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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 1.47 by jsr166, Mon Dec 5 00:08:01 2016 UTC

#	Line 1 | Line 1
1		/*
2	<	* %W% %E%
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	<	* 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.  Oracle designates this
8	>	* particular file as subject to the "Classpath" exception as provided
9	>	* by Oracle in the LICENSE file that accompanied this code.
10	>	*
11	>	* This code is distributed in the hope that it will be useful, but WITHOUT
12	>	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13	>	* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14	>	* version 2 for more details (a copy is included in the LICENSE file that
15	>	* accompanied this code).
16	>	*
17	>	* You should have received a copy of the GNU General Public License version
18	>	* 2 along with this work; if not, write to the Free Software Foundation,
19	>	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20	>	*
21	>	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22	>	* or visit www.oracle.com if you need additional information or have any
23	>	* questions.
24		*/
25
26		package java.util;
27	<	import java.util.*; // for javadoc (till 6280605 is fixed)
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.)<p>
38	>	* {@code Vector}, except that it is unsynchronized.)
39		*
40	<	* 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.<p>
45	>	* to that for the {@code LinkedList} implementation.
46		*
47	<	* 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.<p>
52	>	* time cost.
53		*
54	<	* 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 49 | Line 70 | import java.util.*; // for javadoc (till
70		* unsynchronized access to the list:<pre>
71		*   List list = Collections.synchronizedList(new ArrayList(...));</pre>
72		*
73	<	* <p>The iterators returned by this class's <tt>iterator</tt> and
74	<	* <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is
75	<	* structurally modified at any time after the iterator is created, in any way
76	<	* except through the iterator's own <tt>remove</tt> or <tt>add</tt> methods,
77	<	* the iterator will throw a {@link ConcurrentModificationException}.  Thus, in
78	<	* the face of concurrent modification, the iterator fails quickly and cleanly,
79	<	* rather than risking arbitrary, non-deterministic behavior at an undetermined
80	<	* time in the future.<p>
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
77	>	* created, in any way except through the iterator's own
78	>	* {@link ListIterator#remove() remove} or
79	>	* {@link ListIterator#add(Object) add} methods, the iterator will throw a
80	>	* {@link ConcurrentModificationException}.  Thus, in the face of
81	>	* concurrent modification, the iterator fails quickly and cleanly, rather
82	>	* than risking arbitrary, non-deterministic behavior at an undetermined
83	>	* time in the future.
84		*
85	<	* Note that the fail-fast behavior of an iterator cannot be guaranteed
85	>	* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
86		* as it is, generally speaking, impossible to make any hard guarantees in the
87		* presence of unsynchronized concurrent modification.  Fail-fast iterators
88	<	* throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
88	>	* throw {@code ConcurrentModificationException} on a best-effort basis.
89		* Therefore, it would be wrong to write a program that depended on this
90	<	* exception for its correctness: <i>the fail-fast behavior of iterators
91	<	* should be used only to detect bugs.</i><p>
90	>	* exception for its correctness:  <i>the fail-fast behavior of iterators
91	>	* should be used only to detect bugs.</i>
92		*
93	<	* This class is a member of the
94	<	* <a href="{@docRoot}/../guide/collections/index.html">
93	>	* <p>This class is a member of the
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
79	<	* @see     Vector
101	>	* @see     Collection
102	>	* @see     List
103	>	* @see     LinkedList
104	>	* @see     Vector
105		* @since   1.2
106		*/
82	–
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 101 | 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
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		/**
170		* Constructs a list containing the elements of the specified
171		* collection, in the order they are returned by the collection's
172	<	* iterator.  The <tt>ArrayList</tt> instance has an initial capacity of
127	<	* 110% the size of the specified collection.
172	>	* iterator.
173		*
174		* @param c the collection whose elements are to be placed into this list
175		* @throws NullPointerException if the specified collection is null
176		*/
177		public ArrayList(Collection<? extends E> c) {
178	<	int size = c.size();
179	<	// 10% for growth
180	<	int cap = ((size/10)+1)*11;
181	<	if (cap > 0) {
182	<	Object[] a = new Object[cap];
183	<	a[size] = a[size+1] = UNALLOCATED;
184	<	Object[] b = c.toArray(a);
185	<	if (b[size] == null && b[size+1] == UNALLOCATED) {
186	<	b[size+1] = null;
187	<	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);
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
158	–	private final static Object UNALLOCATED = new Object();
159	–
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
210		*/
211		public void ensureCapacity(int minCapacity) {
212	<	modCount++;
213	<	if (minCapacity > elementData.length)
214	<	growArray(minCapacity);
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	<	* Increases the capacity of the array.
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 void growArray(int minCapacity) {
254	<	if (minCapacity < 0) throw new OutOfMemoryError(); // int overflow
255	<	int oldCapacity = elementData.length;
256	<	// Double size if small; else grow by 50%
257	<	int newCapacity = ((oldCapacity < 64)?
258	<	(oldCapacity * 2):
259	<	((oldCapacity * 3)/2));
260	<	if (newCapacity < minCapacity)
261	<	newCapacity = minCapacity;
262	<	elementData = Arrays.copyOf(elementData, newCapacity);
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 206 | 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	<	ArrayList<E> v = (ArrayList<E>) 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();
363	<	}
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 318 | 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 331 | Line 405 | public class ArrayList<E> extends Abstra
405		*         this list
406		* @throws NullPointerException if the specified array is null
407		*/
408	+	@SuppressWarnings("unchecked")
409		public <T> T[] toArray(T[] a) {
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 343 | Line 418 | public class ArrayList<E> extends Abstra
418
419		// Positional Access Operations
420
421	<	/**
422	<	* Throws an appropriate exception for indexing errors.
423	<	*/
424	<	private static void rangeException(int i, int s) {
425	<	throw new IndexOutOfBoundsException("Index: " + i + ", Size: " + s);
421	>	@SuppressWarnings("unchecked")
422	>	E elementData(int 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 358 | Line 436 | public class ArrayList<E> extends Abstra
436		* @throws IndexOutOfBoundsException {@inheritDoc}
437		*/
438		public E get(int index) {
439	<	if (index >= size)
440	<	rangeException(index, size);
363	<	return (E)elementData[index];
439	>	Objects.checkIndex(index, size);
440	>	return elementData(index);
441		}
442
443		/**
#	Line 373 | Line 450 | public class ArrayList<E> extends Abstra
450		* @throws IndexOutOfBoundsException {@inheritDoc}
451		*/
452		public E set(int index, E element) {
453	<	if (index >= size)
454	<	rangeException(index, size);
453	>	Objects.checkIndex(index, size);
454	>	E oldValue = elementData(index);
455	>	elementData[index] = element;
456	>	return oldValue;
457	>	}
458
459	<	E oldValue = (E) 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	<	++modCount;
479	<	int s = size;
480	<	if (s >= elementData.length)
394	<	growArray(s + 1);
395	<	elementData[s] = e;
396	<	size = s + 1;
397	<	return true;
478	>	modCount++;
479	>	add(e, elementData, size);
480	>	return true;
481		}
482
483		/**
#	Line 407 | Line 490 | public class ArrayList<E> extends Abstra
490		* @throws IndexOutOfBoundsException {@inheritDoc}
491		*/
492		public void add(int index, E element) {
493	<	int s = size;
494	<	if (index > s || index < 0)
495	<	rangeException(index, s);
496	<	++modCount;
497	<	if (s >= elementData.length)
498	<	growArray(s + 1);
499	<	System.arraycopy(elementData, index,
500	<	elementData, index + 1, s - index);
501	<	elementData[index] = element;
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 429 | Line 514 | public class ArrayList<E> extends Abstra
514		* @throws IndexOutOfBoundsException {@inheritDoc}
515		*/
516		public E remove(int index) {
517	<	int s = size - 1;
518	<	if (index < 0 || index > s)
519	<	rangeException(index, size);
520	<	modCount++;
521	<	E oldValue = (E)elementData[index];
522	<	int numMoved = s - index;
523	<	if (numMoved > 0)
524	<	System.arraycopy(elementData, index + 1,
525	<	elementData, index, numMoved);
526	<	elementData[s] = null; // forget removed element
527	<	size = s;
528	<	return oldValue;
517	>	Objects.checkIndex(index, size);
518	>
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; // clear to let GC do its work
527	>
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 (o.equals(elementData[index])) {
555	<	fastRemove(index);
556	<	return true;
557	<	}
548	>	if (elementData[index] == null) {
549	>	fastRemove(index);
550	>	return true;
551	>	}
552	>	} else {
553	>	for (int index = 0; index < size; index++)
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 483 | 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 491 | 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++)
498	<	elementData[i] = null;
499	<
500	<	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 510 | 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 533 | 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	<	if (index > size || index < 0)
542	<	throw new IndexOutOfBoundsException(
543	<	"Index: " + index + ", Size: " + size);
544	<
545	<	Object[] a = c.toArray();
546	<	int numNew = a.length;
547	<	ensureCapacity(size + numNew);  // Increments modCount
548	<
549	<	int numMoved = size - index;
550	<	if (numMoved > 0)
551	<	System.arraycopy(elementData, index, elementData, index + numNew,
552	<	numMoved);
631	>	rangeCheckForAdd(index);
632
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		/**
655		* Removes from this list all of the elements whose index is between
656	<	* <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive.
656	>	* {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
657		* Shifts any succeeding elements to the left (reduces their index).
658	<	* This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements.
659	<	* (If <tt>toIndex==fromIndex</tt>, this operation has no effect.)
658	>	* This call shortens the list by {@code (toIndex - fromIndex)} elements.
659	>	* (If {@code toIndex==fromIndex}, this operation has no effect.)
660		*
661	<	* @param fromIndex index of first element to be removed
662	<	* @param toIndex index after last element to be removed
663	<	* @throws IndexOutOfBoundsException if fromIndex or toIndex out of
664	<	*              range (fromIndex &lt; 0 || fromIndex &gt;= size() || toIndex
665	<	*              &gt; size() || toIndex &lt; fromIndex)
661	>	* @throws IndexOutOfBoundsException if {@code fromIndex} or
662	>	*         {@code toIndex} is out of range
663	>	*         ({@code fromIndex < 0 ||
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);
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	<	// Let gc do its work
678	<	int newSize = size - (toIndex-fromIndex);
679	<	while (size != newSize)
680	<	elementData[--size] = null;
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	<	* Save the state of the <tt>ArrayList</tt> instance to a stream (that
686	<	* is, serialize it).
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));
690	>	}
691	>
692	>	/**
693	>	* Constructs an IndexOutOfBoundsException detail message.
694	>	* Of the many possible refactorings of the error handling code,
695	>	* this "outlining" performs best with both server and client VMs.
696	>	*/
697	>	private String outOfBoundsMsg(int index) {
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	>	/**
709	>	* Removes from this list all of its elements that are contained in the
710	>	* specified collection.
711	>	*
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
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
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, 0, size);
725	>	}
726	>
727	>	/**
728	>	* Retains only the elements in this list that are contained in the
729	>	* specified collection.  In other words, removes from this list all
730	>	* of its elements that are not contained in the specified collection.
731	>	*
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
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
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, 0, size);
745	>	}
746	>
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	>	* 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		}
608	–
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 {
617	–	// Read in size, and any hidden stuff
618	–	s.defaultReadObject();
816
817	<	// Read in array length and allocate array
818	<	int arrayLength = s.readInt();
622	<	Object[] a = elementData = new Object[arrayLength];
817	>	// Read in size, and any hidden stuff
818	>	s.defaultReadObject();
819
820	<	// Read in all elements in the proper order.
821	<	for (int i=0; i<size; i++)
626	<	a[i] = s.readObject();
627	<	}
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		/**
841	<	* Returns a list-iterator of the elements in this list (in proper
841	>	* Returns a list iterator over the elements in this list (in proper
842		* sequence), starting at the specified position in the list.
843	<	* Obeys the general contract of <tt>List.listIterator(int)</tt>.<p>
843	>	* The specified index indicates the first element that would be
844	>	* returned by an initial call to {@link ListIterator#next next}.
845	>	* An initial call to {@link ListIterator#previous previous} would
846	>	* return the element with the specified index minus one.
847	>	*
848	>	* <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
849		*
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
850		* @throws IndexOutOfBoundsException {@inheritDoc}
649	–	* @see List#listIterator(int)
851		*/
852		public ListIterator<E> listIterator(int index) {
853	<	if (index < 0 || index > size)
854	<	throw new IndexOutOfBoundsException("Index: "+index);
855	<	return new ArrayListIterator(index);
853	>	rangeCheckForAdd(index);
854	>	return new ListItr(index);
855	>	}
856	>
857	>	/**
858	>	* Returns a list iterator over the elements in this list (in proper
859	>	* sequence).
860	>	*
861	>	* <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
862	>	*
863	>	* @see #listIterator(int)
864	>	*/
865	>	public ListIterator<E> listIterator() {
866	>	return new ListItr(0);
867		}
868
869		/**
870		* Returns an iterator over the elements in this list in proper sequence.
871		*
872	+	* <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
873	+	*
874		* @return an iterator over the elements in this list in proper sequence
875		*/
876		public Iterator<E> iterator() {
877	<	return new ArrayListIterator(0);
877	>	return new Itr();
878		}
879
880		/**
881	<	* A streamlined version of AbstractList.Itr
881	>	* An optimized version of AbstractList.Itr
882		*/
883	<	final class ArrayListIterator implements ListIterator<E> {
884	<	int cursor;           // index of next element to return;
885	<	int lastRet;          // index of last element, or -1 if no such
886	<	int expectedModCount; // to check for CME
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;
887	>
888	>	// prevent creating a synthetic constructor
889	>	Itr() {}
890	>
891	>	public boolean hasNext() {
892	>	return cursor != size;
893	>	}
894	>
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();
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	>	@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	<	ArrayListIterator(int index) {
942	<	cursor = index;
943	<	lastRet = -1;
944	<	expectedModCount = modCount;
945	<	}
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 hasNext() {
957	<	return cursor < size;
958	<	}
956	>	public boolean hasPrevious() {
957	>	return cursor != 0;
958	>	}
959
960	<	public boolean hasPrevious() {
961	<	return cursor > 0;
962	<	}
960	>	public int nextIndex() {
961	>	return cursor;
962	>	}
963
964	<	public int nextIndex() {
965	<	return cursor;
966	<	}
964	>	public int previousIndex() {
965	>	return cursor - 1;
966	>	}
967
968	<	public int previousIndex() {
969	<	return cursor - 1;
970	<	}
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];
979	>	}
980
981	<	public E next() {
982	<	if (expectedModCount == modCount) {
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	>	}
992	>
993	>	public void add(E e) {
994	>	checkForComodification();
995	>
996	>	try {
997		int i = cursor;
998	<	if (i < size) {
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	>	/**
1009	>	* Returns a view of the portion of this list between the specified
1010	>	* {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.  (If
1011	>	* {@code fromIndex} and {@code toIndex} are equal, the returned list is
1012	>	* empty.)  The returned list is backed by this list, so non-structural
1013	>	* changes in the returned list are reflected in this list, and vice-versa.
1014	>	* The returned list supports all of the optional list operations.
1015	>	*
1016	>	* <p>This method eliminates the need for explicit range operations (of
1017	>	* the sort that commonly exist for arrays).  Any operation that expects
1018	>	* a list can be used as a range operation by passing a subList view
1019	>	* instead of a whole list.  For example, the following idiom
1020	>	* removes a range of elements from a list:
1021	>	* <pre>
1022	>	*      list.subList(from, to).clear();
1023	>	* </pre>
1024	>	* Similar idioms may be constructed for {@link #indexOf(Object)} and
1025	>	* {@link #lastIndexOf(Object)}, and all of the algorithms in the
1026	>	* {@link Collections} class can be applied to a subList.
1027	>	*
1028	>	* <p>The semantics of the list returned by this method become undefined if
1029	>	* the backing list (i.e., this list) is <i>structurally modified</i> in
1030	>	* any way other than via the returned list.  (Structural modifications are
1031	>	* those that change the size of this list, or otherwise perturb it in such
1032	>	* a fashion that iterations in progress may yield incorrect results.)
1033	>	*
1034	>	* @throws IndexOutOfBoundsException {@inheritDoc}
1035	>	* @throws IllegalArgumentException {@inheritDoc}
1036	>	*/
1037	>	public List<E> subList(int fromIndex, int 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	<	E e = (E)elementData[i];
1246	<	lastRet = i;
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	<	return e;
1259	<	} catch (IndexOutOfBoundsException fallthrough) {
1258	>	lastRet = -1;
1259	>	expectedModCount = root.modCount;
1260	>	} catch (IndexOutOfBoundsException ex) {
1261	>	throw new ConcurrentModificationException();
1262		}
1263		}
1264	<	}
1265	<	// Prefer reporting CME if applicable on failures
1266	<	if (expectedModCount == modCount)
1267	<	throw new NoSuchElementException();
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	<	}
1384	>	}
1385
1386	<	public E previous() {
1387	<	if (expectedModCount == modCount) {
1388	<	int i = cursor - 1;
1389	<	if (i < size) {
1390	<	try {
1391	<	E e = (E)elementData[i];
1392	<	lastRet = i;
1393	<	cursor = i;
1394	<	return e;
1395	<	} catch (IndexOutOfBoundsException fallthrough) {
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		}
728	–	if (expectedModCount == modCount)
729	–	throw new NoSuchElementException();
1501		throw new ConcurrentModificationException();
1502		}
1503
1504	<	public void remove() {
1505	<	if (lastRet < 0)
1506	<	throw new IllegalStateException();
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	<	ArrayList.this.remove(lastRet);
1554	<	if (lastRet < cursor)
1555	<	cursor--;
1556	<	lastRet = -1;
1557	<	expectedModCount = modCount;
1558	<	}
1559	<
1560	<	public void set(E e) {
1561	<	if (lastRet < 0)
1562	<	throw new IllegalStateException();
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	<	ArrayList.this.set(lastRet, e);
1566	<	expectedModCount = modCount;
1567	<	}
1565	>	// checkInvariants();
1566	>	return false;
1567	>	}
1568	>	}
1569
1570	<	public void add(E e) {
1571	<	if (modCount != expectedModCount)
1572	<	throw new ConcurrentModificationException();
1573	<	ArrayList.this.add(cursor++, e);
1574	<	lastRet = -1;
1575	<	expectedModCount = modCount;
1576	<	}
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	+	void checkInvariants() {
1596	+	// assert size >= 0;
1597	+	// assert size == elementData.length || elementData[size] == null;
1598	+	}
1599		}

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