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Comparing jsr166/src/main/java/util/AbstractList.java (file contents):
Revision 1.5 by jsr166, Mon Dec 5 02:56:59 2005 UTC vs.
Revision 1.19 by jsr166, Sun May 18 23:47:55 2008 UTC

#	Line 1 | Line 1
1		/*
2	<	* %W% %E%
2	>	* Copyright 1997-2007 Sun Microsystems, Inc.  All Rights Reserved.
3	>	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4		*
5	<	* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
6	<	* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
5	>	* This code is free software; you can redistribute it and/or modify it
6	>	* under the terms of the GNU General Public License version 2 only, as
7	>	* published by the Free Software Foundation.  Sun designates this
8	>	* particular file as subject to the "Classpath" exception as provided
9	>	* by Sun in the LICENSE file that accompanied this code.
10	>	*
11	>	* This code is distributed in the hope that it will be useful, but WITHOUT
12	>	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13	>	* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14	>	* version 2 for more details (a copy is included in the LICENSE file that
15	>	* accompanied this code).
16	>	*
17	>	* You should have received a copy of the GNU General Public License version
18	>	* 2 along with this work; if not, write to the Free Software Foundation,
19	>	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20	>	*
21	>	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22	>	* CA 95054 USA or visit www.sun.com if you need additional information or
23	>	* have any questions.
24		*/
25
26		package java.util;
27
28		/**
29	<	* This class provides a skeletal implementation of the <tt>List</tt>
29	>	* This class provides a skeletal implementation of the {@link List}
30		* interface to minimize the effort required to implement this interface
31		* backed by a "random access" data store (such as an array).  For sequential
32	<	* access data (such as a linked list), <tt>AbstractSequentialList</tt> should
33	<	* be used in preference to this class.<p>
32	>	* access data (such as a linked list), {@link AbstractSequentialList} should
33	>	* be used in preference to this class.
34	>	*
35	>	* <p>To implement an unmodifiable list, the programmer needs only to extend
36	>	* this class and provide implementations for the {@link #get(int)} and
37	>	* {@link List#size() size()} methods.
38		*
39	<	* To implement an unmodifiable list, the programmer needs only to extend this
40	<	* class and provide implementations for the <tt>get(int index)</tt> and
41	<	* <tt>size()</tt> methods.<p>
42	<	*
43	<	* To implement a modifiable list, the programmer must additionally override
22	<	* the <tt>set(int index, Object element)</tt> method (which otherwise throws
23	<	* an <tt>UnsupportedOperationException</tt>.  If the list is variable-size
24	<	* the programmer must additionally override the <tt>add(int index, Object
25	<	* element)</tt> and <tt>remove(int index)</tt> methods.<p>
26	<	*
27	<	* The programmer should generally provide a void (no argument) and collection
28	<	* constructor, as per the recommendation in the <tt>Collection</tt> interface
29	<	* specification.<p>
39	>	* <p>To implement a modifiable list, the programmer must additionally
40	>	* override the {@link #set(int, Object) set(int, E)} method (which otherwise
41	>	* throws an {@code UnsupportedOperationException}).  If the list is
42	>	* variable-size the programmer must additionally override the
43	>	* {@link #add(int, Object) add(int, E)} and {@link #remove(int)} methods.
44		*
45	<	* Unlike the other abstract collection implementations, the programmer does
45	>	* <p>The programmer should generally provide a void (no argument) and collection
46	>	* constructor, as per the recommendation in the {@link Collection} interface
47	>	* specification.
48	>	*
49	>	* <p>Unlike the other abstract collection implementations, the programmer does
50		* <i>not</i> have to provide an iterator implementation; the iterator and
51		* list iterator are implemented by this class, on top of the "random access"
52	<	* methods: <tt>get(int index)</tt>, <tt>set(int index, E element)</tt>,
53	<	* <tt>add(int index, E element)</tt> and <tt>remove(int index)</tt>.<p>
52	>	* methods:
53	>	* {@link #get(int)},
54	>	* {@link #set(int, Object) set(int, E)},
55	>	* {@link #add(int, Object) add(int, E)} and
56	>	* {@link #remove(int)}.
57		*
58	<	* The documentation for each non-abstract methods in this class describes its
58	>	* <p>The documentation for each non-abstract method in this class describes its
59		* implementation in detail.  Each of these methods may be overridden if the
60	<	* collection being implemented admits a more efficient implementation.<p>
60	>	* collection being implemented admits a more efficient implementation.
61		*
62	<	* This class is a member of the
63	<	* <a href="{@docRoot}/../guide/collections/index.html">
62	>	* <p>This class is a member of the
63	>	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
64		* Java Collections Framework</a>.
65		*
66		* @author  Josh Bloch
67		* @author  Neal Gafter
68	<	* @version 1.37, 01/18/03
48	<	* @see Collection
49	<	* @see List
50	<	* @see AbstractSequentialList
51	<	* @see AbstractCollection
68	>	* @version %I%, %G%
69		* @since 1.2
70		*/
71
#	Line 71 | Line 88 | public abstract class AbstractList<E> ex
88		* classes should clearly specify in their documentation any restrictions
89		* on what elements may be added.
90		*
91	<	* <p>This implementation calls <tt>add(size(), e)</tt>.
91	>	* <p>This implementation calls {@code add(size(), e)}.
92		*
93		* <p>Note that this implementation throws an
94	<	* <tt>UnsupportedOperationException</tt> unless <tt>add(int, Object)</tt>
95	<	* is overridden.
94	>	* {@code UnsupportedOperationException} unless
95	>	* {@link #add(int, Object) add(int, E)} is overridden.
96		*
97		* @param e element to be appended to this list
98	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
99	<	* @throws UnsupportedOperationException if the <tt>add</tt> operation
98	>	* @return {@code true} (as specified by {@link Collection#add})
99	>	* @throws UnsupportedOperationException if the {@code add} operation
100		*         is not supported by this list
101		* @throws ClassCastException if the class of the specified element
102		*         prevents it from being added to this list
#	Line 89 | Line 106 | public abstract class AbstractList<E> ex
106		*         prevents it from being added to this list
107		*/
108		public boolean add(E e) {
109	<	add(size(), e);
110	<	return true;
109	>	add(size(), e);
110	>	return true;
111		}
112
113		/**
#	Line 104 | Line 121 | public abstract class AbstractList<E> ex
121		* {@inheritDoc}
122		*
123		* <p>This implementation always throws an
124	<	* <tt>UnsupportedOperationException</tt>.
124	>	* {@code UnsupportedOperationException}.
125		*
126		* @throws UnsupportedOperationException {@inheritDoc}
127		* @throws ClassCastException            {@inheritDoc}
#	Line 113 | Line 130 | public abstract class AbstractList<E> ex
130		* @throws IndexOutOfBoundsException     {@inheritDoc}
131		*/
132		public E set(int index, E element) {
133	<	throw new UnsupportedOperationException();
133	>	throw new UnsupportedOperationException();
134		}
135
136		/**
137		* {@inheritDoc}
138		*
139		* <p>This implementation always throws an
140	<	* <tt>UnsupportedOperationException</tt>.
140	>	* {@code UnsupportedOperationException}.
141		*
142		* @throws UnsupportedOperationException {@inheritDoc}
143		* @throws ClassCastException            {@inheritDoc}
#	Line 129 | Line 146 | public abstract class AbstractList<E> ex
146		* @throws IndexOutOfBoundsException     {@inheritDoc}
147		*/
148		public void add(int index, E element) {
149	<	throw new UnsupportedOperationException();
149	>	throw new UnsupportedOperationException();
150		}
151
152		/**
153		* {@inheritDoc}
154		*
155		* <p>This implementation always throws an
156	<	* <tt>UnsupportedOperationException</tt>.
156	>	* {@code UnsupportedOperationException}.
157		*
158		* @throws UnsupportedOperationException {@inheritDoc}
159		* @throws IndexOutOfBoundsException     {@inheritDoc}
160		*/
161		public E remove(int index) {
162	<	throw new UnsupportedOperationException();
162	>	throw new UnsupportedOperationException();
163		}
164
165
#	Line 152 | Line 169 | public abstract class AbstractList<E> ex
169		* {@inheritDoc}
170		*
171		* <p>This implementation first gets a list iterator (with
172	<	* <tt>listIterator()</tt>).  Then, it iterates over the list until the
172	>	* {@code listIterator()}).  Then, it iterates over the list until the
173		* specified element is found or the end of the list is reached.
174		*
175		* @throws ClassCastException   {@inheritDoc}
176		* @throws NullPointerException {@inheritDoc}
177		*/
178		public int indexOf(Object o) {
179	<	ListIterator<E> e = listIterator();
180	<	if (o==null) {
181	<	while (e.hasNext())
182	<	if (e.next()==null)
183	<	return e.previousIndex();
184	<	} else {
185	<	while (e.hasNext())
186	<	if (o.equals(e.next()))
187	<	return e.previousIndex();
188	<	}
189	<	return -1;
179	>	ListIterator<E> e = listIterator();
180	>	if (o==null) {
181	>	while (e.hasNext())
182	>	if (e.next()==null)
183	>	return e.previousIndex();
184	>	} else {
185	>	while (e.hasNext())
186	>	if (o.equals(e.next()))
187	>	return e.previousIndex();
188	>	}
189	>	return -1;
190		}
191
192		/**
193		* {@inheritDoc}
194		*
195		* <p>This implementation first gets a list iterator that points to the end
196	<	* of the list (with <tt>listIterator(size())</tt>).  Then, it iterates
196	>	* of the list (with {@code listIterator(size())}).  Then, it iterates
197		* backwards over the list until the specified element is found, or the
198		* beginning of the list is reached.
199		*
#	Line 184 | Line 201 | public abstract class AbstractList<E> ex
201		* @throws NullPointerException {@inheritDoc}
202		*/
203		public int lastIndexOf(Object o) {
204	<	ListIterator<E> e = listIterator(size());
205	<	if (o==null) {
206	<	while (e.hasPrevious())
207	<	if (e.previous()==null)
208	<	return e.nextIndex();
209	<	} else {
210	<	while (e.hasPrevious())
211	<	if (o.equals(e.previous()))
212	<	return e.nextIndex();
213	<	}
214	<	return -1;
204	>	ListIterator<E> e = listIterator(size());
205	>	if (o==null) {
206	>	while (e.hasPrevious())
207	>	if (e.previous()==null)
208	>	return e.nextIndex();
209	>	} else {
210	>	while (e.hasPrevious())
211	>	if (o.equals(e.previous()))
212	>	return e.nextIndex();
213	>	}
214	>	return -1;
215		}
216
217
#	Line 204 | Line 221 | public abstract class AbstractList<E> ex
221		* Removes all of the elements from this list (optional operation).
222		* The list will be empty after this call returns.
223		*
224	<	* <p>This implementation calls <tt>removeRange(0, size())</tt>.
224	>	* <p>This implementation calls {@code removeRange(0, size())}.
225		*
226		* <p>Note that this implementation throws an
227	<	* <tt>UnsupportedOperationException</tt> unless <tt>remove(int
228	<	* index)</tt> or <tt>removeRange(int fromIndex, int toIndex)</tt> is
227	>	* {@code UnsupportedOperationException} unless {@code remove(int
228	>	* index)} or {@code removeRange(int fromIndex, int toIndex)} is
229		* overridden.
230		*
231	<	* @throws UnsupportedOperationException if the <tt>clear</tt> operation
231	>	* @throws UnsupportedOperationException if the {@code clear} operation
232		*         is not supported by this list
233		*/
234		public void clear() {
#	Line 221 | Line 238 | public abstract class AbstractList<E> ex
238		/**
239		* {@inheritDoc}
240		*
241	<	* <p>This implementation gets an iterator over the specified collection and
242	<	* iterates over it, inserting the elements obtained from the iterator
243	<	* into this list at the appropriate position, one at a time, using
244	<	* <tt>add(int, Object)</tt>.  Many implementations will override this
245	<	* method for efficiency.
241	>	* <p>This implementation gets an iterator over the specified collection
242	>	* and iterates over it, inserting the elements obtained from the
243	>	* iterator into this list at the appropriate position, one at a time,
244	>	* using {@code add(int, E)}.
245	>	* Many implementations will override this method for efficiency.
246		*
247		* <p>Note that this implementation throws an
248	<	* <tt>UnsupportedOperationException</tt> unless <tt>add(int, Object)</tt>
249	<	* is overridden.
248	>	* {@code UnsupportedOperationException} unless
249	>	* {@link #add(int, Object) add(int, E)} is overridden.
250		*
251		* @throws UnsupportedOperationException {@inheritDoc}
252		* @throws ClassCastException            {@inheritDoc}
#	Line 238 | Line 255 | public abstract class AbstractList<E> ex
255		* @throws IndexOutOfBoundsException     {@inheritDoc}
256		*/
257		public boolean addAll(int index, Collection<? extends E> c) {
258	<	boolean modified = false;
259	<	Iterator<? extends E> e = c.iterator();
260	<	while (e.hasNext()) {
261	<	add(index++, e.next());
262	<	modified = true;
263	<	}
264	<	return modified;
258	>	rangeCheckForAdd(index);
259	>	boolean modified = false;
260	>	Iterator<? extends E> e = c.iterator();
261	>	while (e.hasNext()) {
262	>	add(index++, e.next());
263	>	modified = true;
264	>	}
265	>	return modified;
266		}
267
268
269		// Iterators
270
271		/**
272	<	* Returns an iterator over the elements in this list in proper
255	<	* sequence. <p>
272	>	* Returns an iterator over the elements in this list in proper sequence.
273		*
274	<	* This implementation returns a straightforward implementation of the
275	<	* iterator interface, relying on the backing list's <tt>size()</tt>,
276	<	* <tt>get(int)</tt>, and <tt>remove(int)</tt> methods.<p>
260	<	*
261	<	* Note that the iterator returned by this method will throw an
262	<	* <tt>UnsupportedOperationException</tt> in response to its
263	<	* <tt>remove</tt> method unless the list's <tt>remove(int)</tt> method is
264	<	* overridden.<p>
265	<	*
266	<	* This implementation can be made to throw runtime exceptions in the face
267	<	* of concurrent modification, as described in the specification for the
268	<	* (protected) <tt>modCount</tt> field.
274	>	* <p>This implementation returns a straightforward implementation of the
275	>	* iterator interface, relying on the backing list's {@code size()},
276	>	* {@code get(int)}, and {@code remove(int)} methods.
277		*
278	<	* @return an iterator over the elements in this list in proper sequence
278	>	* <p>Note that the iterator returned by this method will throw an
279	>	* {@link UnsupportedOperationException} in response to its
280	>	* {@code remove} method unless the list's {@code remove(int)} method is
281	>	* overridden.
282		*
283	<	* @see #modCount
283	>	* <p>This implementation can be made to throw runtime exceptions in the
284	>	* face of concurrent modification, as described in the specification
285	>	* for the (protected) {@link #modCount} field.
286	>	*
287	>	* @return an iterator over the elements in this list in proper sequence
288		*/
289		public Iterator<E> iterator() {
290	<	return new Itr();
290	>	return new Itr();
291		}
292
293		/**
294		* {@inheritDoc}
295		*
296	<	* <p>This implementation returns <tt>listIterator(0)</tt>.
296	>	* <p>This implementation returns {@code listIterator(0)}.
297		*
298		* @see #listIterator(int)
299		*/
300		public ListIterator<E> listIterator() {
301	<	return listIterator(0);
301	>	return listIterator(0);
302		}
303
304		/**
305		* {@inheritDoc}
306		*
307		* <p>This implementation returns a straightforward implementation of the
308	<	* <tt>ListIterator</tt> interface that extends the implementation of the
309	<	* <tt>Iterator</tt> interface returned by the <tt>iterator()</tt> method.
310	<	* The <tt>ListIterator</tt> implementation relies on the backing list's
311	<	* <tt>get(int)</tt>, <tt>set(int, Object)</tt>, <tt>add(int, Object)</tt>
312	<	* and <tt>remove(int)</tt> methods.
308	>	* {@code ListIterator} interface that extends the implementation of the
309	>	* {@code Iterator} interface returned by the {@code iterator()} method.
310	>	* The {@code ListIterator} implementation relies on the backing list's
311	>	* {@code get(int)}, {@code set(int, E)}, {@code add(int, E)}
312	>	* and {@code remove(int)} methods.
313		*
314		* <p>Note that the list iterator returned by this implementation will
315	<	* throw an <tt>UnsupportedOperationException</tt> in response to its
316	<	* <tt>remove</tt>, <tt>set</tt> and <tt>add</tt> methods unless the
317	<	* list's <tt>remove(int)</tt>, <tt>set(int, Object)</tt>, and
318	<	* <tt>add(int, Object)</tt> methods are overridden.
315	>	* throw an {@link UnsupportedOperationException} in response to its
316	>	* {@code remove}, {@code set} and {@code add} methods unless the
317	>	* list's {@code remove(int)}, {@code set(int, E)}, and
318	>	* {@code add(int, E)} methods are overridden.
319		*
320		* <p>This implementation can be made to throw runtime exceptions in the
321		* face of concurrent modification, as described in the specification for
322	<	* the (protected) <tt>modCount</tt> field.
322	>	* the (protected) {@link #modCount} field.
323		*
324		* @throws IndexOutOfBoundsException {@inheritDoc}
310	–	*
311	–	* @see #modCount
325		*/
326		public ListIterator<E> listIterator(final int index) {
327	<	if (index<0 || index>size())
315	<	throw new IndexOutOfBoundsException("Index: "+index);
327	>	rangeCheckForAdd(index);
328
329	<	return new ListItr(index);
329	>	return new ListItr(index);
330		}
331
332		private class Itr implements Iterator<E> {
333	<	/**
334	<	* Index of element to be returned by subsequent call to next.
335	<	*/
336	<	int cursor = 0;
337	<
338	<	/**
339	<	* Index of element returned by most recent call to next or
340	<	* previous.  Reset to -1 if this element is deleted by a call
341	<	* to remove.
342	<	*/
343	<	int lastRet = -1;
344	<
345	<	/**
346	<	* The modCount value that the iterator believes that the backing
347	<	* List should have.  If this expectation is violated, the iterator
348	<	* has detected concurrent modification.
349	<	*/
350	<	int expectedModCount = modCount;
333	>	/**
334	>	* Index of element to be returned by subsequent call to next.
335	>	*/
336	>	int cursor = 0;
337	>
338	>	/**
339	>	* Index of element returned by most recent call to next or
340	>	* previous.  Reset to -1 if this element is deleted by a call
341	>	* to remove.
342	>	*/
343	>	int lastRet = -1;
344	>
345	>	/**
346	>	* The modCount value that the iterator believes that the backing
347	>	* List should have.  If this expectation is violated, the iterator
348	>	* has detected concurrent modification.
349	>	*/
350	>	int expectedModCount = modCount;
351
352	<	public boolean hasNext() {
352	>	public boolean hasNext() {
353		return cursor != size();
354	<	}
354	>	}
355
356	<	public E next() {
356	>	public E next() {
357	>	checkForComodification();
358		try {
359		int i = cursor;
360		E next = get(i);
361		lastRet = i;
362		cursor = i + 1;
363		return next;
364	<	} catch (IndexOutOfBoundsException ex) {
364	>	} catch (IndexOutOfBoundsException e) {
365	>	checkForComodification();
366		throw new NoSuchElementException();
367	<	} finally {
368	<	if (expectedModCount != modCount)
369	<	throw new ConcurrentModificationException();
370	<	}
371	<	}
372	<
373	<	public void remove() {
374	<	if (lastRet == -1)
375	<	throw new IllegalStateException();
376	<	if (expectedModCount != modCount)
377	<	throw new ConcurrentModificationException();
378	<	try {
379	<	AbstractList.this.remove(lastRet);
380	<	if (lastRet < cursor)
381	<	cursor--;
382	<	lastRet = -1;
383	<	expectedModCount = modCount;
384	<	} catch (IndexOutOfBoundsException e) {
385	<	throw new ConcurrentModificationException();
386	<	}
387	<	}
367	>	}
368	>	}
369	>
370	>	public void remove() {
371	>	if (lastRet < 0)
372	>	throw new IllegalStateException();
373	>	checkForComodification();
374	>
375	>	try {
376	>	AbstractList.this.remove(lastRet);
377	>	if (lastRet < cursor)
378	>	cursor--;
379	>	lastRet = -1;
380	>	expectedModCount = modCount;
381	>	} catch (IndexOutOfBoundsException e) {
382	>	throw new ConcurrentModificationException();
383	>	}
384	>	}
385	>
386	>	final void checkForComodification() {
387	>	if (modCount != expectedModCount)
388	>	throw new ConcurrentModificationException();
389	>	}
390		}
391	<
391	>
392		private class ListItr extends Itr implements ListIterator<E> {
393	<	ListItr(int index) {
394	<	cursor = index;
395	<	}
396	<
397	<	public boolean hasPrevious() {
398	<	return cursor != 0;
399	<	}
384	<
385	<	public int nextIndex() {
386	<	return cursor;
387	<	}
388	<
389	<	public int previousIndex() {
390	<	return cursor - 1;
391	<	}
393	>	ListItr(int index) {
394	>	cursor = index;
395	>	}
396	>
397	>	public boolean hasPrevious() {
398	>	return cursor != 0;
399	>	}
400
401		public E previous() {
402	+	checkForComodification();
403		try {
404		int i = cursor - 1;
405	<	E prev = get(i);
406	<	lastRet = i;
407	<	cursor = i;
408	<	return prev;
409	<	} catch (IndexOutOfBoundsException ex) {
405	>	E previous = get(i);
406	>	lastRet = cursor = i;
407	>	return previous;
408	>	} catch (IndexOutOfBoundsException e) {
409	>	checkForComodification();
410		throw new NoSuchElementException();
402	–	} finally {
403	–	if (expectedModCount != modCount)
404	–	throw new ConcurrentModificationException();
411		}
412		}
413
414	<	public void set(E e) {
415	<	if (lastRet == -1)
416	<	throw new IllegalStateException();
417	<	if (expectedModCount != modCount)
418	<	throw new ConcurrentModificationException();
419	<	try {
420	<	AbstractList.this.set(lastRet, e);
415	<	expectedModCount = modCount;
416	<	} catch (IndexOutOfBoundsException ex) {
417	<	throw new ConcurrentModificationException();
418	<	}
419	<	}
414	>	public int nextIndex() {
415	>	return cursor;
416	>	}
417	>
418	>	public int previousIndex() {
419	>	return cursor-1;
420	>	}
421
422	<	public void add(E e) {
423	<	if (expectedModCount != modCount)
422	>	public void set(E e) {
423	>	if (lastRet < 0)
424	>	throw new IllegalStateException();
425	>	checkForComodification();
426	>
427	>	try {
428	>	AbstractList.this.set(lastRet, e);
429	>	expectedModCount = modCount;
430	>	} catch (IndexOutOfBoundsException ex) {
431		throw new ConcurrentModificationException();
432	<	try {
432	>	}
433	>	}
434	>
435	>	public void add(E e) {
436	>	checkForComodification();
437	>
438	>	try {
439		int i = cursor;
440	<	AbstractList.this.add(i, e);
440	>	AbstractList.this.add(i, e);
441	>	lastRet = -1;
442		cursor = i + 1;
443	<	lastRet = -1;
444	<	expectedModCount = modCount;
445	<	} catch (IndexOutOfBoundsException ex) {
446	<	throw new ConcurrentModificationException();
447	<	}
433	<	}
443	>	expectedModCount = modCount;
444	>	} catch (IndexOutOfBoundsException ex) {
445	>	throw new ConcurrentModificationException();
446	>	}
447	>	}
448		}
449
450		/**
451		* {@inheritDoc}
452		*
453		* <p>This implementation returns a list that subclasses
454	<	* <tt>AbstractList</tt>.  The subclass stores, in private fields, the
454	>	* {@code AbstractList}.  The subclass stores, in private fields, the
455		* offset of the subList within the backing list, the size of the subList
456		* (which can change over its lifetime), and the expected
457	<	* <tt>modCount</tt> value of the backing list.  There are two variants
458	<	* of the subclass, one of which implements <tt>RandomAccess</tt>.
459	<	* If this list implements <tt>RandomAccess</tt> the returned list will
460	<	* be an instance of the subclass that implements <tt>RandomAccess</tt>.
461	<	*
462	<	* <p>The subclass's <tt>set(int, Object)</tt>, <tt>get(int)</tt>,
463	<	* <tt>add(int, Object)</tt>, <tt>remove(int)</tt>, <tt>addAll(int,
464	<	* Collection)</tt> and <tt>removeRange(int, int)</tt> methods all
457	>	* {@code modCount} value of the backing list.  There are two variants
458	>	* of the subclass, one of which implements {@code RandomAccess}.
459	>	* If this list implements {@code RandomAccess} the returned list will
460	>	* be an instance of the subclass that implements {@code RandomAccess}.
461	>	*
462	>	* <p>The subclass's {@code set(int, E)}, {@code get(int)},
463	>	* {@code add(int, E)}, {@code remove(int)}, {@code addAll(int,
464	>	* Collection)} and {@code removeRange(int, int)} methods all
465		* delegate to the corresponding methods on the backing abstract list,
466		* after bounds-checking the index and adjusting for the offset.  The
467	<	* <tt>addAll(Collection c)</tt> method merely returns <tt>addAll(size,
468	<	* c)</tt>.
467	>	* {@code addAll(Collection c)} method merely returns {@code addAll(size,
468	>	* c)}.
469		*
470	<	* <p>The <tt>listIterator(int)</tt> method returns a "wrapper object"
470	>	* <p>The {@code listIterator(int)} method returns a "wrapper object"
471		* over a list iterator on the backing list, which is created with the
472	<	* corresponding method on the backing list.  The <tt>iterator</tt> method
473	<	* merely returns <tt>listIterator()</tt>, and the <tt>size</tt> method
474	<	* merely returns the subclass's <tt>size</tt> field.
472	>	* corresponding method on the backing list.  The {@code iterator} method
473	>	* merely returns {@code listIterator()}, and the {@code size} method
474	>	* merely returns the subclass's {@code size} field.
475		*
476	<	* <p>All methods first check to see if the actual <tt>modCount</tt> of
476	>	* <p>All methods first check to see if the actual {@code modCount} of
477		* the backing list is equal to its expected value, and throw a
478	<	* <tt>ConcurrentModificationException</tt> if it is not.
478	>	* {@code ConcurrentModificationException} if it is not.
479		*
480	<	* @throws IndexOutOfBoundsException endpoint index value out of range
481	<	*         <tt>(fromIndex &lt; 0 || toIndex &gt; size)</tt>
480	>	* @throws IndexOutOfBoundsException if an endpoint index value is out of range
481	>	*         {@code (fromIndex < 0 || toIndex > size)}
482		* @throws IllegalArgumentException if the endpoint indices are out of order
483	<	*         <tt>(fromIndex &gt; toIndex)</tt>
483	>	*         {@code (fromIndex > toIndex)}
484		*/
485		public List<E> subList(int fromIndex, int toIndex) {
486		return (this instanceof RandomAccess ?
#	Line 478 | Line 492 | public abstract class AbstractList<E> ex
492
493		/**
494		* Compares the specified object with this list for equality.  Returns
495	<	* <tt>true</tt> if and only if the specified object is also a list, both
495	>	* {@code true} if and only if the specified object is also a list, both
496		* lists have the same size, and all corresponding pairs of elements in
497	<	* the two lists are <i>equal</i>.  (Two elements <tt>e1</tt> and
498	<	* <tt>e2</tt> are <i>equal</i> if <tt>(e1==null ? e2==null :
499	<	* e1.equals(e2))</tt>.)  In other words, two lists are defined to be
497	>	* the two lists are <i>equal</i>.  (Two elements {@code e1} and
498	>	* {@code e2} are <i>equal</i> if {@code (e1==null ? e2==null :
499	>	* e1.equals(e2))}.)  In other words, two lists are defined to be
500		* equal if they contain the same elements in the same order.<p>
501		*
502		* This implementation first checks if the specified object is this
503	<	* list. If so, it returns <tt>true</tt>; if not, it checks if the
504	<	* specified object is a list. If not, it returns <tt>false</tt>; if so,
503	>	* list. If so, it returns {@code true}; if not, it checks if the
504	>	* specified object is a list. If not, it returns {@code false}; if so,
505		* it iterates over both lists, comparing corresponding pairs of elements.
506	<	* If any comparison returns <tt>false</tt>, this method returns
507	<	* <tt>false</tt>.  If either iterator runs out of elements before the
508	<	* other it returns <tt>false</tt> (as the lists are of unequal length);
509	<	* otherwise it returns <tt>true</tt> when the iterations complete.
506	>	* If any comparison returns {@code false}, this method returns
507	>	* {@code false}.  If either iterator runs out of elements before the
508	>	* other it returns {@code false} (as the lists are of unequal length);
509	>	* otherwise it returns {@code true} when the iterations complete.
510		*
511		* @param o the object to be compared for equality with this list
512	<	* @return <tt>true</tt> if the specified object is equal to this list
512	>	* @return {@code true} if the specified object is equal to this list
513		*/
514		public boolean equals(Object o) {
515	<	if (o == this)
516	<	return true;
517	<	if (!(o instanceof List))
518	<	return false;
519	<
520	<	ListIterator<E> e1 = listIterator();
521	<	ListIterator e2 = ((List) o).listIterator();
522	<	while(e1.hasNext() && e2.hasNext()) {
523	<	E o1 = e1.next();
524	<	Object o2 = e2.next();
525	<	if (!(o1==null ? o2==null : o1.equals(o2)))
526	<	return false;
527	<	}
528	<	return !(e1.hasNext() || e2.hasNext());
515	>	if (o == this)
516	>	return true;
517	>	if (!(o instanceof List))
518	>	return false;
519	>
520	>	ListIterator<E> e1 = listIterator();
521	>	ListIterator e2 = ((List) o).listIterator();
522	>	while(e1.hasNext() && e2.hasNext()) {
523	>	E o1 = e1.next();
524	>	Object o2 = e2.next();
525	>	if (!(o1==null ? o2==null : o1.equals(o2)))
526	>	return false;
527	>	}
528	>	return !(e1.hasNext() || e2.hasNext());
529		}
530
531		/**
532	<	* Returns the hash code value for this list. <p>
532	>	* Returns the hash code value for this list.
533		*
534	<	* This implementation uses exactly the code that is used to define the
534	>	* <p>This implementation uses exactly the code that is used to define the
535		* list hash function in the documentation for the {@link List#hashCode}
536		* method.
537		*
538		* @return the hash code value for this list
539		*/
540		public int hashCode() {
541	<	int hashCode = 1;
542	<	Iterator<E> i = iterator();
543	<	while (i.hasNext()) {
544	<	E obj = i.next();
531	<	hashCode = 31*hashCode + (obj==null ? 0 : obj.hashCode());
532	<	}
533	<	return hashCode;
541	>	int hashCode = 1;
542	>	for (E e : this)
543	>	hashCode = 31*hashCode + (e==null ? 0 : e.hashCode());
544	>	return hashCode;
545		}
546
547		/**
548		* Removes from this list all of the elements whose index is between
549	<	* <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive.
549	>	* {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
550		* Shifts any succeeding elements to the left (reduces their index).
551	<	* This call shortens the ArrayList by <tt>(toIndex - fromIndex)</tt>
552	<	* elements.  (If <tt>toIndex==fromIndex</tt>, this operation has no
542	<	* effect.)<p>
551	>	* This call shortens the list by {@code (toIndex - fromIndex)} elements.
552	>	* (If {@code toIndex==fromIndex}, this operation has no effect.)
553		*
554	<	* This method is called by the <tt>clear</tt> operation on this list
554	>	* <p>This method is called by the {@code clear} operation on this list
555		* and its subLists.  Overriding this method to take advantage of
556		* the internals of the list implementation can <i>substantially</i>
557	<	* improve the performance of the <tt>clear</tt> operation on this list
558	<	* and its subLists.<p>
557	>	* improve the performance of the {@code clear} operation on this list
558	>	* and its subLists.
559		*
560	<	* This implementation gets a list iterator positioned before
561	<	* <tt>fromIndex</tt>, and repeatedly calls <tt>ListIterator.next</tt>
562	<	* followed by <tt>ListIterator.remove</tt> until the entire range has
563	<	* been removed.  <b>Note: if <tt>ListIterator.remove</tt> requires linear
560	>	* <p>This implementation gets a list iterator positioned before
561	>	* {@code fromIndex}, and repeatedly calls {@code ListIterator.next}
562	>	* followed by {@code ListIterator.remove} until the entire range has
563	>	* been removed.  <b>Note: if {@code ListIterator.remove} requires linear
564		* time, this implementation requires quadratic time.</b>
565		*
566		* @param fromIndex index of first element to be removed
#	Line 568 | Line 578 | public abstract class AbstractList<E> ex
578		* The number of times this list has been <i>structurally modified</i>.
579		* Structural modifications are those that change the size of the
580		* list, or otherwise perturb it in such a fashion that iterations in
581	<	* progress may yield incorrect results.<p>
581	>	* progress may yield incorrect results.
582		*
583	<	* This field is used by the iterator and list iterator implementation
584	<	* returned by the <tt>iterator</tt> and <tt>listIterator</tt> methods.
583	>	* <p>This field is used by the iterator and list iterator implementation
584	>	* returned by the {@code iterator} and {@code listIterator} methods.
585		* If the value of this field changes unexpectedly, the iterator (or list
586	<	* iterator) will throw a <tt>ConcurrentModificationException</tt> in
587	<	* response to the <tt>next</tt>, <tt>remove</tt>, <tt>previous</tt>,
588	<	* <tt>set</tt> or <tt>add</tt> operations.  This provides
586	>	* iterator) will throw a {@code ConcurrentModificationException} in
587	>	* response to the {@code next}, {@code remove}, {@code previous},
588	>	* {@code set} or {@code add} operations.  This provides
589		* <i>fail-fast</i> behavior, rather than non-deterministic behavior in
590	<	* the face of concurrent modification during iteration.<p>
590	>	* the face of concurrent modification during iteration.
591		*
592	<	* <b>Use of this field by subclasses is optional.</b> If a subclass
592	>	* <p><b>Use of this field by subclasses is optional.</b> If a subclass
593		* wishes to provide fail-fast iterators (and list iterators), then it
594	<	* merely has to increment this field in its <tt>add(int, Object)</tt> and
595	<	* <tt>remove(int)</tt> methods (and any other methods that it overrides
594	>	* merely has to increment this field in its {@code add(int, E)} and
595	>	* {@code remove(int)} methods (and any other methods that it overrides
596		* that result in structural modifications to the list).  A single call to
597	<	* <tt>add(int, Object)</tt> or <tt>remove(int)</tt> must add no more than
597	>	* {@code add(int, E)} or {@code remove(int)} must add no more than
598		* one to this field, or the iterators (and list iterators) will throw
599	<	* bogus <tt>ConcurrentModificationExceptions</tt>.  If an implementation
599	>	* bogus {@code ConcurrentModificationExceptions}.  If an implementation
600		* does not wish to provide fail-fast iterators, this field may be
601		* ignored.
602		*/
603		protected transient int modCount = 0;
604	+
605	+	private void rangeCheckForAdd(int index) {
606	+	if (index < 0 || index > size())
607	+	throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
608	+	}
609	+
610	+	private String outOfBoundsMsg(int index) {
611	+	return "Index: "+index+", Size: "+size();
612	+	}
613		}
614
615		class SubList<E> extends AbstractList<E> {
616	<	private AbstractList<E> l;
617	<	private int offset;
616	>	private final AbstractList<E> l;
617	>	private final int offset;
618		private int size;
600	–	private int expectedModCount;
619
620		SubList(AbstractList<E> list, int fromIndex, int toIndex) {
621		if (fromIndex < 0)
#	Line 610 | Line 628 | class SubList<E> extends AbstractList<E>
628		l = list;
629		offset = fromIndex;
630		size = toIndex - fromIndex;
631	<	expectedModCount = l.modCount;
631	>	this.modCount = l.modCount;
632		}
633
634		public E set(int index, E element) {
#	Line 631 | Line 649 | class SubList<E> extends AbstractList<E>
649		}
650
651		public void add(int index, E element) {
652	<	if (index<0 || index>size)
635	<	throw new IndexOutOfBoundsException();
652	>	rangeCheckForAdd(index);
653		checkForComodification();
654		l.add(index+offset, element);
655	<	expectedModCount = l.modCount;
655	>	this.modCount = l.modCount;
656		size++;
640	–	modCount++;
657		}
658
659		public E remove(int index) {
660		rangeCheck(index);
661		checkForComodification();
662		E result = l.remove(index+offset);
663	<	expectedModCount = l.modCount;
663	>	this.modCount = l.modCount;
664		size--;
649	–	modCount++;
665		return result;
666		}
667
668		protected void removeRange(int fromIndex, int toIndex) {
669		checkForComodification();
670		l.removeRange(fromIndex+offset, toIndex+offset);
671	<	expectedModCount = l.modCount;
671	>	this.modCount = l.modCount;
672		size -= (toIndex-fromIndex);
658	–	modCount++;
673		}
674
675		public boolean addAll(Collection<? extends E> c) {
#	Line 663 | Line 677 | class SubList<E> extends AbstractList<E>
677		}
678
679		public boolean addAll(int index, Collection<? extends E> c) {
680	<	if (index<0 || index>size)
667	<	throw new IndexOutOfBoundsException(
668	<	"Index: "+index+", Size: "+size);
680	>	rangeCheckForAdd(index);
681		int cSize = c.size();
682		if (cSize==0)
683		return false;
684
685		checkForComodification();
686		l.addAll(offset+index, c);
687	<	expectedModCount = l.modCount;
687	>	this.modCount = l.modCount;
688		size += cSize;
677	–	modCount++;
689		return true;
690		}
691
#	Line 684 | Line 695 | class SubList<E> extends AbstractList<E>
695
696		public ListIterator<E> listIterator(final int index) {
697		checkForComodification();
698	<	if (index<0 || index>size)
688	<	throw new IndexOutOfBoundsException(
689	<	"Index: "+index+", Size: "+size);
698	>	rangeCheckForAdd(index);
699
700		return new ListIterator<E>() {
701	<	private ListIterator<E> i = l.listIterator(index+offset);
701	>	private final ListIterator<E> i = l.listIterator(index+offset);
702
703		public boolean hasNext() {
704		return nextIndex() < size;
#	Line 723 | Line 732 | class SubList<E> extends AbstractList<E>
732
733		public void remove() {
734		i.remove();
735	<	expectedModCount = l.modCount;
735	>	SubList.this.modCount = l.modCount;
736		size--;
728	–	modCount++;
737		}
738
739		public void set(E e) {
#	Line 734 | Line 742 | class SubList<E> extends AbstractList<E>
742
743		public void add(E e) {
744		i.add(e);
745	<	expectedModCount = l.modCount;
745	>	SubList.this.modCount = l.modCount;
746		size++;
739	–	modCount++;
747		}
748		};
749		}
#	Line 746 | Line 753 | class SubList<E> extends AbstractList<E>
753		}
754
755		private void rangeCheck(int index) {
756	<	if (index<0 || index>=size)
757	<	throw new IndexOutOfBoundsException("Index: "+index+
758	<	",Size: "+size);
756	>	if (index < 0 || index >= size)
757	>	throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
758	>	}
759	>
760	>	private void rangeCheckForAdd(int index) {
761	>	if (index < 0 || index > size)
762	>	throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
763	>	}
764	>
765	>	private String outOfBoundsMsg(int index) {
766	>	return "Index: "+index+", Size: "+size;
767		}
768
769		private void checkForComodification() {
770	<	if (l.modCount != expectedModCount)
770	>	if (this.modCount != l.modCount)
771		throw new ConcurrentModificationException();
772		}
773		}

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