8 |
|
package java.util; |
9 |
|
|
10 |
|
/** |
11 |
< |
* This class provides a skeletal implementation of the <tt>List</tt> |
11 |
> |
* This class provides a skeletal implementation of the {@link List} |
12 |
|
* interface to minimize the effort required to implement this interface |
13 |
|
* backed by a "random access" data store (such as an array). For sequential |
14 |
< |
* access data (such as a linked list), <tt>AbstractSequentialList</tt> should |
15 |
< |
* be used in preference to this class.<p> |
14 |
> |
* access data (such as a linked list), {@link AbstractSequentialList} should |
15 |
> |
* be used in preference to this class. |
16 |
|
* |
17 |
< |
* To implement an unmodifiable list, the programmer needs only to extend this |
18 |
< |
* class and provide implementations for the <tt>get(int index)</tt> and |
19 |
< |
* <tt>size()</tt> methods.<p> |
17 |
> |
* <p>To implement an unmodifiable list, the programmer needs only to extend |
18 |
> |
* this class and provide implementations for the {@link #get(int)} and |
19 |
> |
* {@link List#size() size()} methods. |
20 |
|
* |
21 |
< |
* 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> |
21 |
> |
* <p>To implement a modifiable list, the programmer must additionally |
22 |
> |
* override the {@link #set(int, Object) set(int, E)} method (which otherwise |
23 |
> |
* throws an {@code UnsupportedOperationException}). If the list is |
24 |
> |
* variable-size the programmer must additionally override the |
25 |
> |
* {@link #add(int, Object) add(int, E)} and {@link #remove(int)} methods. |
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> |
27 |
> |
* <p>The programmer should generally provide a void (no argument) and collection |
28 |
> |
* constructor, as per the recommendation in the {@link Collection} interface |
29 |
> |
* specification. |
30 |
|
* |
31 |
< |
* Unlike the other abstract collection implementations, the programmer does |
31 |
> |
* <p>Unlike the other abstract collection implementations, the programmer does |
32 |
|
* <i>not</i> have to provide an iterator implementation; the iterator and |
33 |
|
* list iterator are implemented by this class, on top of the "random access" |
34 |
< |
* methods: <tt>get(int index)</tt>, <tt>set(int index, E element)</tt>, |
35 |
< |
* <tt>add(int index, E element)</tt> and <tt>remove(int index)</tt>.<p> |
34 |
> |
* methods: |
35 |
> |
* {@link #get(int)}, |
36 |
> |
* {@link #set(int, Object) set(int, E)}, |
37 |
> |
* {@link #add(int, Object) add(int, E)} and |
38 |
> |
* {@link #remove(int)}. |
39 |
|
* |
40 |
< |
* The documentation for each non-abstract methods in this class describes its |
40 |
> |
* <p>The documentation for each non-abstract method in this class describes its |
41 |
|
* implementation in detail. Each of these methods may be overridden if the |
42 |
< |
* collection being implemented admits a more efficient implementation.<p> |
42 |
> |
* collection being implemented admits a more efficient implementation. |
43 |
|
* |
44 |
< |
* This class is a member of the |
45 |
< |
* <a href="{@docRoot}/../guide/collections/index.html"> |
44 |
> |
* <p>This class is a member of the |
45 |
> |
* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
46 |
|
* Java Collections Framework</a>. |
47 |
|
* |
48 |
|
* @author Josh Bloch |
49 |
|
* @author Neal Gafter |
50 |
< |
* @version 1.37, 01/18/03 |
48 |
< |
* @see Collection |
49 |
< |
* @see List |
50 |
< |
* @see AbstractSequentialList |
51 |
< |
* @see AbstractCollection |
50 |
> |
* @version %I%, %G% |
51 |
|
* @since 1.2 |
52 |
|
*/ |
53 |
|
|
70 |
|
* classes should clearly specify in their documentation any restrictions |
71 |
|
* on what elements may be added. |
72 |
|
* |
73 |
< |
* <p>This implementation calls <tt>add(size(), e)</tt>. |
73 |
> |
* <p>This implementation calls {@code add(size(), e)}. |
74 |
|
* |
75 |
|
* <p>Note that this implementation throws an |
76 |
< |
* <tt>UnsupportedOperationException</tt> unless <tt>add(int, Object)</tt> |
77 |
< |
* is overridden. |
76 |
> |
* {@code UnsupportedOperationException} unless |
77 |
> |
* {@link #add(int, Object) add(int, E)} is overridden. |
78 |
|
* |
79 |
|
* @param e element to be appended to this list |
80 |
< |
* @return <tt>true</tt> (as specified by {@link Collection#add}) |
81 |
< |
* @throws UnsupportedOperationException if the <tt>add</tt> operation |
80 |
> |
* @return {@code true} (as specified by {@link Collection#add}) |
81 |
> |
* @throws UnsupportedOperationException if the {@code add} operation |
82 |
|
* is not supported by this list |
83 |
|
* @throws ClassCastException if the class of the specified element |
84 |
|
* prevents it from being added to this list |
103 |
|
* {@inheritDoc} |
104 |
|
* |
105 |
|
* <p>This implementation always throws an |
106 |
< |
* <tt>UnsupportedOperationException</tt>. |
106 |
> |
* {@code UnsupportedOperationException}. |
107 |
|
* |
108 |
|
* @throws UnsupportedOperationException {@inheritDoc} |
109 |
|
* @throws ClassCastException {@inheritDoc} |
119 |
|
* {@inheritDoc} |
120 |
|
* |
121 |
|
* <p>This implementation always throws an |
122 |
< |
* <tt>UnsupportedOperationException</tt>. |
122 |
> |
* {@code UnsupportedOperationException}. |
123 |
|
* |
124 |
|
* @throws UnsupportedOperationException {@inheritDoc} |
125 |
|
* @throws ClassCastException {@inheritDoc} |
135 |
|
* {@inheritDoc} |
136 |
|
* |
137 |
|
* <p>This implementation always throws an |
138 |
< |
* <tt>UnsupportedOperationException</tt>. |
138 |
> |
* {@code UnsupportedOperationException}. |
139 |
|
* |
140 |
|
* @throws UnsupportedOperationException {@inheritDoc} |
141 |
|
* @throws IndexOutOfBoundsException {@inheritDoc} |
151 |
|
* {@inheritDoc} |
152 |
|
* |
153 |
|
* <p>This implementation first gets a list iterator (with |
154 |
< |
* <tt>listIterator()</tt>). Then, it iterates over the list until the |
154 |
> |
* {@code listIterator()}). Then, it iterates over the list until the |
155 |
|
* specified element is found or the end of the list is reached. |
156 |
|
* |
157 |
|
* @throws ClassCastException {@inheritDoc} |
175 |
|
* {@inheritDoc} |
176 |
|
* |
177 |
|
* <p>This implementation first gets a list iterator that points to the end |
178 |
< |
* of the list (with <tt>listIterator(size())</tt>). Then, it iterates |
178 |
> |
* of the list (with {@code listIterator(size())}). Then, it iterates |
179 |
|
* backwards over the list until the specified element is found, or the |
180 |
|
* beginning of the list is reached. |
181 |
|
* |
203 |
|
* Removes all of the elements from this list (optional operation). |
204 |
|
* The list will be empty after this call returns. |
205 |
|
* |
206 |
< |
* <p>This implementation calls <tt>removeRange(0, size())</tt>. |
206 |
> |
* <p>This implementation calls {@code removeRange(0, size())}. |
207 |
|
* |
208 |
|
* <p>Note that this implementation throws an |
209 |
< |
* <tt>UnsupportedOperationException</tt> unless <tt>remove(int |
210 |
< |
* index)</tt> or <tt>removeRange(int fromIndex, int toIndex)</tt> is |
209 |
> |
* {@code UnsupportedOperationException} unless {@code remove(int |
210 |
> |
* index)} or {@code removeRange(int fromIndex, int toIndex)} is |
211 |
|
* overridden. |
212 |
|
* |
213 |
< |
* @throws UnsupportedOperationException if the <tt>clear</tt> operation |
213 |
> |
* @throws UnsupportedOperationException if the {@code clear} operation |
214 |
|
* is not supported by this list |
215 |
|
*/ |
216 |
|
public void clear() { |
220 |
|
/** |
221 |
|
* {@inheritDoc} |
222 |
|
* |
223 |
< |
* <p>This implementation gets an iterator over the specified collection and |
224 |
< |
* iterates over it, inserting the elements obtained from the iterator |
225 |
< |
* into this list at the appropriate position, one at a time, using |
226 |
< |
* <tt>add(int, Object)</tt>. Many implementations will override this |
227 |
< |
* method for efficiency. |
223 |
> |
* <p>This implementation gets an iterator over the specified collection |
224 |
> |
* and iterates over it, inserting the elements obtained from the |
225 |
> |
* iterator into this list at the appropriate position, one at a time, |
226 |
> |
* using {@code add(int, E)}. |
227 |
> |
* Many implementations will override this method for efficiency. |
228 |
|
* |
229 |
|
* <p>Note that this implementation throws an |
230 |
< |
* <tt>UnsupportedOperationException</tt> unless <tt>add(int, Object)</tt> |
231 |
< |
* is overridden. |
230 |
> |
* {@code UnsupportedOperationException} unless |
231 |
> |
* {@link #add(int, Object) add(int, E)} is overridden. |
232 |
|
* |
233 |
|
* @throws UnsupportedOperationException {@inheritDoc} |
234 |
|
* @throws ClassCastException {@inheritDoc} |
250 |
|
// Iterators |
251 |
|
|
252 |
|
/** |
253 |
< |
* Returns an iterator over the elements in this list in proper |
255 |
< |
* sequence. <p> |
253 |
> |
* Returns an iterator over the elements in this list in proper sequence. |
254 |
|
* |
255 |
< |
* This implementation returns a straightforward implementation of the |
256 |
< |
* iterator interface, relying on the backing list's <tt>size()</tt>, |
257 |
< |
* <tt>get(int)</tt>, and <tt>remove(int)</tt> methods.<p> |
258 |
< |
* |
259 |
< |
* Note that the iterator returned by this method will throw an |
260 |
< |
* <tt>UnsupportedOperationException</tt> in response to its |
261 |
< |
* <tt>remove</tt> method unless the list's <tt>remove(int)</tt> method is |
262 |
< |
* overridden.<p> |
263 |
< |
* |
264 |
< |
* This implementation can be made to throw runtime exceptions in the face |
265 |
< |
* of concurrent modification, as described in the specification for the |
266 |
< |
* (protected) <tt>modCount</tt> field. |
255 |
> |
* <p>This implementation returns a straightforward implementation of the |
256 |
> |
* iterator interface, relying on the backing list's {@code size()}, |
257 |
> |
* {@code get(int)}, and {@code remove(int)} methods. |
258 |
> |
* |
259 |
> |
* <p>Note that the iterator returned by this method will throw an |
260 |
> |
* {@code UnsupportedOperationException} in response to its |
261 |
> |
* {@code remove} method unless the list's {@code remove(int)} method is |
262 |
> |
* overridden. |
263 |
> |
* |
264 |
> |
* <p>This implementation can be made to throw runtime exceptions in the |
265 |
> |
* face of concurrent modification, as described in the specification |
266 |
> |
* for the (protected) {@code modCount} field. |
267 |
|
* |
268 |
|
* @return an iterator over the elements in this list in proper sequence |
269 |
|
* |
276 |
|
/** |
277 |
|
* {@inheritDoc} |
278 |
|
* |
279 |
< |
* <p>This implementation returns <tt>listIterator(0)</tt>. |
279 |
> |
* <p>This implementation returns {@code listIterator(0)}. |
280 |
|
* |
281 |
|
* @see #listIterator(int) |
282 |
|
*/ |
288 |
|
* {@inheritDoc} |
289 |
|
* |
290 |
|
* <p>This implementation returns a straightforward implementation of the |
291 |
< |
* <tt>ListIterator</tt> interface that extends the implementation of the |
292 |
< |
* <tt>Iterator</tt> interface returned by the <tt>iterator()</tt> method. |
293 |
< |
* The <tt>ListIterator</tt> implementation relies on the backing list's |
294 |
< |
* <tt>get(int)</tt>, <tt>set(int, Object)</tt>, <tt>add(int, Object)</tt> |
295 |
< |
* and <tt>remove(int)</tt> methods. |
291 |
> |
* {@code ListIterator} interface that extends the implementation of the |
292 |
> |
* {@code Iterator} interface returned by the {@code iterator()} method. |
293 |
> |
* The {@code ListIterator} implementation relies on the backing list's |
294 |
> |
* {@code get(int)}, {@code set(int, E)}, {@code add(int, E)} |
295 |
> |
* and {@code remove(int)} methods. |
296 |
|
* |
297 |
|
* <p>Note that the list iterator returned by this implementation will |
298 |
< |
* throw an <tt>UnsupportedOperationException</tt> in response to its |
299 |
< |
* <tt>remove</tt>, <tt>set</tt> and <tt>add</tt> methods unless the |
300 |
< |
* list's <tt>remove(int)</tt>, <tt>set(int, Object)</tt>, and |
301 |
< |
* <tt>add(int, Object)</tt> methods are overridden. |
298 |
> |
* throw an {@code UnsupportedOperationException} in response to its |
299 |
> |
* {@code remove}, {@code set} and {@code add} methods unless the |
300 |
> |
* list's {@code remove(int)}, {@code set(int, E)}, and |
301 |
> |
* {@code add(int, E)} methods are overridden. |
302 |
|
* |
303 |
|
* <p>This implementation can be made to throw runtime exceptions in the |
304 |
|
* face of concurrent modification, as described in the specification for |
305 |
< |
* the (protected) <tt>modCount</tt> field. |
305 |
> |
* the (protected) {@code modCount} field. |
306 |
|
* |
307 |
|
* @throws IndexOutOfBoundsException {@inheritDoc} |
308 |
|
* |
340 |
|
} |
341 |
|
|
342 |
|
public E next() { |
343 |
< |
try { |
344 |
< |
int i = cursor; |
345 |
< |
E next = get(i); |
346 |
< |
lastRet = i; |
347 |
< |
cursor = i + 1; |
348 |
< |
return next; |
349 |
< |
} catch (IndexOutOfBoundsException ex) { |
350 |
< |
throw new NoSuchElementException(); |
351 |
< |
} finally { |
354 |
< |
if (expectedModCount != modCount) |
355 |
< |
throw new ConcurrentModificationException(); |
356 |
< |
} |
343 |
> |
checkForComodification(); |
344 |
> |
try { |
345 |
> |
E next = get(cursor); |
346 |
> |
lastRet = cursor++; |
347 |
> |
return next; |
348 |
> |
} catch (IndexOutOfBoundsException e) { |
349 |
> |
checkForComodification(); |
350 |
> |
throw new NoSuchElementException(); |
351 |
> |
} |
352 |
|
} |
353 |
|
|
354 |
|
public void remove() { |
355 |
|
if (lastRet == -1) |
356 |
|
throw new IllegalStateException(); |
357 |
< |
if (expectedModCount != modCount) |
358 |
< |
throw new ConcurrentModificationException(); |
357 |
> |
checkForComodification(); |
358 |
> |
|
359 |
|
try { |
360 |
|
AbstractList.this.remove(lastRet); |
361 |
|
if (lastRet < cursor) |
366 |
|
throw new ConcurrentModificationException(); |
367 |
|
} |
368 |
|
} |
369 |
+ |
|
370 |
+ |
final void checkForComodification() { |
371 |
+ |
if (modCount != expectedModCount) |
372 |
+ |
throw new ConcurrentModificationException(); |
373 |
+ |
} |
374 |
|
} |
375 |
|
|
376 |
|
private class ListItr extends Itr implements ListIterator<E> { |
382 |
|
return cursor != 0; |
383 |
|
} |
384 |
|
|
385 |
– |
public int nextIndex() { |
386 |
– |
return cursor; |
387 |
– |
} |
388 |
– |
|
389 |
– |
public int previousIndex() { |
390 |
– |
return cursor - 1; |
391 |
– |
} |
392 |
– |
|
385 |
|
public E previous() { |
386 |
+ |
checkForComodification(); |
387 |
|
try { |
388 |
|
int i = cursor - 1; |
389 |
< |
E prev = get(i); |
390 |
< |
lastRet = i; |
391 |
< |
cursor = i; |
392 |
< |
return prev; |
393 |
< |
} catch (IndexOutOfBoundsException ex) { |
389 |
> |
E previous = get(i); |
390 |
> |
lastRet = cursor = i; |
391 |
> |
return previous; |
392 |
> |
} catch (IndexOutOfBoundsException e) { |
393 |
> |
checkForComodification(); |
394 |
|
throw new NoSuchElementException(); |
402 |
– |
} finally { |
403 |
– |
if (expectedModCount != modCount) |
404 |
– |
throw new ConcurrentModificationException(); |
395 |
|
} |
396 |
|
} |
397 |
|
|
398 |
+ |
public int nextIndex() { |
399 |
+ |
return cursor; |
400 |
+ |
} |
401 |
+ |
|
402 |
+ |
public int previousIndex() { |
403 |
+ |
return cursor-1; |
404 |
+ |
} |
405 |
+ |
|
406 |
|
public void set(E e) { |
407 |
|
if (lastRet == -1) |
408 |
|
throw new IllegalStateException(); |
409 |
< |
if (expectedModCount != modCount) |
410 |
< |
throw new ConcurrentModificationException(); |
409 |
> |
checkForComodification(); |
410 |
> |
|
411 |
|
try { |
412 |
|
AbstractList.this.set(lastRet, e); |
413 |
|
expectedModCount = modCount; |
417 |
|
} |
418 |
|
|
419 |
|
public void add(E e) { |
420 |
< |
if (expectedModCount != modCount) |
421 |
< |
throw new ConcurrentModificationException(); |
420 |
> |
checkForComodification(); |
421 |
> |
|
422 |
|
try { |
423 |
|
int i = cursor; |
424 |
|
AbstractList.this.add(i, e); |
435 |
|
* {@inheritDoc} |
436 |
|
* |
437 |
|
* <p>This implementation returns a list that subclasses |
438 |
< |
* <tt>AbstractList</tt>. The subclass stores, in private fields, the |
438 |
> |
* {@code AbstractList}. The subclass stores, in private fields, the |
439 |
|
* offset of the subList within the backing list, the size of the subList |
440 |
|
* (which can change over its lifetime), and the expected |
441 |
< |
* <tt>modCount</tt> value of the backing list. There are two variants |
442 |
< |
* of the subclass, one of which implements <tt>RandomAccess</tt>. |
443 |
< |
* If this list implements <tt>RandomAccess</tt> the returned list will |
444 |
< |
* be an instance of the subclass that implements <tt>RandomAccess</tt>. |
445 |
< |
* |
446 |
< |
* <p>The subclass's <tt>set(int, Object)</tt>, <tt>get(int)</tt>, |
447 |
< |
* <tt>add(int, Object)</tt>, <tt>remove(int)</tt>, <tt>addAll(int, |
448 |
< |
* Collection)</tt> and <tt>removeRange(int, int)</tt> methods all |
441 |
> |
* {@code modCount} value of the backing list. There are two variants |
442 |
> |
* of the subclass, one of which implements {@code RandomAccess}. |
443 |
> |
* If this list implements {@code RandomAccess} the returned list will |
444 |
> |
* be an instance of the subclass that implements {@code RandomAccess}. |
445 |
> |
* |
446 |
> |
* <p>The subclass's {@code set(int, E)}, {@code get(int)}, |
447 |
> |
* {@code add(int, E)}, {@code remove(int)}, {@code addAll(int, |
448 |
> |
* Collection)} and {@code removeRange(int, int)} methods all |
449 |
|
* delegate to the corresponding methods on the backing abstract list, |
450 |
|
* after bounds-checking the index and adjusting for the offset. The |
451 |
< |
* <tt>addAll(Collection c)</tt> method merely returns <tt>addAll(size, |
452 |
< |
* c)</tt>. |
451 |
> |
* {@code addAll(Collection c)} method merely returns {@code addAll(size, |
452 |
> |
* c)}. |
453 |
|
* |
454 |
< |
* <p>The <tt>listIterator(int)</tt> method returns a "wrapper object" |
454 |
> |
* <p>The {@code listIterator(int)} method returns a "wrapper object" |
455 |
|
* over a list iterator on the backing list, which is created with the |
456 |
< |
* corresponding method on the backing list. The <tt>iterator</tt> method |
457 |
< |
* merely returns <tt>listIterator()</tt>, and the <tt>size</tt> method |
458 |
< |
* merely returns the subclass's <tt>size</tt> field. |
456 |
> |
* corresponding method on the backing list. The {@code iterator} method |
457 |
> |
* merely returns {@code listIterator()}, and the {@code size} method |
458 |
> |
* merely returns the subclass's {@code size} field. |
459 |
|
* |
460 |
< |
* <p>All methods first check to see if the actual <tt>modCount</tt> of |
460 |
> |
* <p>All methods first check to see if the actual {@code modCount} of |
461 |
|
* the backing list is equal to its expected value, and throw a |
462 |
< |
* <tt>ConcurrentModificationException</tt> if it is not. |
462 |
> |
* {@code ConcurrentModificationException} if it is not. |
463 |
|
* |
464 |
|
* @throws IndexOutOfBoundsException endpoint index value out of range |
465 |
< |
* <tt>(fromIndex < 0 || toIndex > size)</tt> |
465 |
> |
* {@code (fromIndex < 0 || toIndex > size)} |
466 |
|
* @throws IllegalArgumentException if the endpoint indices are out of order |
467 |
< |
* <tt>(fromIndex > toIndex)</tt> |
467 |
> |
* {@code (fromIndex > toIndex)} |
468 |
|
*/ |
469 |
|
public List<E> subList(int fromIndex, int toIndex) { |
470 |
|
return (this instanceof RandomAccess ? |
471 |
< |
new RandomAccessSubList<E>(this, fromIndex, toIndex) : |
472 |
< |
new SubList<E>(this, fromIndex, toIndex)); |
471 |
> |
new RandomAccessSubList(this, this, fromIndex, fromIndex, toIndex) : |
472 |
> |
new SubList(this, this, fromIndex, fromIndex, toIndex)); |
473 |
|
} |
474 |
|
|
475 |
|
// Comparison and hashing |
476 |
|
|
477 |
|
/** |
478 |
|
* Compares the specified object with this list for equality. Returns |
479 |
< |
* <tt>true</tt> if and only if the specified object is also a list, both |
479 |
> |
* {@code true} if and only if the specified object is also a list, both |
480 |
|
* lists have the same size, and all corresponding pairs of elements in |
481 |
< |
* the two lists are <i>equal</i>. (Two elements <tt>e1</tt> and |
482 |
< |
* <tt>e2</tt> are <i>equal</i> if <tt>(e1==null ? e2==null : |
483 |
< |
* e1.equals(e2))</tt>.) In other words, two lists are defined to be |
484 |
< |
* equal if they contain the same elements in the same order.<p> |
485 |
< |
* |
486 |
< |
* This implementation first checks if the specified object is this |
487 |
< |
* list. If so, it returns <tt>true</tt>; if not, it checks if the |
488 |
< |
* specified object is a list. If not, it returns <tt>false</tt>; if so, |
481 |
> |
* the two lists are <i>equal</i>. (Two elements {@code e1} and |
482 |
> |
* {@code e2} are <i>equal</i> if {@code (e1==null ? e2==null : |
483 |
> |
* e1.equals(e2))}.) In other words, two lists are defined to be |
484 |
> |
* equal if they contain the same elements in the same order. |
485 |
> |
* |
486 |
> |
* <p>This implementation first checks if the specified object is this |
487 |
> |
* list. If so, it returns {@code true}; if not, it checks if the |
488 |
> |
* specified object is a list. If not, it returns {@code false}; if so, |
489 |
|
* it iterates over both lists, comparing corresponding pairs of elements. |
490 |
< |
* If any comparison returns <tt>false</tt>, this method returns |
491 |
< |
* <tt>false</tt>. If either iterator runs out of elements before the |
492 |
< |
* other it returns <tt>false</tt> (as the lists are of unequal length); |
493 |
< |
* otherwise it returns <tt>true</tt> when the iterations complete. |
490 |
> |
* If any comparison returns {@code false}, this method returns |
491 |
> |
* {@code false}. If either iterator runs out of elements before the |
492 |
> |
* other it returns {@code false} (as the lists are of unequal length); |
493 |
> |
* otherwise it returns {@code true} when the iterations complete. |
494 |
|
* |
495 |
|
* @param o the object to be compared for equality with this list |
496 |
< |
* @return <tt>true</tt> if the specified object is equal to this list |
496 |
> |
* @return {@code true} if the specified object is equal to this list |
497 |
|
*/ |
498 |
|
public boolean equals(Object o) { |
499 |
|
if (o == this) |
513 |
|
} |
514 |
|
|
515 |
|
/** |
516 |
< |
* Returns the hash code value for this list. <p> |
516 |
> |
* Returns the hash code value for this list. |
517 |
|
* |
518 |
< |
* This implementation uses exactly the code that is used to define the |
518 |
> |
* <p>This implementation uses exactly the code that is used to define the |
519 |
|
* list hash function in the documentation for the {@link List#hashCode} |
520 |
|
* method. |
521 |
|
* |
533 |
|
|
534 |
|
/** |
535 |
|
* Removes from this list all of the elements whose index is between |
536 |
< |
* <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive. |
536 |
> |
* {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. |
537 |
|
* Shifts any succeeding elements to the left (reduces their index). |
538 |
< |
* This call shortens the ArrayList by <tt>(toIndex - fromIndex)</tt> |
539 |
< |
* elements. (If <tt>toIndex==fromIndex</tt>, this operation has no |
540 |
< |
* effect.)<p> |
538 |
> |
* This call shortens the ArrayList by {@code (toIndex - fromIndex)} |
539 |
> |
* elements. (If {@code toIndex==fromIndex}, this operation has no |
540 |
> |
* effect.) |
541 |
|
* |
542 |
< |
* This method is called by the <tt>clear</tt> operation on this list |
542 |
> |
* <p>This method is called by the {@code clear} operation on this list |
543 |
|
* and its subLists. Overriding this method to take advantage of |
544 |
|
* the internals of the list implementation can <i>substantially</i> |
545 |
< |
* improve the performance of the <tt>clear</tt> operation on this list |
546 |
< |
* and its subLists.<p> |
545 |
> |
* improve the performance of the {@code clear} operation on this list |
546 |
> |
* and its subLists. |
547 |
|
* |
548 |
< |
* This implementation gets a list iterator positioned before |
549 |
< |
* <tt>fromIndex</tt>, and repeatedly calls <tt>ListIterator.next</tt> |
550 |
< |
* followed by <tt>ListIterator.remove</tt> until the entire range has |
551 |
< |
* been removed. <b>Note: if <tt>ListIterator.remove</tt> requires linear |
548 |
> |
* <p>This implementation gets a list iterator positioned before |
549 |
> |
* {@code fromIndex}, and repeatedly calls {@code ListIterator.next} |
550 |
> |
* followed by {@code ListIterator.remove} until the entire range has |
551 |
> |
* been removed. <b>Note: if {@code ListIterator.remove} requires linear |
552 |
|
* time, this implementation requires quadratic time.</b> |
553 |
|
* |
554 |
|
* @param fromIndex index of first element to be removed |
566 |
|
* The number of times this list has been <i>structurally modified</i>. |
567 |
|
* Structural modifications are those that change the size of the |
568 |
|
* list, or otherwise perturb it in such a fashion that iterations in |
569 |
< |
* progress may yield incorrect results.<p> |
569 |
> |
* progress may yield incorrect results. |
570 |
|
* |
571 |
< |
* This field is used by the iterator and list iterator implementation |
572 |
< |
* returned by the <tt>iterator</tt> and <tt>listIterator</tt> methods. |
571 |
> |
* <p>This field is used by the iterator and list iterator implementation |
572 |
> |
* returned by the {@code iterator} and {@code listIterator} methods. |
573 |
|
* If the value of this field changes unexpectedly, the iterator (or list |
574 |
< |
* iterator) will throw a <tt>ConcurrentModificationException</tt> in |
575 |
< |
* response to the <tt>next</tt>, <tt>remove</tt>, <tt>previous</tt>, |
576 |
< |
* <tt>set</tt> or <tt>add</tt> operations. This provides |
574 |
> |
* iterator) will throw a {@code ConcurrentModificationException} in |
575 |
> |
* response to the {@code next}, {@code remove}, {@code previous}, |
576 |
> |
* {@code set} or {@code add} operations. This provides |
577 |
|
* <i>fail-fast</i> behavior, rather than non-deterministic behavior in |
578 |
< |
* the face of concurrent modification during iteration.<p> |
578 |
> |
* the face of concurrent modification during iteration. |
579 |
|
* |
580 |
< |
* <b>Use of this field by subclasses is optional.</b> If a subclass |
580 |
> |
* <p><b>Use of this field by subclasses is optional.</b> If a subclass |
581 |
|
* wishes to provide fail-fast iterators (and list iterators), then it |
582 |
< |
* merely has to increment this field in its <tt>add(int, Object)</tt> and |
583 |
< |
* <tt>remove(int)</tt> methods (and any other methods that it overrides |
582 |
> |
* merely has to increment this field in its {@code add(int, E)} and |
583 |
> |
* {@code remove(int)} methods (and any other methods that it overrides |
584 |
|
* that result in structural modifications to the list). A single call to |
585 |
< |
* <tt>add(int, Object)</tt> or <tt>remove(int)</tt> must add no more than |
585 |
> |
* {@code add(int, E)} or {@code remove(int)} must add no more than |
586 |
|
* one to this field, or the iterators (and list iterators) will throw |
587 |
< |
* bogus <tt>ConcurrentModificationExceptions</tt>. If an implementation |
587 |
> |
* bogus {@code ConcurrentModificationExceptions}. If an implementation |
588 |
|
* does not wish to provide fail-fast iterators, this field may be |
589 |
|
* ignored. |
590 |
|
*/ |
591 |
|
protected transient int modCount = 0; |
592 |
|
} |
593 |
|
|
594 |
+ |
/** |
595 |
+ |
* Generic sublists. Non-nested to enable construction by other |
596 |
+ |
* classes in this package. |
597 |
+ |
*/ |
598 |
|
class SubList<E> extends AbstractList<E> { |
599 |
< |
private AbstractList<E> l; |
600 |
< |
private int offset; |
601 |
< |
private int size; |
602 |
< |
private int expectedModCount; |
603 |
< |
|
604 |
< |
SubList(AbstractList<E> list, int fromIndex, int toIndex) { |
599 |
> |
/* |
600 |
> |
* A SubList has both a "base", the ultimate backing list, as well |
601 |
> |
* as a "parent", which is the list or sublist creating this |
602 |
> |
* sublist. All methods that may cause structural modifications |
603 |
> |
* must propagate through the parent link, with O(k) performance |
604 |
> |
* where k is sublist depth. For example in the case of a |
605 |
> |
* sub-sub-list, invoking remove(x) will result in a chain of |
606 |
> |
* three remove calls. However, all other non-structurally |
607 |
> |
* modifying methods can bypass this chain, and relay directly to |
608 |
> |
* the base list. In particular, doing so signficantly speeds up |
609 |
> |
* the performance of iterators for deeply-nested sublists. |
610 |
> |
*/ |
611 |
> |
final AbstractList<E> base; // Backing list |
612 |
> |
final AbstractList<E> parent; // Parent list |
613 |
> |
final int baseOffset; // index wrt base |
614 |
> |
final int parentOffset; // index wrt parent |
615 |
> |
int length; // Number of elements in this sublist |
616 |
> |
|
617 |
> |
SubList(AbstractList<E> base, |
618 |
> |
AbstractList<E> parent, |
619 |
> |
int baseIndex, |
620 |
> |
int fromIndex, |
621 |
> |
int toIndex) { |
622 |
|
if (fromIndex < 0) |
623 |
|
throw new IndexOutOfBoundsException("fromIndex = " + fromIndex); |
624 |
< |
if (toIndex > list.size()) |
624 |
> |
if (toIndex > parent.size()) |
625 |
|
throw new IndexOutOfBoundsException("toIndex = " + toIndex); |
626 |
|
if (fromIndex > toIndex) |
627 |
|
throw new IllegalArgumentException("fromIndex(" + fromIndex + |
628 |
|
") > toIndex(" + toIndex + ")"); |
629 |
< |
l = list; |
630 |
< |
offset = fromIndex; |
631 |
< |
size = toIndex - fromIndex; |
632 |
< |
expectedModCount = l.modCount; |
629 |
> |
this.base = base; |
630 |
> |
this.parent = parent; |
631 |
> |
this.baseOffset = baseIndex; |
632 |
> |
this.parentOffset = fromIndex; |
633 |
> |
this.length = toIndex - fromIndex; |
634 |
> |
this.modCount = base.modCount; |
635 |
> |
} |
636 |
> |
|
637 |
> |
/** |
638 |
> |
* Returns an IndexOutOfBoundsException with nicer message |
639 |
> |
*/ |
640 |
> |
private IndexOutOfBoundsException indexError(int index) { |
641 |
> |
return new IndexOutOfBoundsException("Index: " + index + |
642 |
> |
", Size: " + length); |
643 |
|
} |
644 |
|
|
645 |
|
public E set(int index, E element) { |
646 |
< |
rangeCheck(index); |
647 |
< |
checkForComodification(); |
648 |
< |
return l.set(index+offset, element); |
646 |
> |
if (index < 0 || index >= length) |
647 |
> |
throw indexError(index); |
648 |
> |
if (base.modCount != modCount) |
649 |
> |
throw new ConcurrentModificationException(); |
650 |
> |
return base.set(index + baseOffset, element); |
651 |
|
} |
652 |
|
|
653 |
|
public E get(int index) { |
654 |
< |
rangeCheck(index); |
655 |
< |
checkForComodification(); |
656 |
< |
return l.get(index+offset); |
654 |
> |
if (index < 0 || index >= length) |
655 |
> |
throw indexError(index); |
656 |
> |
if (base.modCount != modCount) |
657 |
> |
throw new ConcurrentModificationException(); |
658 |
> |
return base.get(index + baseOffset); |
659 |
|
} |
660 |
|
|
661 |
|
public int size() { |
662 |
< |
checkForComodification(); |
663 |
< |
return size; |
662 |
> |
if (base.modCount != modCount) |
663 |
> |
throw new ConcurrentModificationException(); |
664 |
> |
return length; |
665 |
|
} |
666 |
|
|
667 |
|
public void add(int index, E element) { |
668 |
< |
if (index<0 || index>size) |
669 |
< |
throw new IndexOutOfBoundsException(); |
670 |
< |
checkForComodification(); |
671 |
< |
l.add(index+offset, element); |
672 |
< |
expectedModCount = l.modCount; |
673 |
< |
size++; |
674 |
< |
modCount++; |
668 |
> |
if (index < 0 || index>length) |
669 |
> |
throw indexError(index); |
670 |
> |
if (base.modCount != modCount) |
671 |
> |
throw new ConcurrentModificationException(); |
672 |
> |
parent.add(index + parentOffset, element); |
673 |
> |
length++; |
674 |
> |
modCount = base.modCount; |
675 |
|
} |
676 |
|
|
677 |
|
public E remove(int index) { |
678 |
< |
rangeCheck(index); |
679 |
< |
checkForComodification(); |
680 |
< |
E result = l.remove(index+offset); |
681 |
< |
expectedModCount = l.modCount; |
682 |
< |
size--; |
683 |
< |
modCount++; |
678 |
> |
if (index < 0 || index >= length) |
679 |
> |
throw indexError(index); |
680 |
> |
if (base.modCount != modCount) |
681 |
> |
throw new ConcurrentModificationException(); |
682 |
> |
E result = parent.remove(index + parentOffset); |
683 |
> |
length--; |
684 |
> |
modCount = base.modCount; |
685 |
|
return result; |
686 |
|
} |
687 |
|
|
688 |
|
protected void removeRange(int fromIndex, int toIndex) { |
689 |
< |
checkForComodification(); |
690 |
< |
l.removeRange(fromIndex+offset, toIndex+offset); |
691 |
< |
expectedModCount = l.modCount; |
692 |
< |
size -= (toIndex-fromIndex); |
693 |
< |
modCount++; |
689 |
> |
if (base.modCount != modCount) |
690 |
> |
throw new ConcurrentModificationException(); |
691 |
> |
parent.removeRange(fromIndex + parentOffset, toIndex + parentOffset); |
692 |
> |
length -= (toIndex-fromIndex); |
693 |
> |
modCount = base.modCount; |
694 |
|
} |
695 |
|
|
696 |
|
public boolean addAll(Collection<? extends E> c) { |
697 |
< |
return addAll(size, c); |
697 |
> |
return addAll(length, c); |
698 |
|
} |
699 |
|
|
700 |
|
public boolean addAll(int index, Collection<? extends E> c) { |
701 |
< |
if (index<0 || index>size) |
702 |
< |
throw new IndexOutOfBoundsException( |
668 |
< |
"Index: "+index+", Size: "+size); |
701 |
> |
if (index < 0 || index > length) |
702 |
> |
throw indexError(index); |
703 |
|
int cSize = c.size(); |
704 |
|
if (cSize==0) |
705 |
|
return false; |
706 |
|
|
707 |
< |
checkForComodification(); |
708 |
< |
l.addAll(offset+index, c); |
709 |
< |
expectedModCount = l.modCount; |
710 |
< |
size += cSize; |
711 |
< |
modCount++; |
707 |
> |
if (base.modCount != modCount) |
708 |
> |
throw new ConcurrentModificationException(); |
709 |
> |
parent.addAll(parentOffset + index, c); |
710 |
> |
length += cSize; |
711 |
> |
modCount = base.modCount; |
712 |
|
return true; |
713 |
|
} |
714 |
|
|
715 |
+ |
public List<E> subList(int fromIndex, int toIndex) { |
716 |
+ |
return new SubList(base, this, fromIndex + baseOffset, |
717 |
+ |
fromIndex, toIndex); |
718 |
+ |
} |
719 |
+ |
|
720 |
|
public Iterator<E> iterator() { |
721 |
< |
return listIterator(); |
721 |
> |
return new SubListIterator(this, 0); |
722 |
|
} |
723 |
|
|
724 |
< |
public ListIterator<E> listIterator(final int index) { |
725 |
< |
checkForComodification(); |
726 |
< |
if (index<0 || index>size) |
688 |
< |
throw new IndexOutOfBoundsException( |
689 |
< |
"Index: "+index+", Size: "+size); |
724 |
> |
public ListIterator<E> listIterator() { |
725 |
> |
return new SubListIterator(this, 0); |
726 |
> |
} |
727 |
|
|
728 |
< |
return new ListIterator<E>() { |
729 |
< |
private ListIterator<E> i = l.listIterator(index+offset); |
728 |
> |
public ListIterator<E> listIterator(int index) { |
729 |
> |
if (index < 0 || index>length) |
730 |
> |
throw indexError(index); |
731 |
> |
return new SubListIterator(this, index); |
732 |
> |
} |
733 |
|
|
734 |
< |
public boolean hasNext() { |
735 |
< |
return nextIndex() < size; |
736 |
< |
} |
734 |
> |
/** |
735 |
> |
* Generic sublist iterator obeying fastfail semantics via |
736 |
> |
* modCount. The hasNext and next methods locally check for |
737 |
> |
* in-range indices before relaying to backing list to get |
738 |
> |
* element. If this either encounters an unexpected modCount or |
739 |
> |
* fails, the backing list must have been concurrently modified, |
740 |
> |
* and is so reported. The add and remove methods performing |
741 |
> |
* structural modifications instead relay them through the |
742 |
> |
* sublist. |
743 |
> |
*/ |
744 |
> |
private static final class SubListIterator<E> implements ListIterator<E> { |
745 |
> |
final SubList<E> outer; // Sublist creating this iteraor |
746 |
> |
final AbstractList<E> base; // base list |
747 |
> |
final int offset; // Cursor offset wrt base |
748 |
> |
int cursor; // Current index |
749 |
> |
int fence; // Upper bound on cursor |
750 |
> |
int lastRet; // Index of returned element, or -1 |
751 |
> |
int expectedModCount; // Expected modCount of base |
752 |
> |
|
753 |
> |
SubListIterator(SubList<E> list, int index) { |
754 |
> |
this.lastRet = -1; |
755 |
> |
this.cursor = index; |
756 |
> |
this.outer = list; |
757 |
> |
this.offset = list.baseOffset; |
758 |
> |
this.fence = list.length; |
759 |
> |
this.base = list.base; |
760 |
> |
this.expectedModCount = base.modCount; |
761 |
> |
} |
762 |
|
|
763 |
< |
public E next() { |
764 |
< |
if (hasNext()) |
765 |
< |
return i.next(); |
701 |
< |
else |
702 |
< |
throw new NoSuchElementException(); |
703 |
< |
} |
763 |
> |
public boolean hasNext() { |
764 |
> |
return cursor < fence; |
765 |
> |
} |
766 |
|
|
767 |
< |
public boolean hasPrevious() { |
768 |
< |
return previousIndex() >= 0; |
769 |
< |
} |
767 |
> |
public boolean hasPrevious() { |
768 |
> |
return cursor > 0; |
769 |
> |
} |
770 |
|
|
771 |
< |
public E previous() { |
772 |
< |
if (hasPrevious()) |
773 |
< |
return i.previous(); |
712 |
< |
else |
713 |
< |
throw new NoSuchElementException(); |
714 |
< |
} |
771 |
> |
public int nextIndex() { |
772 |
> |
return cursor; |
773 |
> |
} |
774 |
|
|
775 |
< |
public int nextIndex() { |
776 |
< |
return i.nextIndex() - offset; |
777 |
< |
} |
775 |
> |
public int previousIndex() { |
776 |
> |
return cursor - 1; |
777 |
> |
} |
778 |
|
|
779 |
< |
public int previousIndex() { |
780 |
< |
return i.previousIndex() - offset; |
779 |
> |
public E next() { |
780 |
> |
int i = cursor; |
781 |
> |
if (cursor >= fence) |
782 |
> |
throw new NoSuchElementException(); |
783 |
> |
if (expectedModCount == base.modCount) { |
784 |
> |
try { |
785 |
> |
Object next = base.get(i + offset); |
786 |
> |
lastRet = i; |
787 |
> |
cursor = i + 1; |
788 |
> |
return (E)next; |
789 |
> |
} catch (IndexOutOfBoundsException fallThrough) { |
790 |
> |
} |
791 |
|
} |
792 |
+ |
throw new ConcurrentModificationException(); |
793 |
+ |
} |
794 |
|
|
795 |
< |
public void remove() { |
796 |
< |
i.remove(); |
797 |
< |
expectedModCount = l.modCount; |
798 |
< |
size--; |
799 |
< |
modCount++; |
795 |
> |
public E previous() { |
796 |
> |
int i = cursor - 1; |
797 |
> |
if (i < 0) |
798 |
> |
throw new NoSuchElementException(); |
799 |
> |
if (expectedModCount == base.modCount) { |
800 |
> |
try { |
801 |
> |
Object prev = base.get(i + offset); |
802 |
> |
lastRet = i; |
803 |
> |
cursor = i; |
804 |
> |
return (E)prev; |
805 |
> |
} catch (IndexOutOfBoundsException fallThrough) { |
806 |
> |
} |
807 |
|
} |
808 |
+ |
throw new ConcurrentModificationException(); |
809 |
+ |
} |
810 |
|
|
811 |
< |
public void set(E e) { |
812 |
< |
i.set(e); |
811 |
> |
public void set(E e) { |
812 |
> |
if (lastRet < 0) |
813 |
> |
throw new IllegalStateException(); |
814 |
> |
if (expectedModCount != base.modCount) |
815 |
> |
throw new ConcurrentModificationException(); |
816 |
> |
try { |
817 |
> |
outer.set(lastRet, e); |
818 |
> |
expectedModCount = base.modCount; |
819 |
> |
} catch (IndexOutOfBoundsException ex) { |
820 |
> |
throw new ConcurrentModificationException(); |
821 |
|
} |
822 |
+ |
} |
823 |
|
|
824 |
< |
public void add(E e) { |
825 |
< |
i.add(e); |
826 |
< |
expectedModCount = l.modCount; |
827 |
< |
size++; |
828 |
< |
modCount++; |
824 |
> |
public void remove() { |
825 |
> |
int i = lastRet; |
826 |
> |
if (i < 0) |
827 |
> |
throw new IllegalStateException(); |
828 |
> |
if (expectedModCount != base.modCount) |
829 |
> |
throw new ConcurrentModificationException(); |
830 |
> |
try { |
831 |
> |
outer.remove(i); |
832 |
> |
if (i < cursor) |
833 |
> |
cursor--; |
834 |
> |
lastRet = -1; |
835 |
> |
fence = outer.length; |
836 |
> |
expectedModCount = base.modCount; |
837 |
> |
} catch (IndexOutOfBoundsException ex) { |
838 |
> |
throw new ConcurrentModificationException(); |
839 |
|
} |
840 |
< |
}; |
742 |
< |
} |
743 |
< |
|
744 |
< |
public List<E> subList(int fromIndex, int toIndex) { |
745 |
< |
return new SubList<E>(this, fromIndex, toIndex); |
746 |
< |
} |
840 |
> |
} |
841 |
|
|
842 |
< |
private void rangeCheck(int index) { |
843 |
< |
if (index<0 || index>=size) |
844 |
< |
throw new IndexOutOfBoundsException("Index: "+index+ |
845 |
< |
",Size: "+size); |
842 |
> |
public void add(E e) { |
843 |
> |
if (expectedModCount != base.modCount) |
844 |
> |
throw new ConcurrentModificationException(); |
845 |
> |
try { |
846 |
> |
int i = cursor; |
847 |
> |
outer.add(i, e); |
848 |
> |
cursor = i + 1; |
849 |
> |
lastRet = -1; |
850 |
> |
fence = outer.length; |
851 |
> |
expectedModCount = base.modCount; |
852 |
> |
} catch (IndexOutOfBoundsException ex) { |
853 |
> |
throw new ConcurrentModificationException(); |
854 |
> |
} |
855 |
> |
} |
856 |
|
} |
857 |
|
|
754 |
– |
private void checkForComodification() { |
755 |
– |
if (l.modCount != expectedModCount) |
756 |
– |
throw new ConcurrentModificationException(); |
757 |
– |
} |
858 |
|
} |
859 |
|
|
860 |
|
class RandomAccessSubList<E> extends SubList<E> implements RandomAccess { |
861 |
< |
RandomAccessSubList(AbstractList<E> list, int fromIndex, int toIndex) { |
862 |
< |
super(list, fromIndex, toIndex); |
861 |
> |
RandomAccessSubList(AbstractList<E> base, |
862 |
> |
AbstractList<E> parent, int baseIndex, |
863 |
> |
int fromIndex, int toIndex) { |
864 |
> |
super(base, parent, baseIndex, fromIndex, toIndex); |
865 |
|
} |
866 |
|
|
867 |
|
public List<E> subList(int fromIndex, int toIndex) { |
868 |
< |
return new RandomAccessSubList<E>(this, fromIndex, toIndex); |
868 |
> |
return new RandomAccessSubList(base, this, fromIndex + baseOffset, |
869 |
> |
fromIndex, toIndex); |
870 |
|
} |
871 |
|
} |