1 |
|
/* |
2 |
< |
* %W% %E% |
2 |
> |
* Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved. |
3 |
> |
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 |
|
* |
5 |
< |
* Copyright 2005 Sun Microsystems, Inc. All rights reserved. |
6 |
< |
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
5 |
> |
* This code is free software; you can redistribute it and/or modify it |
6 |
> |
* under the terms of the GNU General Public License version 2 only, as |
7 |
> |
* published by the Free Software Foundation. Sun designates this |
8 |
> |
* particular file as subject to the "Classpath" exception as provided |
9 |
> |
* by Sun in the LICENSE file that accompanied this code. |
10 |
> |
* |
11 |
> |
* This code is distributed in the hope that it will be useful, but WITHOUT |
12 |
> |
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
13 |
> |
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
14 |
> |
* version 2 for more details (a copy is included in the LICENSE file that |
15 |
> |
* accompanied this code). |
16 |
> |
* |
17 |
> |
* You should have received a copy of the GNU General Public License version |
18 |
> |
* 2 along with this work; if not, write to the Free Software Foundation, |
19 |
> |
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
20 |
> |
* |
21 |
> |
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
22 |
> |
* CA 95054 USA or visit www.sun.com if you need additional information or |
23 |
> |
* have any questions. |
24 |
|
*/ |
25 |
|
|
26 |
|
package java.util; |
43 |
|
* list. Operations that index into the list will traverse the list from |
44 |
|
* the beginning or the end, whichever is closer to the specified index.<p> |
45 |
|
* |
46 |
< |
* <b>Note that this implementation is not synchronized.</b> If multiple |
47 |
< |
* threads access a list concurrently, and at least one of the threads |
48 |
< |
* modifies the list structurally, it <i>must</i> be synchronized |
49 |
< |
* externally. (A structural modification is any operation that adds or |
50 |
< |
* deletes one or more elements; merely setting the value of an element is not |
51 |
< |
* a structural modification.) This is typically accomplished by |
52 |
< |
* synchronizing on some object that naturally encapsulates the list. If no |
53 |
< |
* such object exists, the list should be "wrapped" using the |
54 |
< |
* Collections.synchronizedList method. This is best done at creation time, |
55 |
< |
* to prevent accidental unsynchronized access to the list: <pre> |
56 |
< |
* List list = Collections.synchronizedList(new LinkedList(...)); |
57 |
< |
* </pre> |
46 |
> |
* <p><strong>Note that this implementation is not synchronized.</strong> |
47 |
> |
* If multiple threads access a linked list concurrently, and at least |
48 |
> |
* one of the threads modifies the list structurally, it <i>must</i> be |
49 |
> |
* synchronized externally. (A structural modification is any operation |
50 |
> |
* that adds or deletes one or more elements; merely setting the value of |
51 |
> |
* an element is not a structural modification.) This is typically |
52 |
> |
* accomplished by synchronizing on some object that naturally |
53 |
> |
* encapsulates the list. |
54 |
> |
* |
55 |
> |
* If no such object exists, the list should be "wrapped" using the |
56 |
> |
* {@link Collections#synchronizedList Collections.synchronizedList} |
57 |
> |
* method. This is best done at creation time, to prevent accidental |
58 |
> |
* unsynchronized access to the list:<pre> |
59 |
> |
* List list = Collections.synchronizedList(new LinkedList(...));</pre> |
60 |
|
* |
61 |
|
* <p>The iterators returned by this class's <tt>iterator</tt> and |
62 |
|
* <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is |
77 |
|
* should be used only to detect bugs.</i> |
78 |
|
* |
79 |
|
* <p>This class is a member of the |
80 |
< |
* <a href="{@docRoot}/../guide/collections/index.html"> |
80 |
> |
* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
81 |
|
* Java Collections Framework</a>. |
82 |
|
* |
83 |
|
* @author Josh Bloch |
84 |
|
* @version %I%, %G% |
85 |
< |
* @see List |
86 |
< |
* @see ArrayList |
87 |
< |
* @see Vector |
68 |
< |
* @see Collections#synchronizedList(List) |
85 |
> |
* @see List |
86 |
> |
* @see ArrayList |
87 |
> |
* @see Vector |
88 |
|
* @since 1.2 |
89 |
|
* @param <E> the type of elements held in this collection |
90 |
|
*/ |
108 |
|
* collection, in the order they are returned by the collection's |
109 |
|
* iterator. |
110 |
|
* |
111 |
< |
* @param c the collection whose elements are to be placed into this list. |
112 |
< |
* @throws NullPointerException if the specified collection is null. |
111 |
> |
* @param c the collection whose elements are to be placed into this list |
112 |
> |
* @throws NullPointerException if the specified collection is null |
113 |
|
*/ |
114 |
< |
public LinkedList(Collection<? extends E> c) { |
115 |
< |
this(); |
116 |
< |
addAll(c); |
117 |
< |
} |
114 |
> |
public LinkedList(Collection<? extends E> c) { |
115 |
> |
this(); |
116 |
> |
addAll(c); |
117 |
> |
} |
118 |
|
|
119 |
|
/** |
120 |
|
* Returns the first element in this list. |
121 |
|
* |
122 |
< |
* @return the first element in this list. |
123 |
< |
* @throws NoSuchElementException if this list is empty. |
122 |
> |
* @return the first element in this list |
123 |
> |
* @throws NoSuchElementException if this list is empty |
124 |
|
*/ |
125 |
|
public E getFirst() { |
126 |
< |
if (size==0) |
127 |
< |
throw new NoSuchElementException(); |
126 |
> |
if (size==0) |
127 |
> |
throw new NoSuchElementException(); |
128 |
|
|
129 |
< |
return header.next.element; |
129 |
> |
return header.next.element; |
130 |
|
} |
131 |
|
|
132 |
|
/** |
133 |
|
* Returns the last element in this list. |
134 |
|
* |
135 |
< |
* @return the last element in this list. |
136 |
< |
* @throws NoSuchElementException if this list is empty. |
135 |
> |
* @return the last element in this list |
136 |
> |
* @throws NoSuchElementException if this list is empty |
137 |
|
*/ |
138 |
|
public E getLast() { |
139 |
< |
if (size==0) |
140 |
< |
throw new NoSuchElementException(); |
139 |
> |
if (size==0) |
140 |
> |
throw new NoSuchElementException(); |
141 |
|
|
142 |
< |
return header.previous.element; |
142 |
> |
return header.previous.element; |
143 |
|
} |
144 |
|
|
145 |
|
/** |
146 |
|
* Removes and returns the first element from this list. |
147 |
|
* |
148 |
< |
* @return the first element from this list. |
149 |
< |
* @throws NoSuchElementException if this list is empty. |
148 |
> |
* @return the first element from this list |
149 |
> |
* @throws NoSuchElementException if this list is empty |
150 |
|
*/ |
151 |
|
public E removeFirst() { |
152 |
< |
return remove(header.next); |
152 |
> |
return remove(header.next); |
153 |
|
} |
154 |
|
|
155 |
|
/** |
156 |
|
* Removes and returns the last element from this list. |
157 |
|
* |
158 |
< |
* @return the last element from this list. |
159 |
< |
* @throws NoSuchElementException if this list is empty. |
158 |
> |
* @return the last element from this list |
159 |
> |
* @throws NoSuchElementException if this list is empty |
160 |
|
*/ |
161 |
|
public E removeLast() { |
162 |
< |
return remove(header.previous); |
162 |
> |
return remove(header.previous); |
163 |
|
} |
164 |
|
|
165 |
|
/** |
166 |
< |
* Inserts the given element at the beginning of this list. |
166 |
> |
* Inserts the specified element at the beginning of this list. |
167 |
|
* |
168 |
< |
* @param e the element to be inserted at the beginning of this list. |
168 |
> |
* @param e the element to add |
169 |
|
*/ |
170 |
|
public void addFirst(E e) { |
171 |
< |
addBefore(e, header.next); |
171 |
> |
addBefore(e, header.next); |
172 |
|
} |
173 |
|
|
174 |
|
/** |
175 |
< |
* Appends the given element to the end of this list. (Identical in |
176 |
< |
* function to the <tt>add</tt> method; included only for consistency.) |
175 |
> |
* Appends the specified element to the end of this list. |
176 |
> |
* |
177 |
> |
* <p>This method is equivalent to {@link #add}. |
178 |
|
* |
179 |
< |
* @param e the element to be inserted at the end of this list. |
179 |
> |
* @param e the element to add |
180 |
|
*/ |
181 |
|
public void addLast(E e) { |
182 |
< |
addBefore(e, header); |
182 |
> |
addBefore(e, header); |
183 |
|
} |
184 |
|
|
185 |
|
/** |
186 |
|
* Returns <tt>true</tt> if this list contains the specified element. |
187 |
|
* More formally, returns <tt>true</tt> if and only if this list contains |
188 |
< |
* at least one element <tt>e</tt> such that <tt>(o==null ? e==null |
189 |
< |
* : o.equals(e))</tt>. |
188 |
> |
* at least one element <tt>e</tt> such that |
189 |
> |
* <tt>(o==null ? e==null : o.equals(e))</tt>. |
190 |
|
* |
191 |
< |
* @param o element whose presence in this list is to be tested. |
192 |
< |
* @return <tt>true</tt> if this list contains the specified element. |
191 |
> |
* @param o element whose presence in this list is to be tested |
192 |
> |
* @return <tt>true</tt> if this list contains the specified element |
193 |
|
*/ |
194 |
|
public boolean contains(Object o) { |
195 |
|
return indexOf(o) != -1; |
198 |
|
/** |
199 |
|
* Returns the number of elements in this list. |
200 |
|
* |
201 |
< |
* @return the number of elements in this list. |
201 |
> |
* @return the number of elements in this list |
202 |
|
*/ |
203 |
|
public int size() { |
204 |
< |
return size; |
204 |
> |
return size; |
205 |
|
} |
206 |
|
|
207 |
|
/** |
208 |
|
* Appends the specified element to the end of this list. |
209 |
|
* |
210 |
< |
* @param e element to be appended to this list. |
211 |
< |
* @return <tt>true</tt> (as per the general contract of |
212 |
< |
* <tt>Collection.add</tt>). |
210 |
> |
* <p>This method is equivalent to {@link #addLast}. |
211 |
> |
* |
212 |
> |
* @param e element to be appended to this list |
213 |
> |
* @return <tt>true</tt> (as specified by {@link Collection#add}) |
214 |
|
*/ |
215 |
|
public boolean add(E e) { |
216 |
< |
addBefore(e, header); |
216 |
> |
addBefore(e, header); |
217 |
|
return true; |
218 |
|
} |
219 |
|
|
220 |
|
/** |
221 |
< |
* Removes the first occurrence of the specified element in this list. If |
222 |
< |
* the list does not contain the element, it is unchanged. More formally, |
223 |
< |
* removes the element with the lowest index <tt>i</tt> such that |
224 |
< |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt> (if such an |
225 |
< |
* element exists). |
221 |
> |
* Removes the first occurrence of the specified element from this list, |
222 |
> |
* if it is present. If this list does not contain the element, it is |
223 |
> |
* unchanged. More formally, removes the element with the lowest index |
224 |
> |
* <tt>i</tt> such that |
225 |
> |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt> |
226 |
> |
* (if such an element exists). Returns <tt>true</tt> if this list |
227 |
> |
* contained the specified element (or equivalently, if this list |
228 |
> |
* changed as a result of the call). |
229 |
|
* |
230 |
< |
* @param o element to be removed from this list, if present. |
231 |
< |
* @return <tt>true</tt> if the list contained the specified element. |
230 |
> |
* @param o element to be removed from this list, if present |
231 |
> |
* @return <tt>true</tt> if this list contained the specified element |
232 |
|
*/ |
233 |
|
public boolean remove(Object o) { |
234 |
|
if (o==null) { |
254 |
|
* this list, in the order that they are returned by the specified |
255 |
|
* collection's iterator. The behavior of this operation is undefined if |
256 |
|
* the specified collection is modified while the operation is in |
257 |
< |
* progress. (This implies that the behavior of this call is undefined if |
258 |
< |
* the specified Collection is this list, and this list is nonempty.) |
257 |
> |
* progress. (Note that this will occur if the specified collection is |
258 |
> |
* this list, and it's nonempty.) |
259 |
|
* |
260 |
< |
* @param c the elements to be inserted into this list. |
261 |
< |
* @return <tt>true</tt> if this list changed as a result of the call. |
262 |
< |
* @throws NullPointerException if the specified collection is null. |
260 |
> |
* @param c collection containing elements to be added to this list |
261 |
> |
* @return <tt>true</tt> if this list changed as a result of the call |
262 |
> |
* @throws NullPointerException if the specified collection is null |
263 |
|
*/ |
264 |
|
public boolean addAll(Collection<? extends E> c) { |
265 |
|
return addAll(size, c); |
273 |
|
* in the list in the order that they are returned by the |
274 |
|
* specified collection's iterator. |
275 |
|
* |
276 |
< |
* @param index index at which to insert first element |
277 |
< |
* from the specified collection. |
278 |
< |
* @param c elements to be inserted into this list. |
279 |
< |
* @return <tt>true</tt> if this list changed as a result of the call. |
280 |
< |
* @throws IndexOutOfBoundsException if the index is out of range |
281 |
< |
* (<tt>index < 0 || index > size()</tt>). |
258 |
< |
* @throws NullPointerException if the specified collection is null. |
276 |
> |
* @param index index at which to insert the first element |
277 |
> |
* from the specified collection |
278 |
> |
* @param c collection containing elements to be added to this list |
279 |
> |
* @return <tt>true</tt> if this list changed as a result of the call |
280 |
> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
281 |
> |
* @throws NullPointerException if the specified collection is null |
282 |
|
*/ |
283 |
|
public boolean addAll(int index, Collection<? extends E> c) { |
284 |
|
if (index < 0 || index > size) |
288 |
|
int numNew = a.length; |
289 |
|
if (numNew==0) |
290 |
|
return false; |
291 |
< |
modCount++; |
291 |
> |
modCount++; |
292 |
|
|
293 |
|
Entry<E> successor = (index==size ? header : entry(index)); |
294 |
|
Entry<E> predecessor = successor.previous; |
295 |
< |
for (int i=0; i<numNew; i++) { |
295 |
> |
for (int i=0; i<numNew; i++) { |
296 |
|
Entry<E> e = new Entry<E>((E)a[i], successor, predecessor); |
297 |
|
predecessor.next = e; |
298 |
|
predecessor = e; |
316 |
|
} |
317 |
|
header.next = header.previous = header; |
318 |
|
size = 0; |
319 |
< |
modCount++; |
319 |
> |
modCount++; |
320 |
|
} |
321 |
|
|
322 |
|
|
325 |
|
/** |
326 |
|
* Returns the element at the specified position in this list. |
327 |
|
* |
328 |
< |
* @param index index of element to return. |
329 |
< |
* @return the element at the specified position in this list. |
330 |
< |
* |
308 |
< |
* @throws IndexOutOfBoundsException if the index is out of range |
309 |
< |
* (<tt>index < 0 || index > size()</tt>). |
328 |
> |
* @param index index of the element to return |
329 |
> |
* @return the element at the specified position in this list |
330 |
> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
331 |
|
*/ |
332 |
|
public E get(int index) { |
333 |
|
return entry(index).element; |
337 |
|
* Replaces the element at the specified position in this list with the |
338 |
|
* specified element. |
339 |
|
* |
340 |
< |
* @param index index of element to replace. |
341 |
< |
* @param element element to be stored at the specified position. |
342 |
< |
* @return the element previously at the specified position. |
343 |
< |
* @throws IndexOutOfBoundsException if the index is out of range |
323 |
< |
* (<tt>index < 0 || index > size()</tt>). |
340 |
> |
* @param index index of the element to replace |
341 |
> |
* @param element element to be stored at the specified position |
342 |
> |
* @return the element previously at the specified position |
343 |
> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
344 |
|
*/ |
345 |
|
public E set(int index, E element) { |
346 |
|
Entry<E> e = entry(index); |
354 |
|
* Shifts the element currently at that position (if any) and any |
355 |
|
* subsequent elements to the right (adds one to their indices). |
356 |
|
* |
357 |
< |
* @param index index at which the specified element is to be inserted. |
358 |
< |
* @param element element to be inserted. |
359 |
< |
* |
340 |
< |
* @throws IndexOutOfBoundsException if the index is out of range |
341 |
< |
* (<tt>index < 0 || index > size()</tt>). |
357 |
> |
* @param index index at which the specified element is to be inserted |
358 |
> |
* @param element element to be inserted |
359 |
> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
360 |
|
*/ |
361 |
|
public void add(int index, E element) { |
362 |
|
addBefore(element, (index==size ? header : entry(index))); |
367 |
|
* subsequent elements to the left (subtracts one from their indices). |
368 |
|
* Returns the element that was removed from the list. |
369 |
|
* |
370 |
< |
* @param index the index of the element to removed. |
371 |
< |
* @return the element previously at the specified position. |
372 |
< |
* |
355 |
< |
* @throws IndexOutOfBoundsException if the index is out of range |
356 |
< |
* (<tt>index < 0 || index > size()</tt>). |
370 |
> |
* @param index the index of the element to be removed |
371 |
> |
* @return the element previously at the specified position |
372 |
> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
373 |
|
*/ |
374 |
|
public E remove(int index) { |
375 |
|
return remove(entry(index)); |
397 |
|
// Search Operations |
398 |
|
|
399 |
|
/** |
400 |
< |
* Returns the index in this list of the first occurrence of the |
401 |
< |
* specified element, or -1 if the List does not contain this |
402 |
< |
* element. More formally, returns the lowest index i such that |
403 |
< |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, or -1 if |
404 |
< |
* there is no such index. |
405 |
< |
* |
406 |
< |
* @param o element to search for. |
407 |
< |
* @return the index in this list of the first occurrence of the |
408 |
< |
* specified element, or -1 if the list does not contain this |
393 |
< |
* element. |
400 |
> |
* Returns the index of the first occurrence of the specified element |
401 |
> |
* in this list, or -1 if this list does not contain the element. |
402 |
> |
* More formally, returns the lowest index <tt>i</tt> such that |
403 |
> |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, |
404 |
> |
* or -1 if there is no such index. |
405 |
> |
* |
406 |
> |
* @param o element to search for |
407 |
> |
* @return the index of the first occurrence of the specified element in |
408 |
> |
* this list, or -1 if this list does not contain the element |
409 |
|
*/ |
410 |
|
public int indexOf(Object o) { |
411 |
|
int index = 0; |
426 |
|
} |
427 |
|
|
428 |
|
/** |
429 |
< |
* Returns the index in this list of the last occurrence of the |
430 |
< |
* specified element, or -1 if the list does not contain this |
431 |
< |
* element. More formally, returns the highest index i such that |
432 |
< |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, or -1 if |
433 |
< |
* there is no such index. |
434 |
< |
* |
435 |
< |
* @param o element to search for. |
436 |
< |
* @return the index in this list of the last occurrence of the |
437 |
< |
* specified element, or -1 if the list does not contain this |
423 |
< |
* element. |
429 |
> |
* Returns the index of the last occurrence of the specified element |
430 |
> |
* in this list, or -1 if this list does not contain the element. |
431 |
> |
* More formally, returns the highest index <tt>i</tt> such that |
432 |
> |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, |
433 |
> |
* or -1 if there is no such index. |
434 |
> |
* |
435 |
> |
* @param o element to search for |
436 |
> |
* @return the index of the last occurrence of the specified element in |
437 |
> |
* this list, or -1 if this list does not contain the element |
438 |
|
*/ |
439 |
|
public int lastIndexOf(Object o) { |
440 |
|
int index = size; |
458 |
|
|
459 |
|
/** |
460 |
|
* Retrieves, but does not remove, the head (first element) of this list. |
461 |
< |
* @return the head of this list, or <tt>null</tt> if this list is empty. |
461 |
> |
* @return the head of this list, or <tt>null</tt> if this list is empty |
462 |
|
* @since 1.5 |
463 |
|
*/ |
464 |
|
public E peek() { |
469 |
|
|
470 |
|
/** |
471 |
|
* Retrieves, but does not remove, the head (first element) of this list. |
472 |
< |
* @return the head of this list. |
473 |
< |
* @throws NoSuchElementException if this list is empty. |
472 |
> |
* @return the head of this list |
473 |
> |
* @throws NoSuchElementException if this list is empty |
474 |
|
* @since 1.5 |
475 |
|
*/ |
476 |
|
public E element() { |
478 |
|
} |
479 |
|
|
480 |
|
/** |
481 |
< |
* Retrieves and removes the head (first element) of this list. |
482 |
< |
* @return the head of this list, or <tt>null</tt> if this list is empty. |
481 |
> |
* Retrieves and removes the head (first element) of this list |
482 |
> |
* @return the head of this list, or <tt>null</tt> if this list is empty |
483 |
|
* @since 1.5 |
484 |
|
*/ |
485 |
|
public E poll() { |
490 |
|
|
491 |
|
/** |
492 |
|
* Retrieves and removes the head (first element) of this list. |
493 |
< |
* @return the head of this list. |
494 |
< |
* @throws NoSuchElementException if this list is empty. |
493 |
> |
* |
494 |
> |
* @return the head of this list |
495 |
> |
* @throws NoSuchElementException if this list is empty |
496 |
|
* @since 1.5 |
497 |
|
*/ |
498 |
|
public E remove() { |
502 |
|
/** |
503 |
|
* Adds the specified element as the tail (last element) of this list. |
504 |
|
* |
505 |
< |
* @param e the element to add. |
506 |
< |
* @return <tt>true</tt> (as per the general contract of |
492 |
< |
* <tt>Queue.offer</tt>) |
505 |
> |
* @param e the element to add |
506 |
> |
* @return <tt>true</tt> (as specified by {@link Queue#offer}) |
507 |
|
* @since 1.5 |
508 |
|
*/ |
509 |
|
public boolean offer(E e) { |
515 |
|
* Inserts the specified element at the front of this list. |
516 |
|
* |
517 |
|
* @param e the element to insert |
518 |
< |
* @return <tt>true</tt> (as per the spec for {@link Deque#offerFirst}) |
518 |
> |
* @return <tt>true</tt> (as specified by {@link Deque#offerFirst}) |
519 |
|
* @since 1.6 |
520 |
|
*/ |
521 |
|
public boolean offerFirst(E e) { |
527 |
|
* Inserts the specified element at the end of this list. |
528 |
|
* |
529 |
|
* @param e the element to insert |
530 |
< |
* @return <tt>true</tt> (as per the spec for {@link Deque#offerLast}) |
530 |
> |
* @return <tt>true</tt> (as specified by {@link Deque#offerLast}) |
531 |
|
* @since 1.6 |
532 |
|
*/ |
533 |
|
public boolean offerLast(E e) { |
537 |
|
|
538 |
|
/** |
539 |
|
* Retrieves, but does not remove, the first element of this list, |
540 |
< |
* returning <tt>null</tt> if this list is empty. |
540 |
> |
* or returns <tt>null</tt> if this list is empty. |
541 |
|
* |
542 |
< |
* @return the first element of this list, or <tt>null</tt> if |
543 |
< |
* this list is empty |
542 |
> |
* @return the first element of this list, or <tt>null</tt> |
543 |
> |
* if this list is empty |
544 |
|
* @since 1.6 |
545 |
|
*/ |
546 |
|
public E peekFirst() { |
551 |
|
|
552 |
|
/** |
553 |
|
* Retrieves, but does not remove, the last element of this list, |
554 |
< |
* returning <tt>null</tt> if this list is empty. |
554 |
> |
* or returns <tt>null</tt> if this list is empty. |
555 |
|
* |
556 |
< |
* @return the last element of this list, or <tt>null</tt> if this list |
557 |
< |
* is empty |
556 |
> |
* @return the last element of this list, or <tt>null</tt> |
557 |
> |
* if this list is empty |
558 |
|
* @since 1.6 |
559 |
|
*/ |
560 |
|
public E peekLast() { |
564 |
|
} |
565 |
|
|
566 |
|
/** |
567 |
< |
* Retrieves and removes the first element of this list, or |
568 |
< |
* <tt>null</tt> if this list is empty. |
567 |
> |
* Retrieves and removes the first element of this list, |
568 |
> |
* or returns <tt>null</tt> if this list is empty. |
569 |
|
* |
570 |
|
* @return the first element of this list, or <tt>null</tt> if |
571 |
|
* this list is empty |
578 |
|
} |
579 |
|
|
580 |
|
/** |
581 |
< |
* Retrieves and removes the last element of this list, or |
582 |
< |
* <tt>null</tt> if this list is empty. |
581 |
> |
* Retrieves and removes the last element of this list, |
582 |
> |
* or returns <tt>null</tt> if this list is empty. |
583 |
|
* |
584 |
|
* @return the last element of this list, or <tt>null</tt> if |
585 |
|
* this list is empty |
611 |
|
* <p>This method is equivalent to {@link #removeFirst()}. |
612 |
|
* |
613 |
|
* @return the element at the front of this list (which is the top |
614 |
< |
* of the stack represented by this list) |
615 |
< |
* @throws NoSuchElementException if this list is empty. |
614 |
> |
* of the stack represented by this list) |
615 |
> |
* @throws NoSuchElementException if this list is empty |
616 |
|
* @since 1.6 |
617 |
|
*/ |
618 |
|
public E pop() { |
643 |
|
*/ |
644 |
|
public boolean removeLastOccurrence(Object o) { |
645 |
|
if (o==null) { |
646 |
< |
for (Entry e = header.previous; e != header; e = e.previous) { |
646 |
> |
for (Entry<E> e = header.previous; e != header; e = e.previous) { |
647 |
|
if (e.element==null) { |
648 |
|
remove(e); |
649 |
|
return true; |
650 |
|
} |
651 |
|
} |
652 |
|
} else { |
653 |
< |
for (Entry e = header.previous; e != header; e = e.previous) { |
653 |
> |
for (Entry<E> e = header.previous; e != header; e = e.previous) { |
654 |
|
if (o.equals(e.element)) { |
655 |
|
remove(e); |
656 |
|
return true; |
674 |
|
* than risking arbitrary, non-deterministic behavior at an undetermined |
675 |
|
* time in the future. |
676 |
|
* |
677 |
< |
* @param index index of first element to be returned from the |
678 |
< |
* list-iterator (by a call to <tt>next</tt>). |
677 |
> |
* @param index index of the first element to be returned from the |
678 |
> |
* list-iterator (by a call to <tt>next</tt>) |
679 |
|
* @return a ListIterator of the elements in this list (in proper |
680 |
< |
* sequence), starting at the specified position in the list. |
681 |
< |
* @throws IndexOutOfBoundsException if the index is out of range |
668 |
< |
* (<tt>index < 0 || index > size()</tt>). |
680 |
> |
* sequence), starting at the specified position in the list |
681 |
> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
682 |
|
* @see List#listIterator(int) |
683 |
|
*/ |
684 |
|
public ListIterator<E> listIterator(int index) { |
685 |
< |
return new ListItr(index); |
685 |
> |
return new ListItr(index); |
686 |
|
} |
687 |
|
|
688 |
|
private class ListItr implements ListIterator<E> { |
689 |
< |
private Entry<E> lastReturned = header; |
690 |
< |
private Entry<E> next; |
691 |
< |
private int nextIndex; |
692 |
< |
private int expectedModCount = modCount; |
693 |
< |
|
694 |
< |
ListItr(int index) { |
695 |
< |
if (index < 0 || index > size) |
696 |
< |
throw new IndexOutOfBoundsException("Index: "+index+ |
697 |
< |
", Size: "+size); |
698 |
< |
if (index < (size >> 1)) { |
699 |
< |
next = header.next; |
700 |
< |
for (nextIndex=0; nextIndex<index; nextIndex++) |
701 |
< |
next = next.next; |
702 |
< |
} else { |
703 |
< |
next = header; |
704 |
< |
for (nextIndex=size; nextIndex>index; nextIndex--) |
705 |
< |
next = next.previous; |
706 |
< |
} |
707 |
< |
} |
708 |
< |
|
709 |
< |
public boolean hasNext() { |
710 |
< |
return nextIndex != size; |
711 |
< |
} |
712 |
< |
|
713 |
< |
public E next() { |
714 |
< |
checkForComodification(); |
715 |
< |
if (nextIndex == size) |
716 |
< |
throw new NoSuchElementException(); |
717 |
< |
|
718 |
< |
lastReturned = next; |
719 |
< |
next = next.next; |
720 |
< |
nextIndex++; |
721 |
< |
return lastReturned.element; |
722 |
< |
} |
723 |
< |
|
724 |
< |
public boolean hasPrevious() { |
725 |
< |
return nextIndex != 0; |
726 |
< |
} |
727 |
< |
|
728 |
< |
public E previous() { |
729 |
< |
if (nextIndex == 0) |
730 |
< |
throw new NoSuchElementException(); |
718 |
< |
|
719 |
< |
lastReturned = next = next.previous; |
720 |
< |
nextIndex--; |
721 |
< |
checkForComodification(); |
722 |
< |
return lastReturned.element; |
723 |
< |
} |
724 |
< |
|
725 |
< |
public int nextIndex() { |
726 |
< |
return nextIndex; |
727 |
< |
} |
728 |
< |
|
729 |
< |
public int previousIndex() { |
730 |
< |
return nextIndex-1; |
731 |
< |
} |
689 |
> |
private Entry<E> lastReturned = header; |
690 |
> |
private Entry<E> next; |
691 |
> |
private int nextIndex; |
692 |
> |
private int expectedModCount = modCount; |
693 |
> |
|
694 |
> |
ListItr(int index) { |
695 |
> |
if (index < 0 || index > size) |
696 |
> |
throw new IndexOutOfBoundsException("Index: "+index+ |
697 |
> |
", Size: "+size); |
698 |
> |
if (index < (size >> 1)) { |
699 |
> |
next = header.next; |
700 |
> |
for (nextIndex=0; nextIndex<index; nextIndex++) |
701 |
> |
next = next.next; |
702 |
> |
} else { |
703 |
> |
next = header; |
704 |
> |
for (nextIndex=size; nextIndex>index; nextIndex--) |
705 |
> |
next = next.previous; |
706 |
> |
} |
707 |
> |
} |
708 |
> |
|
709 |
> |
public boolean hasNext() { |
710 |
> |
return nextIndex != size; |
711 |
> |
} |
712 |
> |
|
713 |
> |
public E next() { |
714 |
> |
checkForComodification(); |
715 |
> |
if (nextIndex == size) |
716 |
> |
throw new NoSuchElementException(); |
717 |
> |
|
718 |
> |
lastReturned = next; |
719 |
> |
next = next.next; |
720 |
> |
nextIndex++; |
721 |
> |
return lastReturned.element; |
722 |
> |
} |
723 |
> |
|
724 |
> |
public boolean hasPrevious() { |
725 |
> |
return nextIndex != 0; |
726 |
> |
} |
727 |
> |
|
728 |
> |
public E previous() { |
729 |
> |
if (nextIndex == 0) |
730 |
> |
throw new NoSuchElementException(); |
731 |
|
|
732 |
< |
public void remove() { |
732 |
> |
lastReturned = next = next.previous; |
733 |
> |
nextIndex--; |
734 |
> |
checkForComodification(); |
735 |
> |
return lastReturned.element; |
736 |
> |
} |
737 |
> |
|
738 |
> |
public int nextIndex() { |
739 |
> |
return nextIndex; |
740 |
> |
} |
741 |
> |
|
742 |
> |
public int previousIndex() { |
743 |
> |
return nextIndex-1; |
744 |
> |
} |
745 |
> |
|
746 |
> |
public void remove() { |
747 |
|
checkForComodification(); |
748 |
|
Entry<E> lastNext = lastReturned.next; |
749 |
|
try { |
751 |
|
} catch (NoSuchElementException e) { |
752 |
|
throw new IllegalStateException(); |
753 |
|
} |
754 |
< |
if (next==lastReturned) |
754 |
> |
if (next==lastReturned) |
755 |
|
next = lastNext; |
756 |
|
else |
757 |
< |
nextIndex--; |
758 |
< |
lastReturned = header; |
759 |
< |
expectedModCount++; |
760 |
< |
} |
761 |
< |
|
762 |
< |
public void set(E e) { |
763 |
< |
if (lastReturned == header) |
764 |
< |
throw new IllegalStateException(); |
765 |
< |
checkForComodification(); |
766 |
< |
lastReturned.element = e; |
767 |
< |
} |
768 |
< |
|
769 |
< |
public void add(E e) { |
770 |
< |
checkForComodification(); |
771 |
< |
lastReturned = header; |
772 |
< |
addBefore(e, next); |
773 |
< |
nextIndex++; |
774 |
< |
expectedModCount++; |
775 |
< |
} |
776 |
< |
|
777 |
< |
final void checkForComodification() { |
778 |
< |
if (modCount != expectedModCount) |
779 |
< |
throw new ConcurrentModificationException(); |
780 |
< |
} |
757 |
> |
nextIndex--; |
758 |
> |
lastReturned = header; |
759 |
> |
expectedModCount++; |
760 |
> |
} |
761 |
> |
|
762 |
> |
public void set(E e) { |
763 |
> |
if (lastReturned == header) |
764 |
> |
throw new IllegalStateException(); |
765 |
> |
checkForComodification(); |
766 |
> |
lastReturned.element = e; |
767 |
> |
} |
768 |
> |
|
769 |
> |
public void add(E e) { |
770 |
> |
checkForComodification(); |
771 |
> |
lastReturned = header; |
772 |
> |
addBefore(e, next); |
773 |
> |
nextIndex++; |
774 |
> |
expectedModCount++; |
775 |
> |
} |
776 |
> |
|
777 |
> |
final void checkForComodification() { |
778 |
> |
if (modCount != expectedModCount) |
779 |
> |
throw new ConcurrentModificationException(); |
780 |
> |
} |
781 |
|
} |
782 |
|
|
783 |
|
private static class Entry<E> { |
784 |
< |
E element; |
785 |
< |
Entry<E> next; |
786 |
< |
Entry<E> previous; |
787 |
< |
|
788 |
< |
Entry(E element, Entry<E> next, Entry<E> previous) { |
789 |
< |
this.element = element; |
790 |
< |
this.next = next; |
791 |
< |
this.previous = previous; |
792 |
< |
} |
784 |
> |
E element; |
785 |
> |
Entry<E> next; |
786 |
> |
Entry<E> previous; |
787 |
> |
|
788 |
> |
Entry(E element, Entry<E> next, Entry<E> previous) { |
789 |
> |
this.element = element; |
790 |
> |
this.next = next; |
791 |
> |
this.previous = previous; |
792 |
> |
} |
793 |
|
} |
794 |
|
|
795 |
|
private Entry<E> addBefore(E e, Entry<E> entry) { |
796 |
< |
Entry<E> newEntry = new Entry<E>(e, entry, entry.previous); |
797 |
< |
newEntry.previous.next = newEntry; |
798 |
< |
newEntry.next.previous = newEntry; |
799 |
< |
size++; |
800 |
< |
modCount++; |
801 |
< |
return newEntry; |
796 |
> |
Entry<E> newEntry = new Entry<E>(e, entry, entry.previous); |
797 |
> |
newEntry.previous.next = newEntry; |
798 |
> |
newEntry.next.previous = newEntry; |
799 |
> |
size++; |
800 |
> |
modCount++; |
801 |
> |
return newEntry; |
802 |
|
} |
803 |
|
|
804 |
|
private E remove(Entry<E> e) { |
805 |
< |
if (e == header) |
806 |
< |
throw new NoSuchElementException(); |
805 |
> |
if (e == header) |
806 |
> |
throw new NoSuchElementException(); |
807 |
|
|
808 |
|
E result = e.element; |
809 |
< |
e.previous.next = e.next; |
810 |
< |
e.next.previous = e.previous; |
809 |
> |
e.previous.next = e.next; |
810 |
> |
e.next.previous = e.previous; |
811 |
|
e.next = e.previous = null; |
812 |
|
e.element = null; |
813 |
< |
size--; |
814 |
< |
modCount++; |
813 |
> |
size--; |
814 |
> |
modCount++; |
815 |
|
return result; |
816 |
|
} |
817 |
|
|
818 |
|
/** |
819 |
+ |
* @since 1.6 |
820 |
+ |
*/ |
821 |
+ |
public Iterator<E> descendingIterator() { |
822 |
+ |
return new DescendingIterator(); |
823 |
+ |
} |
824 |
+ |
|
825 |
+ |
/** Adapter to provide descending iterators via ListItr.previous */ |
826 |
+ |
private class DescendingIterator implements Iterator { |
827 |
+ |
final ListItr itr = new ListItr(size()); |
828 |
+ |
public boolean hasNext() { |
829 |
+ |
return itr.hasPrevious(); |
830 |
+ |
} |
831 |
+ |
public E next() { |
832 |
+ |
return itr.previous(); |
833 |
+ |
} |
834 |
+ |
public void remove() { |
835 |
+ |
itr.remove(); |
836 |
+ |
} |
837 |
+ |
} |
838 |
+ |
|
839 |
+ |
/** |
840 |
|
* Returns a shallow copy of this <tt>LinkedList</tt>. (The elements |
841 |
|
* themselves are not cloned.) |
842 |
|
* |
843 |
< |
* @return a shallow copy of this <tt>LinkedList</tt> instance. |
843 |
> |
* @return a shallow copy of this <tt>LinkedList</tt> instance |
844 |
|
*/ |
845 |
|
public Object clone() { |
846 |
|
LinkedList<E> clone = null; |
847 |
< |
try { |
848 |
< |
clone = (LinkedList<E>) super.clone(); |
849 |
< |
} catch (CloneNotSupportedException e) { |
850 |
< |
throw new InternalError(); |
851 |
< |
} |
847 |
> |
try { |
848 |
> |
clone = (LinkedList<E>) super.clone(); |
849 |
> |
} catch (CloneNotSupportedException e) { |
850 |
> |
throw new InternalError(); |
851 |
> |
} |
852 |
|
|
853 |
|
// Put clone into "virgin" state |
854 |
|
clone.header = new Entry<E>(null, null, null); |
865 |
|
|
866 |
|
/** |
867 |
|
* Returns an array containing all of the elements in this list |
868 |
< |
* in the correct order. |
868 |
> |
* in proper sequence (from first to last element). |
869 |
> |
* |
870 |
> |
* <p>The returned array will be "safe" in that no references to it are |
871 |
> |
* maintained by this list. (In other words, this method must allocate |
872 |
> |
* a new array). The caller is thus free to modify the returned array. |
873 |
> |
* |
874 |
> |
* <p>This method acts as bridge between array-based and collection-based |
875 |
> |
* APIs. |
876 |
|
* |
877 |
|
* @return an array containing all of the elements in this list |
878 |
< |
* in the correct order. |
878 |
> |
* in proper sequence |
879 |
|
*/ |
880 |
|
public Object[] toArray() { |
881 |
< |
Object[] result = new Object[size]; |
881 |
> |
Object[] result = new Object[size]; |
882 |
|
int i = 0; |
883 |
|
for (Entry<E> e = header.next; e != header; e = e.next) |
884 |
|
result[i++] = e.element; |
885 |
< |
return result; |
885 |
> |
return result; |
886 |
|
} |
887 |
|
|
888 |
|
/** |
889 |
|
* Returns an array containing all of the elements in this list in |
890 |
< |
* the correct order; the runtime type of the returned array is that of |
891 |
< |
* the specified array. If the list fits in the specified array, it |
892 |
< |
* is returned therein. Otherwise, a new array is allocated with the |
893 |
< |
* runtime type of the specified array and the size of this list.<p> |
894 |
< |
* |
895 |
< |
* If the list fits in the specified array with room to spare |
896 |
< |
* (i.e., the array has more elements than the list), |
897 |
< |
* the element in the array immediately following the end of the |
898 |
< |
* collection is set to null. This is useful in determining the length |
899 |
< |
* of the list <i>only</i> if the caller knows that the list |
900 |
< |
* does not contain any null elements. |
890 |
> |
* proper sequence (from first to last element); the runtime type of |
891 |
> |
* the returned array is that of the specified array. If the list fits |
892 |
> |
* in the specified array, it is returned therein. Otherwise, a new |
893 |
> |
* array is allocated with the runtime type of the specified array and |
894 |
> |
* the size of this list. |
895 |
> |
* |
896 |
> |
* <p>If the list fits in the specified array with room to spare (i.e., |
897 |
> |
* the array has more elements than the list), the element in the array |
898 |
> |
* immediately following the end of the list is set to <tt>null</tt>. |
899 |
> |
* (This is useful in determining the length of the list <i>only</i> if |
900 |
> |
* the caller knows that the list does not contain any null elements.) |
901 |
> |
* |
902 |
> |
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
903 |
> |
* array-based and collection-based APIs. Further, this method allows |
904 |
> |
* precise control over the runtime type of the output array, and may, |
905 |
> |
* under certain circumstances, be used to save allocation costs. |
906 |
> |
* |
907 |
> |
* <p>Suppose <tt>x</tt> is a list known to contain only strings. |
908 |
> |
* The following code can be used to dump the list into a newly |
909 |
> |
* allocated array of <tt>String</tt>: |
910 |
> |
* |
911 |
> |
* <pre> |
912 |
> |
* String[] y = x.toArray(new String[0]);</pre> |
913 |
> |
* |
914 |
> |
* Note that <tt>toArray(new Object[0])</tt> is identical in function to |
915 |
> |
* <tt>toArray()</tt>. |
916 |
|
* |
917 |
|
* @param a the array into which the elements of the list are to |
918 |
< |
* be stored, if it is big enough; otherwise, a new array of the |
919 |
< |
* same runtime type is allocated for this purpose. |
920 |
< |
* @return an array containing the elements of the list. |
921 |
< |
* @throws ArrayStoreException if the runtime type of a is not a |
922 |
< |
* supertype of the runtime type of every element in this list. |
923 |
< |
* @throws NullPointerException if the specified array is null. |
918 |
> |
* be stored, if it is big enough; otherwise, a new array of the |
919 |
> |
* same runtime type is allocated for this purpose. |
920 |
> |
* @return an array containing the elements of the list |
921 |
> |
* @throws ArrayStoreException if the runtime type of the specified array |
922 |
> |
* is not a supertype of the runtime type of every element in |
923 |
> |
* this list |
924 |
> |
* @throws NullPointerException if the specified array is null |
925 |
|
*/ |
926 |
|
public <T> T[] toArray(T[] a) { |
927 |
|
if (a.length < size) |
928 |
|
a = (T[])java.lang.reflect.Array.newInstance( |
929 |
|
a.getClass().getComponentType(), size); |
930 |
|
int i = 0; |
931 |
< |
Object[] result = a; |
931 |
> |
Object[] result = a; |
932 |
|
for (Entry<E> e = header.next; e != header; e = e.next) |
933 |
|
result[i++] = e.element; |
934 |
|
|
945 |
|
* is, serialize it). |
946 |
|
* |
947 |
|
* @serialData The size of the list (the number of elements it |
948 |
< |
* contains) is emitted (int), followed by all of its |
949 |
< |
* elements (each an Object) in the proper order. |
948 |
> |
* contains) is emitted (int), followed by all of its |
949 |
> |
* elements (each an Object) in the proper order. |
950 |
|
*/ |
951 |
|
private void writeObject(java.io.ObjectOutputStream s) |
952 |
|
throws java.io.IOException { |
953 |
< |
// Write out any hidden serialization magic |
954 |
< |
s.defaultWriteObject(); |
953 |
> |
// Write out any hidden serialization magic |
954 |
> |
s.defaultWriteObject(); |
955 |
|
|
956 |
|
// Write out size |
957 |
|
s.writeInt(size); |
958 |
|
|
959 |
< |
// Write out all elements in the proper order. |
959 |
> |
// Write out all elements in the proper order. |
960 |
|
for (Entry e = header.next; e != header; e = e.next) |
961 |
|
s.writeObject(e.element); |
962 |
|
} |
967 |
|
*/ |
968 |
|
private void readObject(java.io.ObjectInputStream s) |
969 |
|
throws java.io.IOException, ClassNotFoundException { |
970 |
< |
// Read in any hidden serialization magic |
971 |
< |
s.defaultReadObject(); |
970 |
> |
// Read in any hidden serialization magic |
971 |
> |
s.defaultReadObject(); |
972 |
|
|
973 |
|
// Read in size |
974 |
|
int size = s.readInt(); |
977 |
|
header = new Entry<E>(null, null, null); |
978 |
|
header.next = header.previous = header; |
979 |
|
|
980 |
< |
// Read in all elements in the proper order. |
981 |
< |
for (int i=0; i<size; i++) |
980 |
> |
// Read in all elements in the proper order. |
981 |
> |
for (int i=0; i<size; i++) |
982 |
|
addBefore((E)s.readObject(), header); |
983 |
|
} |
984 |
|
} |