 >              ? EMPTY_ELEMENTDATA
200 >              : Arrays.copyOf(elementData, size);
201 >        }
202      }
203  
204      /**
205 <     * Increases the capacity of this <tt>ArrayList</tt> instance, if
205 >     * Increases the capacity of this {@code ArrayList} instance, if
206       * necessary, to ensure that it can hold at least the number of elements
207       * specified by the minimum capacity argument.
208       *
209 <     * @param   minCapacity   the desired minimum capacity
209 >     * @param minCapacity the desired minimum capacity
210       */
211      public void ensureCapacity(int minCapacity) {
212 <        modCount++;
213 <        int oldCapacity = elementData.length;
214 <        if (minCapacity > oldCapacity) {
215 <            Object oldData[] = elementData;
216 <            int newCapacity = (oldCapacity * 3)/2 + 1;
217 <            if (newCapacity < minCapacity)
218 <                newCapacity = minCapacity;
219 <            // minCapacity is usually close to size, so this is a win:
220 <            elementData = Arrays.copyOf(elementData, newCapacity);
221 <        }
212 >        if (minCapacity > elementData.length
213 >            && !(elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
214 >                 && minCapacity <= DEFAULT_CAPACITY)) {
215 >            modCount++;
216 >            grow(minCapacity);
217 >        }
218 >    }
219 >
220 >    /**
221 >     * The maximum size of array to allocate (unless necessary).
222 >     * Some VMs reserve some header words in an array.
223 >     * Attempts to allocate larger arrays may result in
224 >     * OutOfMemoryError: Requested array size exceeds VM limit
225 >     */
226 >    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
227 >
228 >    /**
229 >     * Increases the capacity to ensure that it can hold at least the
230 >     * number of elements specified by the minimum capacity argument.
231 >     *
232 >     * @param minCapacity the desired minimum capacity
233 >     * @throws OutOfMemoryError if minCapacity is less than zero
234 >     */
235 >    private Object[] grow(int minCapacity) {
236 >        return elementData = Arrays.copyOf(elementData,
237 >                                           newCapacity(minCapacity));
238 >    }
239 >
240 >    private Object[] grow() {
241 >        return grow(size + 1);
242 >    }
243 >
244 >    /**
245 >     * Returns a capacity at least as large as the given minimum capacity.
246 >     * Returns the current capacity increased by 50% if that suffices.
247 >     * Will not return a capacity greater than MAX_ARRAY_SIZE unless
248 >     * the given minimum capacity is greater than MAX_ARRAY_SIZE.
249 >     *
250 >     * @param minCapacity the desired minimum capacity
251 >     * @throws OutOfMemoryError if minCapacity is less than zero
252 >     */
253 >    private int newCapacity(int minCapacity) {
254 >        // overflow-conscious code
255 >        int oldCapacity = elementData.length;
256 >        int newCapacity = oldCapacity + (oldCapacity >> 1);
257 >        if (newCapacity - minCapacity <= 0) {
258 >            if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA)
259 >                return Math.max(DEFAULT_CAPACITY, minCapacity);
260 >            if (minCapacity < 0) // overflow
261 >                throw new OutOfMemoryError();
262 >            return minCapacity;
263 >        }
264 >        return (newCapacity - MAX_ARRAY_SIZE <= 0)
265 >            ? newCapacity
266 >            : hugeCapacity(minCapacity);
267 >    }
268 >
269 >    private static int hugeCapacity(int minCapacity) {
270 >        if (minCapacity < 0) // overflow
271 >            throw new OutOfMemoryError();
272 >        return (minCapacity > MAX_ARRAY_SIZE)
273 >            ? Integer.MAX_VALUE
274 >            : MAX_ARRAY_SIZE;
275      }
276  
277      /**
# Line 195 | Line 280 | public class ArrayList<E> extends Abstra
280       * @return the number of elements in this list
281       */
282      public int size() {
283 <        return size;
283 >        return size;
284      }
285  
286      /**
287 <     * Returns <tt>true</tt> if this list contains no elements.
287 >     * Returns {@code true} if this list contains no elements.
288       *
289 <     * @return <tt>true</tt> if this list contains no elements
289 >     * @return {@code true} if this list contains no elements
290       */
291      public boolean isEmpty() {
292 <        return size == 0;
292 >        return size == 0;
293      }
294  
295      /**
296 <     * Returns <tt>true</tt> if this list contains the specified element.
297 <     * More formally, returns <tt>true</tt> if and only if this list contains
298 <     * at least one element <tt>e</tt> such that
299 <     * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>.
296 >     * Returns {@code true} if this list contains the specified element.
297 >     * More formally, returns {@code true} if and only if this list contains
298 >     * at least one element {@code e} such that
299 >     * {@code Objects.equals(o, e)}.
300       *
301       * @param o element whose presence in this list is to be tested
302 <     * @return <tt>true</tt> if this list contains the specified element
302 >     * @return {@code true} if this list contains the specified element
303       */
304      public boolean contains(Object o) {
305 <        return indexOf(o) >= 0;
305 >        return indexOf(o) >= 0;
306      }
307  
308      /**
309       * Returns the index of the first occurrence of the specified element
310       * in this list, or -1 if this list does not contain the element.
311 <     * More formally, returns the lowest index <tt>i</tt> such that
312 <     * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>,
311 >     * More formally, returns the lowest index {@code i} such that
312 >     * {@code Objects.equals(o, get(i))},
313       * or -1 if there is no such index.
314       */
315      public int indexOf(Object o) {
316 <        if (o == null) {
317 <            for (int i = 0; i < size; i++)
318 <                if (elementData[i]==null)
319 <                    return i;
320 <        } else {
321 <            for (int i = 0; i < size; i++)
322 <                if (o.equals(elementData[i]))
323 <                    return i;
324 <        }
325 <        return -1;
316 >        if (o == null) {
317 >            for (int i = 0; i < size; i++)
318 >                if (elementData[i]==null)
319 >                    return i;
320 >        } else {
321 >            for (int i = 0; i < size; i++)
322 >                if (o.equals(elementData[i]))
323 >                    return i;
324 >        }
325 >        return -1;
326      }
327  
328      /**
329       * Returns the index of the last occurrence of the specified element
330       * in this list, or -1 if this list does not contain the element.
331 <     * More formally, returns the highest index <tt>i</tt> such that
332 <     * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>,
331 >     * More formally, returns the highest index {@code i} such that
332 >     * {@code Objects.equals(o, get(i))},
333       * or -1 if there is no such index.
334       */
335      public int lastIndexOf(Object o) {
336 <        if (o == null) {
337 <            for (int i = size-1; i >= 0; i--)
338 <                if (elementData[i]==null)
339 <                    return i;
340 <        } else {
341 <            for (int i = size-1; i >= 0; i--)
342 <                if (o.equals(elementData[i]))
343 <                    return i;
344 <        }
345 <        return -1;
336 >        if (o == null) {
337 >            for (int i = size-1; i >= 0; i--)
338 >                if (elementData[i]==null)
339 >                    return i;
340 >        } else {
341 >            for (int i = size-1; i >= 0; i--)
342 >                if (o.equals(elementData[i]))
343 >                    return i;
344 >        }
345 >        return -1;
346      }
347  
348      /**
349 <     * Returns a shallow copy of this <tt>ArrayList</tt> instance.  (The
349 >     * Returns a shallow copy of this {@code ArrayList} instance.  (The
350       * elements themselves are not copied.)
351       *
352 <     * @return a clone of this <tt>ArrayList</tt> instance
352 >     * @return a clone of this {@code ArrayList} instance
353       */
354      public Object clone() {
355 <        try {
356 <            @SuppressWarnings("unchecked")
357 <                ArrayList<E> v = (ArrayList<E>) super.clone();
358 <            v.elementData = Arrays.copyOf(elementData, size);
359 <            v.modCount = 0;
360 <            return v;
361 <        } catch (CloneNotSupportedException e) {
362 <            // this shouldn't happen, since we are Cloneable
363 <            throw new InternalError();
279 <        }
355 >        try {
356 >            ArrayList<?> v = (ArrayList<?>) super.clone();
357 >            v.elementData = Arrays.copyOf(elementData, size);
358 >            v.modCount = 0;
359 >            return v;
360 >        } catch (CloneNotSupportedException e) {
361 >            // this shouldn't happen, since we are Cloneable
362 >            throw new InternalError(e);
363 >        }
364      }
365  
366      /**
# Line 308 | Line 392 | public class ArrayList<E> extends Abstra
392       * <p>If the list fits in the specified array with room to spare
393       * (i.e., the array has more elements than the list), the element in
394       * the array immediately following the end of the collection is set to
395 <     * <tt>null</tt>.  (This is useful in determining the length of the
395 >     * {@code null}.  (This is useful in determining the length of the
396       * list <i>only</i> if the caller knows that the list does not contain
397       * any null elements.)
398       *
# Line 326 | Line 410 | public class ArrayList<E> extends Abstra
410          if (a.length < size)
411              // Make a new array of a's runtime type, but my contents:
412              return (T[]) Arrays.copyOf(elementData, size, a.getClass());
413 <        System.arraycopy(elementData, 0, a, 0, size);
413 >        System.arraycopy(elementData, 0, a, 0, size);
414          if (a.length > size)
415              a[size] = null;
416          return a;
# Line 336 | Line 420 | public class ArrayList<E> extends Abstra
420  
421      @SuppressWarnings("unchecked")
422      E elementData(int index) {
423 <        return (E) elementData[index];
423 >        return (E) elementData[index];
424 >    }
425 >
426 >    @SuppressWarnings("unchecked")
427 >    static <E> E elementAt(Object[] es, int index) {
428 >        return (E) es[index];
429      }
430  
431      /**
# Line 347 | Line 436 | public class ArrayList<E> extends Abstra
436       * @throws IndexOutOfBoundsException {@inheritDoc}
437       */
438      public E get(int index) {
439 <        rangeCheck(index);
440 <
352 <        return elementData(index);
439 >        Objects.checkIndex(index, size);
440 >        return elementData(index);
441      }
442  
443      /**
# Line 362 | Line 450 | public class ArrayList<E> extends Abstra
450       * @throws IndexOutOfBoundsException {@inheritDoc}
451       */
452      public E set(int index, E element) {
453 <        rangeCheck(index);
453 >        Objects.checkIndex(index, size);
454 >        E oldValue = elementData(index);
455 >        elementData[index] = element;
456 >        return oldValue;
457 >    }
458  
459 <        E oldValue = elementData(index);
460 <        elementData[index] = element;
461 <        return oldValue;
459 >    /**
460 >     * This helper method split out from add(E) to keep method
461 >     * bytecode size under 35 (the -XX:MaxInlineSize default value),
462 >     * which helps when add(E) is called in a C1-compiled loop.
463 >     */
464 >    private void add(E e, Object[] elementData, int s) {
465 >        if (s == elementData.length)
466 >            elementData = grow();
467 >        elementData[s] = e;
468 >        size = s + 1;
469      }
470  
471      /**
472       * Appends the specified element to the end of this list.
473       *
474       * @param e element to be appended to this list
475 <     * @return <tt>true</tt> (as specified by {@link Collection#add})
475 >     * @return {@code true} (as specified by {@link Collection#add})
476       */
477      public boolean add(E e) {
478 <        ensureCapacity(size + 1);  // Increments modCount!!
479 <        elementData[size++] = e;
480 <        return true;
478 >        modCount++;
479 >        add(e, elementData, size);
480 >        return true;
481      }
482  
483      /**
# Line 391 | Line 490 | public class ArrayList<E> extends Abstra
490       * @throws IndexOutOfBoundsException {@inheritDoc}
491       */
492      public void add(int index, E element) {
493 <        rangeCheckForAdd(index);
494 <
495 <        ensureCapacity(size+1);  // Increments modCount!!
496 <        System.arraycopy(elementData, index, elementData, index + 1,
497 <                         size - index);
498 <        elementData[index] = element;
499 <        size++;
493 >        rangeCheckForAdd(index);
494 >        modCount++;
495 >        final int s;
496 >        Object[] elementData;
497 >        if ((s = size) == (elementData = this.elementData).length)
498 >            elementData = grow();
499 >        System.arraycopy(elementData, index,
500 >                         elementData, index + 1,
501 >                         s - index);
502 >        elementData[index] = element;
503 >        size = s + 1;
504 >        // checkInvariants();
505      }
506  
507      /**
# Line 410 | Line 514 | public class ArrayList<E> extends Abstra
514       * @throws IndexOutOfBoundsException {@inheritDoc}
515       */
516      public E remove(int index) {
517 <        rangeCheck(index);
517 >        Objects.checkIndex(index, size);
518  
519 <        modCount++;
520 <        E oldValue = elementData(index);
519 >        modCount++;
520 >        E oldValue = elementData(index);
521  
522 <        int numMoved = size - index - 1;
523 <        if (numMoved > 0)
524 <            System.arraycopy(elementData, index+1, elementData, index,
525 <                             numMoved);
526 <        elementData[--size] = null; // Let gc do its work
522 >        int numMoved = size - index - 1;
523 >        if (numMoved > 0)
524 >            System.arraycopy(elementData, index+1, elementData, index,
525 >                             numMoved);
526 >        elementData[--size] = null; // clear to let GC do its work
527  
528 <        return oldValue;
528 >        // checkInvariants();
529 >        return oldValue;
530      }
531  
532      /**
533       * Removes the first occurrence of the specified element from this list,
534       * if it is present.  If the list does not contain the element, it is
535       * unchanged.  More formally, removes the element with the lowest index
536 <     * <tt>i</tt> such that
537 <     * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>
538 <     * (if such an element exists).  Returns <tt>true</tt> if this list
536 >     * {@code i} such that
537 >     * {@code Objects.equals(o, get(i))}
538 >     * (if such an element exists).  Returns {@code true} if this list
539       * contained the specified element (or equivalently, if this list
540       * changed as a result of the call).
541       *
542       * @param o element to be removed from this list, if present
543 <     * @return <tt>true</tt> if this list contained the specified element
543 >     * @return {@code true} if this list contained the specified element
544       */
545      public boolean remove(Object o) {
546 <        if (o == null) {
546 >        if (o == null) {
547 >            for (int index = 0; index < size; index++)
548 >                if (elementData[index] == null) {
549 >                    fastRemove(index);
550 >                    return true;
551 >                }
552 >        } else {
553              for (int index = 0; index < size; index++)
554 <                if (elementData[index] == null) {
555 <                    fastRemove(index);
556 <                    return true;
557 <                }
447 <        } else {
448 <            for (int index = 0; index < size; index++)
449 <                if (o.equals(elementData[index])) {
450 <                    fastRemove(index);
451 <                    return true;
452 <                }
554 >                if (o.equals(elementData[index])) {
555 >                    fastRemove(index);
556 >                    return true;
557 >                }
558          }
559 <        return false;
559 >        return false;
560      }
561  
562 <    /*
562 >    /**
563       * Private remove method that skips bounds checking and does not
564       * return the value removed.
565       */
# Line 464 | Line 569 | public class ArrayList<E> extends Abstra
569          if (numMoved > 0)
570              System.arraycopy(elementData, index+1, elementData, index,
571                               numMoved);
572 <        elementData[--size] = null; // Let gc do its work
572 >        elementData[--size] = null; // clear to let GC do its work
573      }
574  
575      /**
# Line 472 | Line 577 | public class ArrayList<E> extends Abstra
577       * be empty after this call returns.
578       */
579      public void clear() {
580 <        modCount++;
581 <
582 <        // Let gc do its work
583 <        for (int i = 0; i < size; i++)
479 <            elementData[i] = null;
480 <
481 <        size = 0;
580 >        modCount++;
581 >        final Object[] es = elementData;
582 >        for (int to = size, i = size = 0; i < to; i++)
583 >            es[i] = null;
584      }
585  
586      /**
# Line 491 | Line 593 | public class ArrayList<E> extends Abstra
593       * list is nonempty.)
594       *
595       * @param c collection containing elements to be added to this list
596 <     * @return <tt>true</tt> if this list changed as a result of the call
596 >     * @return {@code true} if this list changed as a result of the call
597       * @throws NullPointerException if the specified collection is null
598       */
599      public boolean addAll(Collection<? extends E> c) {
600 <        Object[] a = c.toArray();
600 >        Object[] a = c.toArray();
601 >        modCount++;
602          int numNew = a.length;
603 <        ensureCapacity(size + numNew);  // Increments modCount
604 <        System.arraycopy(a, 0, elementData, size, numNew);
605 <        size += numNew;
606 <        return numNew != 0;
603 >        if (numNew == 0)
604 >            return false;
605 >        Object[] elementData;
606 >        final int s;
607 >        if (numNew > (elementData = this.elementData).length - (s = size))
608 >            elementData = grow(s + numNew);
609 >        System.arraycopy(a, 0, elementData, s, numNew);
610 >        size = s + numNew;
611 >        // checkInvariants();
612 >        return true;
613      }
614  
615      /**
# Line 514 | Line 623 | public class ArrayList<E> extends Abstra
623       * @param index index at which to insert the first element from the
624       *              specified collection
625       * @param c collection containing elements to be added to this list
626 <     * @return <tt>true</tt> if this list changed as a result of the call
626 >     * @return {@code true} if this list changed as a result of the call
627       * @throws IndexOutOfBoundsException {@inheritDoc}
628       * @throws NullPointerException if the specified collection is null
629       */
630      public boolean addAll(int index, Collection<? extends E> c) {
631 <        rangeCheckForAdd(index);
631 >        rangeCheckForAdd(index);
632  
633 <        Object[] a = c.toArray();
634 <        int numNew = a.length;
635 <        ensureCapacity(size + numNew);  // Increments modCount
636 <
637 <        int numMoved = size - index;
638 <        if (numMoved > 0)
639 <            System.arraycopy(elementData, index, elementData, index + numNew,
640 <                             numMoved);
633 >        Object[] a = c.toArray();
634 >        modCount++;
635 >        int numNew = a.length;
636 >        if (numNew == 0)
637 >            return false;
638 >        Object[] elementData;
639 >        final int s;
640 >        if (numNew > (elementData = this.elementData).length - (s = size))
641 >            elementData = grow(s + numNew);
642  
643 +        int numMoved = s - index;
644 +        if (numMoved > 0)
645 +            System.arraycopy(elementData, index,
646 +                             elementData, index + numNew,
647 +                             numMoved);
648          System.arraycopy(a, 0, elementData, index, numNew);
649 <        size += numNew;
650 <        return numNew != 0;
649 >        size = s + numNew;
650 >        // checkInvariants();
651 >        return true;
652      }
653  
654      /**
# Line 545 | Line 661 | public class ArrayList<E> extends Abstra
661       * @throws IndexOutOfBoundsException if {@code fromIndex} or
662       *         {@code toIndex} is out of range
663       *         ({@code fromIndex < 0 ||
548     *          fromIndex >= size() ||
664       *          toIndex > size() ||
665       *          toIndex < fromIndex})
666       */
667      protected void removeRange(int fromIndex, int toIndex) {
668 <        modCount++;
669 <        int numMoved = size - toIndex;
670 <        System.arraycopy(elementData, toIndex, elementData, fromIndex,
671 <                         numMoved);
672 <
673 <        // Let gc do its work
674 <        int newSize = size - (toIndex-fromIndex);
560 <        while (size != newSize)
561 <            elementData[--size] = null;
668 >        if (fromIndex > toIndex) {
669 >            throw new IndexOutOfBoundsException(
670 >                    outOfBoundsMsg(fromIndex, toIndex));
671 >        }
672 >        modCount++;
673 >        shiftTailOverGap(elementData, fromIndex, toIndex);
674 >        // checkInvariants();
675      }
676  
677 <    /**
678 <     * Checks if the given index is in range.  If not, throws an appropriate
679 <     * runtime exception.  This method does *not* check if the index is
680 <     * negative: It is always used immediately prior to an array access,
681 <     * which throws an ArrayIndexOutOfBoundsException if index is negative.
569 <     */
570 <    private void rangeCheck(int index) {
571 <        if (index >= size)
572 <            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
677 >    /** Erases the gap from lo to hi, by sliding down following elements. */
678 >    private void shiftTailOverGap(Object[] es, int lo, int hi) {
679 >        System.arraycopy(es, hi, es, lo, size - hi);
680 >        for (int to = size, i = (size -= hi - lo); i < to; i++)
681 >            es[i] = null;
682      }
683  
684      /**
685       * A version of rangeCheck used by add and addAll.
686       */
687      private void rangeCheckForAdd(int index) {
688 <        if (index > size || index < 0)
689 <            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
688 >        if (index > size || index < 0)
689 >            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
690      }
691  
692      /**
# Line 586 | Line 695 | public class ArrayList<E> extends Abstra
695       * this "outlining" performs best with both server and client VMs.
696       */
697      private String outOfBoundsMsg(int index) {
698 <        return "Index: "+index+", Size: "+size;
698 >        return "Index: "+index+", Size: "+size;
699 >    }
700 >
701 >    /**
702 >     * A version used in checking (fromIndex > toIndex) condition
703 >     */
704 >    private static String outOfBoundsMsg(int fromIndex, int toIndex) {
705 >        return "From Index: " + fromIndex + " > To Index: " + toIndex;
706      }
707  
708      /**
# Line 596 | Line 712 | public class ArrayList<E> extends Abstra
712       * @param c collection containing elements to be removed from this list
713       * @return {@code true} if this list changed as a result of the call
714       * @throws ClassCastException if the class of an element of this list
715 <     *         is incompatible with the specified collection (optional)
715 >     *         is incompatible with the specified collection
716 >     * (<a href="Collection.html#optional-restrictions">optional</a>)
717       * @throws NullPointerException if this list contains a null element and the
718 <     *         specified collection does not permit null elements (optional),
718 >     *         specified collection does not permit null elements
719 >     * (<a href="Collection.html#optional-restrictions">optional</a>),
720       *         or if the specified collection is null
721       * @see Collection#contains(Object)
722       */
723      public boolean removeAll(Collection<?> c) {
724 <        return batchRemove(c, false);
724 >        return batchRemove(c, false, 0, size);
725      }
726  
727      /**
# Line 614 | Line 732 | public class ArrayList<E> extends Abstra
732       * @param c collection containing elements to be retained in this list
733       * @return {@code true} if this list changed as a result of the call
734       * @throws ClassCastException if the class of an element of this list
735 <     *         is incompatible with the specified collection (optional)
735 >     *         is incompatible with the specified collection
736 >     * (<a href="Collection.html#optional-restrictions">optional</a>)
737       * @throws NullPointerException if this list contains a null element and the
738 <     *         specified collection does not permit null elements (optional),
738 >     *         specified collection does not permit null elements
739 >     * (<a href="Collection.html#optional-restrictions">optional</a>),
740       *         or if the specified collection is null
741       * @see Collection#contains(Object)
742       */
743      public boolean retainAll(Collection<?> c) {
744 <        return batchRemove(c, true);
744 >        return batchRemove(c, true, 0, size);
745      }
746  
747 <    private boolean batchRemove(Collection<?> c, boolean complement) {
748 <        final Object[] elementData = this.elementData;
749 <        int r = 0, w = 0;
750 <        boolean modified = false;
751 <        try {
752 <            for (; r < size; r++)
753 <                if (c.contains(elementData[r]) == complement)
754 <                    elementData[w++] = elementData[r];
755 <        } finally {
756 <            // Preserve behavioral compatibility with AbstractCollection,
757 <            // even if c.contains() throws.
758 <            if (r != size) {
759 <                System.arraycopy(elementData, r,
760 <                                 elementData, w,
761 <                                 size - r);
762 <                w += size - r;
763 <            }
764 <            if (w != size) {
765 <                for (int i = w; i < size; i++)
766 <                    elementData[i] = null;
767 <                modCount += size - w;
768 <                size = w;
769 <                modified = true;
770 <            }
771 <        }
772 <        return modified;
747 >    boolean batchRemove(Collection<?> c, boolean complement,
748 >                        final int from, final int end) {
749 >        Objects.requireNonNull(c);
750 >        final Object[] es = elementData;
751 >        final boolean modified;
752 >        int r;
753 >        // Optimize for initial run of survivors
754 >        for (r = from; r < end && c.contains(es[r]) == complement; r++)
755 >            ;
756 >        if (modified = (r < end)) {
757 >            int w = r++;
758 >            try {
759 >                for (Object e; r < end; r++)
760 >                    if (c.contains(e = es[r]) == complement)
761 >                        es[w++] = e;
762 >            } catch (Throwable ex) {
763 >                // Preserve behavioral compatibility with AbstractCollection,
764 >                // even if c.contains() throws.
765 >                System.arraycopy(es, r, es, w, end - r);
766 >                w += end - r;
767 >                throw ex;
768 >            } finally {
769 >                modCount += end - w;
770 >                shiftTailOverGap(es, w, end);
771 >            }
772 >        }
773 >        // checkInvariants();
774 >        return modified;
775      }
776  
777      /**
778 <     * Save the state of the <tt>ArrayList</tt> instance to a stream (that
779 <     * is, serialize it).
778 >     * Saves the state of the {@code ArrayList} instance to a stream
779 >     * (that is, serializes it).
780       *
781 <     * @serialData The length of the array backing the <tt>ArrayList</tt>
781 >     * @param s the stream
782 >     * @throws java.io.IOException if an I/O error occurs
783 >     * @serialData The length of the array backing the {@code ArrayList}
784       *             instance is emitted (int), followed by all of its elements
785 <     *             (each an <tt>Object</tt>) in the proper order.
785 >     *             (each an {@code Object}) in the proper order.
786       */
787      private void writeObject(java.io.ObjectOutputStream s)
788 <        throws java.io.IOException{
789 <        // Write out element count, and any hidden stuff
790 <        int expectedModCount = modCount;
791 <        s.defaultWriteObject();
788 >        throws java.io.IOException {
789 >        // Write out element count, and any hidden stuff
790 >        int expectedModCount = modCount;
791 >        s.defaultWriteObject();
792  
793 <        // Write out array length
794 <        s.writeInt(elementData.length);
793 >        // Write out size as capacity for behavioural compatibility with clone()
794 >        s.writeInt(size);
795  
796 <        // Write out all elements in the proper order.
797 <        for (int i=0; i<size; i++)
796 >        // Write out all elements in the proper order.
797 >        for (int i=0; i<size; i++) {
798              s.writeObject(elementData[i]);
799 +        }
800  
801 <        if (modCount != expectedModCount) {
801 >        if (modCount != expectedModCount) {
802              throw new ConcurrentModificationException();
803          }
679
804      }
805  
806      /**
807 <     * Reconstitute the <tt>ArrayList</tt> instance from a stream (that is,
808 <     * deserialize it).
807 >     * Reconstitutes the {@code ArrayList} instance from a stream (that is,
808 >     * deserializes it).
809 >     * @param s the stream
810 >     * @throws ClassNotFoundException if the class of a serialized object
811 >     *         could not be found
812 >     * @throws java.io.IOException if an I/O error occurs
813       */
814      private void readObject(java.io.ObjectInputStream s)
815          throws java.io.IOException, ClassNotFoundException {
688        // Read in size, and any hidden stuff
689        s.defaultReadObject();
816  
817 <        // Read in array length and allocate array
818 <        int arrayLength = s.readInt();
819 <        Object[] a = elementData = new Object[arrayLength];
820 <
821 <        // Read in all elements in the proper order.
822 <        for (int i=0; i<size; i++)
823 <            a[i] = s.readObject();
817 >        // Read in size, and any hidden stuff
818 >        s.defaultReadObject();
819 >
820 >        // Read in capacity
821 >        s.readInt(); // ignored
822 >
823 >        if (size > 0) {
824 >            // like clone(), allocate array based upon size not capacity
825 >            Object[] elements = new Object[size];
826 >
827 >            // Read in all elements in the proper order.
828 >            for (int i = 0; i < size; i++) {
829 >                elements[i] = s.readObject();
830 >            }
831 >
832 >            elementData = elements;
833 >        } else if (size == 0) {
834 >            elementData = EMPTY_ELEMENTDATA;
835 >        } else {
836 >            throw new java.io.InvalidObjectException("Invalid size: " + size);
837 >        }
838      }
839  
840      /**
# Line 710 | Line 850 | public class ArrayList<E> extends Abstra
850       * @throws IndexOutOfBoundsException {@inheritDoc}
851       */
852      public ListIterator<E> listIterator(int index) {
853 <        if (index < 0 || index > size)
854 <            throw new IndexOutOfBoundsException("Index: "+index);
715 <        return new ListItr(index);
853 >        rangeCheckForAdd(index);
854 >        return new ListItr(index);
855      }
856  
857      /**
# Line 724 | Line 863 | public class ArrayList<E> extends Abstra
863       * @see #listIterator(int)
864       */
865      public ListIterator<E> listIterator() {
866 <        return new ListItr(0);
866 >        return new ListItr(0);
867      }
868  
869      /**
# Line 735 | Line 874 | public class ArrayList<E> extends Abstra
874       * @return an iterator over the elements in this list in proper sequence
875       */
876      public Iterator<E> iterator() {
877 <        return new Itr();
877 >        return new Itr();
878      }
879  
880      /**
881       * An optimized version of AbstractList.Itr
882       */
883      private class Itr implements Iterator<E> {
884 <        int cursor;       // index of next element to return
885 <        int lastRet = -1; // index of last element returned; -1 if no such
886 <        int expectedModCount = modCount;
884 >        int cursor;       // index of next element to return
885 >        int lastRet = -1; // index of last element returned; -1 if no such
886 >        int expectedModCount = modCount;
887 >
888 >        // prevent creating a synthetic constructor
889 >        Itr() {}
890  
891 <        public boolean hasNext() {
891 >        public boolean hasNext() {
892              return cursor != size;
893 <        }
893 >        }
894  
895 <        @SuppressWarnings("unchecked")
896 <        public E next() {
895 >        @SuppressWarnings("unchecked")
896 >        public E next() {
897              checkForComodification();
898 <            int i = cursor;
899 <            if (i >= size)
900 <                throw new NoSuchElementException();
901 <            Object[] elementData = ArrayList.this.elementData;
902 <            if (i >= elementData.length)
903 <                throw new ConcurrentModificationException();
904 <            cursor = i + 1;
905 <            return (E) elementData[lastRet = i];
906 <        }
907 <
908 <        public void remove() {
909 <            if (lastRet < 0)
910 <                throw new IllegalStateException();
898 >            int i = cursor;
899 >            if (i >= size)
900 >                throw new NoSuchElementException();
901 >            Object[] elementData = ArrayList.this.elementData;
902 >            if (i >= elementData.length)
903 >                throw new ConcurrentModificationException();
904 >            cursor = i + 1;
905 >            return (E) elementData[lastRet = i];
906 >        }
907 >
908 >        public void remove() {
909 >            if (lastRet < 0)
910 >                throw new IllegalStateException();
911              checkForComodification();
912  
913 <            try {
914 <                ArrayList.this.remove(lastRet);
915 <                cursor = lastRet;
916 <                lastRet = -1;
917 <                expectedModCount = modCount;
918 <            } catch (IndexOutOfBoundsException ex) {
919 <                throw new ConcurrentModificationException();
920 <            }
921 <        }
922 <
923 <        final void checkForComodification() {
924 <            if (modCount != expectedModCount)
925 <                throw new ConcurrentModificationException();
926 <        }
913 >            try {
914 >                ArrayList.this.remove(lastRet);
915 >                cursor = lastRet;
916 >                lastRet = -1;
917 >                expectedModCount = modCount;
918 >            } catch (IndexOutOfBoundsException ex) {
919 >                throw new ConcurrentModificationException();
920 >            }
921 >        }
922 >
923 >        @Override
924 >        public void forEachRemaining(Consumer<? super E> action) {
925 >            Objects.requireNonNull(action);
926 >            final int size = ArrayList.this.size;
927 >            int i = cursor;
928 >            if (i < size) {
929 >                final Object[] es = elementData;
930 >                if (i >= es.length)
931 >                    throw new ConcurrentModificationException();
932 >                for (; i < size && modCount == expectedModCount; i++)
933 >                    action.accept(elementAt(es, i));
934 >                // update once at end to reduce heap write traffic
935 >                cursor = i;
936 >                lastRet = i - 1;
937 >                checkForComodification();
938 >            }
939 >        }
940 >
941 >        final void checkForComodification() {
942 >            if (modCount != expectedModCount)
943 >                throw new ConcurrentModificationException();
944 >        }
945      }
946  
947      /**
948       * An optimized version of AbstractList.ListItr
949       */
950      private class ListItr extends Itr implements ListIterator<E> {
951 <        ListItr(int index) {
952 <            super();
953 <            cursor = index;
954 <        }
955 <
956 <        public boolean hasPrevious() {
957 <            return cursor != 0;
958 <        }
959 <
960 <        public int nextIndex() {
961 <            return cursor;
962 <        }
803 <
804 <        public int previousIndex() {
805 <            return cursor - 1;
806 <        }
951 >        ListItr(int index) {
952 >            super();
953 >            cursor = index;
954 >        }
955 >
956 >        public boolean hasPrevious() {
957 >            return cursor != 0;
958 >        }
959 >
960 >        public int nextIndex() {
961 >            return cursor;
962 >        }
963  
964 <        @SuppressWarnings("unchecked")
964 >        public int previousIndex() {
965 >            return cursor - 1;
966 >        }
967 >
968 >        @SuppressWarnings("unchecked")
969          public E previous() {
970 <            checkForComodification();
971 <            int i = cursor - 1;
972 <            if (i < 0)
973 <                throw new NoSuchElementException();
974 <            Object[] elementData = ArrayList.this.elementData;
975 <            if (i >= elementData.length)
976 <                throw new ConcurrentModificationException();
977 <            cursor = i;
978 <            return (E) elementData[lastRet = i];
970 >            checkForComodification();
971 >            int i = cursor - 1;
972 >            if (i < 0)
973 >                throw new NoSuchElementException();
974 >            Object[] elementData = ArrayList.this.elementData;
975 >            if (i >= elementData.length)
976 >                throw new ConcurrentModificationException();
977 >            cursor = i;
978 >            return (E) elementData[lastRet = i];
979          }
980  
981 <        public void set(E e) {
982 <            if (lastRet < 0)
983 <                throw new IllegalStateException();
981 >        public void set(E e) {
982 >            if (lastRet < 0)
983 >                throw new IllegalStateException();
984              checkForComodification();
985  
986 <            try {
987 <                ArrayList.this.set(lastRet, e);
988 <            } catch (IndexOutOfBoundsException ex) {
989 <                throw new ConcurrentModificationException();
990 <            }
991 <        }
986 >            try {
987 >                ArrayList.this.set(lastRet, e);
988 >            } catch (IndexOutOfBoundsException ex) {
989 >                throw new ConcurrentModificationException();
990 >            }
991 >        }
992  
993 <        public void add(E e) {
993 >        public void add(E e) {
994              checkForComodification();
995  
996 <            try {
997 <                int i = cursor;
998 <                ArrayList.this.add(i, e);
999 <                cursor = i + 1;
1000 <                lastRet = -1;
1001 <                expectedModCount = modCount;
1002 <            } catch (IndexOutOfBoundsException ex) {
1003 <                throw new ConcurrentModificationException();
1004 <            }
1005 <        }
996 >            try {
997 >                int i = cursor;
998 >                ArrayList.this.add(i, e);
999 >                cursor = i + 1;
1000 >                lastRet = -1;
1001 >                expectedModCount = modCount;
1002 >            } catch (IndexOutOfBoundsException ex) {
1003 >                throw new ConcurrentModificationException();
1004 >            }
1005 >        }
1006      }
1007  
1008      /**
# Line 875 | Line 1035 | public class ArrayList<E> extends Abstra
1035       * @throws IllegalArgumentException {@inheritDoc}
1036       */
1037      public List<E> subList(int fromIndex, int toIndex) {
1038 <        subListRangeCheck(fromIndex, toIndex, size);
1039 <        return new SubList(this, 0, fromIndex, toIndex);
1038 >        subListRangeCheck(fromIndex, toIndex, size);
1039 >        return new SubList<>(this, fromIndex, toIndex);
1040 >    }
1041 >
1042 >    private static class SubList<E> extends AbstractList<E> implements RandomAccess {
1043 >        private final ArrayList<E> root;
1044 >        private final SubList<E> parent;
1045 >        private final int offset;
1046 >        private int size;
1047 >
1048 >        /**
1049 >         * Constructs a sublist of an arbitrary ArrayList.
1050 >         */
1051 >        public SubList(ArrayList<E> root, int fromIndex, int toIndex) {
1052 >            this.root = root;
1053 >            this.parent = null;
1054 >            this.offset = fromIndex;
1055 >            this.size = toIndex - fromIndex;
1056 >            this.modCount = root.modCount;
1057 >        }
1058 >
1059 >        /**
1060 >         * Constructs a sublist of another SubList.
1061 >         */
1062 >        private SubList(SubList<E> parent, int fromIndex, int toIndex) {
1063 >            this.root = parent.root;
1064 >            this.parent = parent;
1065 >            this.offset = parent.offset + fromIndex;
1066 >            this.size = toIndex - fromIndex;
1067 >            this.modCount = root.modCount;
1068 >        }
1069 >
1070 >        public E set(int index, E element) {
1071 >            Objects.checkIndex(index, size);
1072 >            checkForComodification();
1073 >            E oldValue = root.elementData(offset + index);
1074 >            root.elementData[offset + index] = element;
1075 >            return oldValue;
1076 >        }
1077 >
1078 >        public E get(int index) {
1079 >            Objects.checkIndex(index, size);
1080 >            checkForComodification();
1081 >            return root.elementData(offset + index);
1082 >        }
1083 >
1084 >        public int size() {
1085 >            checkForComodification();
1086 >            return size;
1087 >        }
1088 >
1089 >        public void add(int index, E element) {
1090 >            rangeCheckForAdd(index);
1091 >            checkForComodification();
1092 >            root.add(offset + index, element);
1093 >            updateSizeAndModCount(1);
1094 >        }
1095 >
1096 >        public E remove(int index) {
1097 >            Objects.checkIndex(index, size);
1098 >            checkForComodification();
1099 >            E result = root.remove(offset + index);
1100 >            updateSizeAndModCount(-1);
1101 >            return result;
1102 >        }
1103 >
1104 >        protected void removeRange(int fromIndex, int toIndex) {
1105 >            checkForComodification();
1106 >            root.removeRange(offset + fromIndex, offset + toIndex);
1107 >            updateSizeAndModCount(fromIndex - toIndex);
1108 >        }
1109 >
1110 >        public boolean addAll(Collection<? extends E> c) {
1111 >            return addAll(this.size, c);
1112 >        }
1113 >
1114 >        public boolean addAll(int index, Collection<? extends E> c) {
1115 >            rangeCheckForAdd(index);
1116 >            int cSize = c.size();
1117 >            if (cSize==0)
1118 >                return false;
1119 >            checkForComodification();
1120 >            root.addAll(offset + index, c);
1121 >            updateSizeAndModCount(cSize);
1122 >            return true;
1123 >        }
1124 >
1125 >        public boolean removeAll(Collection<?> c) {
1126 >            return batchRemove(c, false);
1127 >        }
1128 >
1129 >        public boolean retainAll(Collection<?> c) {
1130 >            return batchRemove(c, true);
1131 >        }
1132 >
1133 >        private boolean batchRemove(Collection<?> c, boolean complement) {
1134 >            checkForComodification();
1135 >            int oldSize = root.size;
1136 >            boolean modified =
1137 >                root.batchRemove(c, complement, offset, offset + size);
1138 >            if (modified)
1139 >                updateSizeAndModCount(root.size - oldSize);
1140 >            return modified;
1141 >        }
1142 >
1143 >        public boolean removeIf(Predicate<? super E> filter) {
1144 >            checkForComodification();
1145 >            int oldSize = root.size;
1146 >            boolean modified = root.removeIf(filter, offset, offset + size);
1147 >            if (modified)
1148 >                updateSizeAndModCount(root.size - oldSize);
1149 >            return modified;
1150 >        }
1151 >
1152 >        public Iterator<E> iterator() {
1153 >            return listIterator();
1154 >        }
1155 >
1156 >        public ListIterator<E> listIterator(int index) {
1157 >            checkForComodification();
1158 >            rangeCheckForAdd(index);
1159 >
1160 >            return new ListIterator<E>() {
1161 >                int cursor = index;
1162 >                int lastRet = -1;
1163 >                int expectedModCount = root.modCount;
1164 >
1165 >                public boolean hasNext() {
1166 >                    return cursor != SubList.this.size;
1167 >                }
1168 >
1169 >                @SuppressWarnings("unchecked")
1170 >                public E next() {
1171 >                    checkForComodification();
1172 >                    int i = cursor;
1173 >                    if (i >= SubList.this.size)
1174 >                        throw new NoSuchElementException();
1175 >                    Object[] elementData = root.elementData;
1176 >                    if (offset + i >= elementData.length)
1177 >                        throw new ConcurrentModificationException();
1178 >                    cursor = i + 1;
1179 >                    return (E) elementData[offset + (lastRet = i)];
1180 >                }
1181 >
1182 >                public boolean hasPrevious() {
1183 >                    return cursor != 0;
1184 >                }
1185 >
1186 >                @SuppressWarnings("unchecked")
1187 >                public E previous() {
1188 >                    checkForComodification();
1189 >                    int i = cursor - 1;
1190 >                    if (i < 0)
1191 >                        throw new NoSuchElementException();
1192 >                    Object[] elementData = root.elementData;
1193 >                    if (offset + i >= elementData.length)
1194 >                        throw new ConcurrentModificationException();
1195 >                    cursor = i;
1196 >                    return (E) elementData[offset + (lastRet = i)];
1197 >                }
1198 >
1199 >                public void forEachRemaining(Consumer<? super E> action) {
1200 >                    Objects.requireNonNull(action);
1201 >                    final int size = SubList.this.size;
1202 >                    int i = cursor;
1203 >                    if (i < size) {
1204 >                        final Object[] es = root.elementData;
1205 >                        if (offset + i >= es.length)
1206 >                            throw new ConcurrentModificationException();
1207 >                        for (; i < size && modCount == expectedModCount; i++)
1208 >                            action.accept(elementAt(es, offset + i));
1209 >                        // update once at end to reduce heap write traffic
1210 >                        cursor = i;
1211 >                        lastRet = i - 1;
1212 >                        checkForComodification();
1213 >                    }
1214 >                }
1215 >
1216 >                public int nextIndex() {
1217 >                    return cursor;
1218 >                }
1219 >
1220 >                public int previousIndex() {
1221 >                    return cursor - 1;
1222 >                }
1223 >
1224 >                public void remove() {
1225 >                    if (lastRet < 0)
1226 >                        throw new IllegalStateException();
1227 >                    checkForComodification();
1228 >
1229 >                    try {
1230 >                        SubList.this.remove(lastRet);
1231 >                        cursor = lastRet;
1232 >                        lastRet = -1;
1233 >                        expectedModCount = root.modCount;
1234 >                    } catch (IndexOutOfBoundsException ex) {
1235 >                        throw new ConcurrentModificationException();
1236 >                    }
1237 >                }
1238 >
1239 >                public void set(E e) {
1240 >                    if (lastRet < 0)
1241 >                        throw new IllegalStateException();
1242 >                    checkForComodification();
1243 >
1244 >                    try {
1245 >                        root.set(offset + lastRet, e);
1246 >                    } catch (IndexOutOfBoundsException ex) {
1247 >                        throw new ConcurrentModificationException();
1248 >                    }
1249 >                }
1250 >
1251 >                public void add(E e) {
1252 >                    checkForComodification();
1253 >
1254 >                    try {
1255 >                        int i = cursor;
1256 >                        SubList.this.add(i, e);
1257 >                        cursor = i + 1;
1258 >                        lastRet = -1;
1259 >                        expectedModCount = root.modCount;
1260 >                    } catch (IndexOutOfBoundsException ex) {
1261 >                        throw new ConcurrentModificationException();
1262 >                    }
1263 >                }
1264 >
1265 >                final void checkForComodification() {
1266 >                    if (root.modCount != expectedModCount)
1267 >                        throw new ConcurrentModificationException();
1268 >                }
1269 >            };
1270 >        }
1271 >
1272 >        public List<E> subList(int fromIndex, int toIndex) {
1273 >            subListRangeCheck(fromIndex, toIndex, size);
1274 >            return new SubList<>(this, fromIndex, toIndex);
1275 >        }
1276 >
1277 >        private void rangeCheckForAdd(int index) {
1278 >            if (index < 0 || index > this.size)
1279 >                throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1280 >        }
1281 >
1282 >        private String outOfBoundsMsg(int index) {
1283 >            return "Index: "+index+", Size: "+this.size;
1284 >        }
1285 >
1286 >        private void checkForComodification() {
1287 >            if (root.modCount != modCount)
1288 >                throw new ConcurrentModificationException();
1289 >        }
1290 >
1291 >        private void updateSizeAndModCount(int sizeChange) {
1292 >            SubList<E> slist = this;
1293 >            do {
1294 >                slist.size += sizeChange;
1295 >                slist.modCount = root.modCount;
1296 >                slist = slist.parent;
1297 >            } while (slist != null);
1298 >        }
1299 >
1300 >        public Spliterator<E> spliterator() {
1301 >            checkForComodification();
1302 >
1303 >            // ArrayListSpliterator not used here due to late-binding
1304 >            return new Spliterator<E>() {
1305 >                private int index = offset; // current index, modified on advance/split
1306 >                private int fence = -1; // -1 until used; then one past last index
1307 >                private int expectedModCount; // initialized when fence set
1308 >
1309 >                private int getFence() { // initialize fence to size on first use
1310 >                    int hi; // (a specialized variant appears in method forEach)
1311 >                    if ((hi = fence) < 0) {
1312 >                        expectedModCount = modCount;
1313 >                        hi = fence = offset + size;
1314 >                    }
1315 >                    return hi;
1316 >                }
1317 >
1318 >                public ArrayList<E>.ArrayListSpliterator trySplit() {
1319 >                    int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1320 >                    // ArrayListSpliterator can be used here as the source is already bound
1321 >                    return (lo >= mid) ? null : // divide range in half unless too small
1322 >                        root.new ArrayListSpliterator(lo, index = mid, expectedModCount);
1323 >                }
1324 >
1325 >                public boolean tryAdvance(Consumer<? super E> action) {
1326 >                    Objects.requireNonNull(action);
1327 >                    int hi = getFence(), i = index;
1328 >                    if (i < hi) {
1329 >                        index = i + 1;
1330 >                        @SuppressWarnings("unchecked") E e = (E)root.elementData[i];
1331 >                        action.accept(e);
1332 >                        if (root.modCount != expectedModCount)
1333 >                            throw new ConcurrentModificationException();
1334 >                        return true;
1335 >                    }
1336 >                    return false;
1337 >                }
1338 >
1339 >                public void forEachRemaining(Consumer<? super E> action) {
1340 >                    Objects.requireNonNull(action);
1341 >                    int i, hi, mc; // hoist accesses and checks from loop
1342 >                    ArrayList<E> lst = root;
1343 >                    Object[] a;
1344 >                    if ((a = lst.elementData) != null) {
1345 >                        if ((hi = fence) < 0) {
1346 >                            mc = modCount;
1347 >                            hi = offset + size;
1348 >                        }
1349 >                        else
1350 >                            mc = expectedModCount;
1351 >                        if ((i = index) >= 0 && (index = hi) <= a.length) {
1352 >                            for (; i < hi; ++i) {
1353 >                                @SuppressWarnings("unchecked") E e = (E) a[i];
1354 >                                action.accept(e);
1355 >                            }
1356 >                            if (lst.modCount == mc)
1357 >                                return;
1358 >                        }
1359 >                    }
1360 >                    throw new ConcurrentModificationException();
1361 >                }
1362 >
1363 >                public long estimateSize() {
1364 >                    return getFence() - index;
1365 >                }
1366 >
1367 >                public int characteristics() {
1368 >                    return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
1369 >                }
1370 >            };
1371 >        }
1372 >    }
1373 >
1374 >    @Override
1375 >    public void forEach(Consumer<? super E> action) {
1376 >        Objects.requireNonNull(action);
1377 >        final int expectedModCount = modCount;
1378 >        final Object[] es = elementData;
1379 >        final int size = this.size;
1380 >        for (int i = 0; modCount == expectedModCount && i < size; i++)
1381 >            action.accept(elementAt(es, i));
1382 >        if (modCount != expectedModCount)
1383 >            throw new ConcurrentModificationException();
1384 >    }
1385 >
1386 >    /**
1387 >     * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
1388 >     * and <em>fail-fast</em> {@link Spliterator} over the elements in this
1389 >     * list.
1390 >     *
1391 >     * <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
1392 >     * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}.
1393 >     * Overriding implementations should document the reporting of additional
1394 >     * characteristic values.
1395 >     *
1396 >     * @return a {@code Spliterator} over the elements in this list
1397 >     * @since 1.8
1398 >     */
1399 >    @Override
1400 >    public Spliterator<E> spliterator() {
1401 >        return new ArrayListSpliterator(0, -1, 0);
1402 >    }
1403 >
1404 >    /** Index-based split-by-two, lazily initialized Spliterator */
1405 >    final class ArrayListSpliterator implements Spliterator<E> {
1406 >
1407 >        /*
1408 >         * If ArrayLists were immutable, or structurally immutable (no
1409 >         * adds, removes, etc), we could implement their spliterators
1410 >         * with Arrays.spliterator. Instead we detect as much
1411 >         * interference during traversal as practical without
1412 >         * sacrificing much performance. We rely primarily on
1413 >         * modCounts. These are not guaranteed to detect concurrency
1414 >         * violations, and are sometimes overly conservative about
1415 >         * within-thread interference, but detect enough problems to
1416 >         * be worthwhile in practice. To carry this out, we (1) lazily
1417 >         * initialize fence and expectedModCount until the latest
1418 >         * point that we need to commit to the state we are checking
1419 >         * against; thus improving precision.  (This doesn't apply to
1420 >         * SubLists, that create spliterators with current non-lazy
1421 >         * values).  (2) We perform only a single
1422 >         * ConcurrentModificationException check at the end of forEach
1423 >         * (the most performance-sensitive method). When using forEach
1424 >         * (as opposed to iterators), we can normally only detect
1425 >         * interference after actions, not before. Further
1426 >         * CME-triggering checks apply to all other possible
1427 >         * violations of assumptions for example null or too-small
1428 >         * elementData array given its size(), that could only have
1429 >         * occurred due to interference.  This allows the inner loop
1430 >         * of forEach to run without any further checks, and
1431 >         * simplifies lambda-resolution. While this does entail a
1432 >         * number of checks, note that in the common case of
1433 >         * list.stream().forEach(a), no checks or other computation
1434 >         * occur anywhere other than inside forEach itself.  The other
1435 >         * less-often-used methods cannot take advantage of most of
1436 >         * these streamlinings.
1437 >         */
1438 >
1439 >        private int index; // current index, modified on advance/split
1440 >        private int fence; // -1 until used; then one past last index
1441 >        private int expectedModCount; // initialized when fence set
1442 >
1443 >        /** Create new spliterator covering the given range */
1444 >        ArrayListSpliterator(int origin, int fence, int expectedModCount) {
1445 >            this.index = origin;
1446 >            this.fence = fence;
1447 >            this.expectedModCount = expectedModCount;
1448 >        }
1449 >
1450 >        private int getFence() { // initialize fence to size on first use
1451 >            int hi; // (a specialized variant appears in method forEach)
1452 >            if ((hi = fence) < 0) {
1453 >                expectedModCount = modCount;
1454 >                hi = fence = size;
1455 >            }
1456 >            return hi;
1457 >        }
1458 >
1459 >        public ArrayListSpliterator trySplit() {
1460 >            int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1461 >            return (lo >= mid) ? null : // divide range in half unless too small
1462 >                new ArrayListSpliterator(lo, index = mid, expectedModCount);
1463 >        }
1464 >
1465 >        public boolean tryAdvance(Consumer<? super E> action) {
1466 >            if (action == null)
1467 >                throw new NullPointerException();
1468 >            int hi = getFence(), i = index;
1469 >            if (i < hi) {
1470 >                index = i + 1;
1471 >                @SuppressWarnings("unchecked") E e = (E)elementData[i];
1472 >                action.accept(e);
1473 >                if (modCount != expectedModCount)
1474 >                    throw new ConcurrentModificationException();
1475 >                return true;
1476 >            }
1477 >            return false;
1478 >        }
1479 >
1480 >        public void forEachRemaining(Consumer<? super E> action) {
1481 >            int i, hi, mc; // hoist accesses and checks from loop
1482 >            Object[] a;
1483 >            if (action == null)
1484 >                throw new NullPointerException();
1485 >            if ((a = elementData) != null) {
1486 >                if ((hi = fence) < 0) {
1487 >                    mc = modCount;
1488 >                    hi = size;
1489 >                }
1490 >                else
1491 >                    mc = expectedModCount;
1492 >                if ((i = index) >= 0 && (index = hi) <= a.length) {
1493 >                    for (; i < hi; ++i) {
1494 >                        @SuppressWarnings("unchecked") E e = (E) a[i];
1495 >                        action.accept(e);
1496 >                    }
1497 >                    if (modCount == mc)
1498 >                        return;
1499 >                }
1500 >            }
1501 >            throw new ConcurrentModificationException();
1502 >        }
1503 >
1504 >        public long estimateSize() {
1505 >            return getFence() - index;
1506 >        }
1507 >
1508 >        public int characteristics() {
1509 >            return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
1510 >        }
1511 >    }
1512 >
1513 >    // A tiny bit set implementation
1514 >
1515 >    private static long[] nBits(int n) {
1516 >        return new long[((n - 1) >> 6) + 1];
1517 >    }
1518 >    private static void setBit(long[] bits, int i) {
1519 >        bits[i >> 6] |= 1L << i;
1520 >    }
1521 >    private static boolean isClear(long[] bits, int i) {
1522 >        return (bits[i >> 6] & (1L << i)) == 0;
1523 >    }
1524 >
1525 >    @Override
1526 >    public boolean removeIf(Predicate<? super E> filter) {
1527 >        return removeIf(filter, 0, size);
1528 >    }
1529 >
1530 >    /**
1531 >     * Removes all elements satisfying the given predicate, from index
1532 >     * i (inclusive) to index end (exclusive).
1533 >     */
1534 >    boolean removeIf(Predicate<? super E> filter, int i, final int end) {
1535 >        Objects.requireNonNull(filter);
1536 >        int expectedModCount = modCount;
1537 >        final Object[] es = elementData;
1538 >        // Optimize for initial run of survivors
1539 >        for (; i < end && !filter.test(elementAt(es, i)); i++)
1540 >            ;
1541 >        // Tolerate predicates that reentrantly access the collection for
1542 >        // read (but writers still get CME), so traverse once to find
1543 >        // elements to delete, a second pass to physically expunge.
1544 >        if (i < end) {
1545 >            final int beg = i;
1546 >            final long[] deathRow = nBits(end - beg);
1547 >            deathRow[0] = 1L;   // set bit 0
1548 >            for (i = beg + 1; i < end; i++)
1549 >                if (filter.test(elementAt(es, i)))
1550 >                    setBit(deathRow, i - beg);
1551 >            if (modCount != expectedModCount)
1552 >                throw new ConcurrentModificationException();
1553 >            expectedModCount++;
1554 >            modCount++;
1555 >            int w = beg;
1556 >            for (i = beg; i < end; i++)
1557 >                if (isClear(deathRow, i - beg))
1558 >                    es[w++] = es[i];
1559 >            shiftTailOverGap(es, w, end);
1560 >            // checkInvariants();
1561 >            return true;
1562 >        } else {
1563 >            if (modCount != expectedModCount)
1564 >                throw new ConcurrentModificationException();
1565 >            // checkInvariants();
1566 >            return false;
1567 >        }
1568 >    }
1569 >
1570 >    @Override
1571 >    public void replaceAll(UnaryOperator<E> operator) {
1572 >        Objects.requireNonNull(operator);
1573 >        final int expectedModCount = modCount;
1574 >        final Object[] es = elementData;
1575 >        final int size = this.size;
1576 >        for (int i = 0; modCount == expectedModCount && i < size; i++)
1577 >            es[i] = operator.apply(elementAt(es, i));
1578 >        if (modCount != expectedModCount)
1579 >            throw new ConcurrentModificationException();
1580 >        modCount++;
1581 >        // checkInvariants();
1582 >    }
1583 >
1584 >    @Override
1585 >    @SuppressWarnings("unchecked")
1586 >    public void sort(Comparator<? super E> c) {
1587 >        final int expectedModCount = modCount;
1588 >        Arrays.sort((E[]) elementData, 0, size, c);
1589 >        if (modCount != expectedModCount)
1590 >            throw new ConcurrentModificationException();
1591 >        modCount++;
1592 >        // checkInvariants();
1593      }
1594  
1595 <    static void subListRangeCheck(int fromIndex, int toIndex, int size) {
1596 <        if (fromIndex < 0)
1597 <            throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
885 <        if (toIndex > size)
886 <            throw new IndexOutOfBoundsException("toIndex = " + toIndex);
887 <        if (fromIndex > toIndex)
888 <            throw new IllegalArgumentException("fromIndex(" + fromIndex +
889 <                                               ") > toIndex(" + toIndex + ")");
890 <    }
891 <
892 <    private class SubList extends AbstractList<E> implements RandomAccess {
893 <        private final AbstractList<E> parent;
894 <        private final int parentOffset;
895 <        private final int offset;
896 <        private int size;
897 <
898 <        SubList(AbstractList<E> parent,
899 <                int offset, int fromIndex, int toIndex) {
900 <            this.parent = parent;
901 <            this.parentOffset = fromIndex;
902 <            this.offset = offset + fromIndex;
903 <            this.size = toIndex - fromIndex;
904 <            this.modCount = ArrayList.this.modCount;
905 <        }
906 <
907 <        public E set(int index, E e) {
908 <            rangeCheck(index);
909 <            checkForComodification();
910 <            E oldValue = ArrayList.this.elementData(offset + index);
911 <            ArrayList.this.elementData[offset + index] = e;
912 <            return oldValue;
913 <        }
914 <
915 <        public E get(int index) {
916 <            rangeCheck(index);
917 <            checkForComodification();
918 <            return ArrayList.this.elementData(offset + index);
919 <        }
920 <
921 <        public int size() {
922 <            checkForComodification();
923 <            return this.size;
924 <        }
925 <
926 <        public void add(int index, E e) {
927 <            rangeCheckForAdd(index);
928 <            checkForComodification();
929 <            parent.add(parentOffset + index, e);
930 <            this.modCount = parent.modCount;
931 <            this.size++;
932 <        }
933 <
934 <        public E remove(int index) {
935 <            rangeCheck(index);
936 <            checkForComodification();
937 <            E result = parent.remove(parentOffset + index);
938 <            this.modCount = parent.modCount;
939 <            this.size--;
940 <            return result;
941 <        }
942 <
943 <        protected void removeRange(int fromIndex, int toIndex) {
944 <            checkForComodification();
945 <            parent.removeRange(parentOffset + fromIndex,
946 <                               parentOffset + toIndex);
947 <            this.modCount = parent.modCount;
948 <            this.size -= toIndex - fromIndex;
949 <        }
950 <
951 <        public boolean addAll(Collection<? extends E> c) {
952 <            return addAll(this.size, c);
953 <        }
954 <
955 <        public boolean addAll(int index, Collection<? extends E> c) {
956 <            rangeCheckForAdd(index);
957 <            int cSize = c.size();
958 <            if (cSize==0)
959 <                return false;
960 <
961 <            checkForComodification();
962 <            parent.addAll(parentOffset + index, c);
963 <            this.modCount = parent.modCount;
964 <            this.size += cSize;
965 <            return true;
966 <        }
967 <
968 <        public Iterator<E> iterator() {
969 <            return listIterator();
970 <        }
971 <
972 <        public ListIterator<E> listIterator(final int index) {
973 <            checkForComodification();
974 <            rangeCheckForAdd(index);
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 <                        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 <                }
1037 <
1038 <                public void set(E e) {
1039 <                    if (lastRet < 0)
1040 <                        throw new IllegalStateException();
1041 <                    checkForComodification();
1042 <
1043 <                    try {
1044 <                        ArrayList.this.set(offset + lastRet, e);
1045 <                    } catch (IndexOutOfBoundsException ex) {
1046 <                        throw new ConcurrentModificationException();
1047 <                    }
1048 <                }
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 List<E> subList(int fromIndex, int toIndex) {
1072 <            subListRangeCheck(fromIndex, toIndex, size);
1073 <            return new SubList(this, offset, fromIndex, toIndex);
1074 <        }
1075 <
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 <        }
1595 >    void checkInvariants() {
1596 >        // assert size >= 0;
1597 >        // assert size == elementData.length || elementData[size] == null;
1598      }
1599   }

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