1 |
/* |
2 |
* %W% %E% |
3 |
* |
4 |
* Copyright 2006 Sun Microsystems, Inc. All rights reserved. |
5 |
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
6 |
*/ |
7 |
|
8 |
package java.util; |
9 |
import java.util.*; // for javadoc (till 6280605 is fixed) |
10 |
|
11 |
/** |
12 |
* Resizable-array implementation of the <tt>List</tt> interface. Implements |
13 |
* all optional list operations, and permits all elements, including |
14 |
* <tt>null</tt>. In addition to implementing the <tt>List</tt> interface, |
15 |
* this class provides methods to manipulate the size of the array that is |
16 |
* used internally to store the list. (This class is roughly equivalent to |
17 |
* <tt>Vector</tt>, except that it is unsynchronized.)<p> |
18 |
* |
19 |
* The <tt>size</tt>, <tt>isEmpty</tt>, <tt>get</tt>, <tt>set</tt>, |
20 |
* <tt>iterator</tt>, and <tt>listIterator</tt> operations run in constant |
21 |
* time. The <tt>add</tt> operation runs in <i>amortized constant time</i>, |
22 |
* that is, adding n elements requires O(n) time. All of the other operations |
23 |
* run in linear time (roughly speaking). The constant factor is low compared |
24 |
* to that for the <tt>LinkedList</tt> implementation.<p> |
25 |
* |
26 |
* Each <tt>ArrayList</tt> instance has a <i>capacity</i>. The capacity is |
27 |
* the size of the array used to store the elements in the list. It is always |
28 |
* at least as large as the list size. As elements are added to an ArrayList, |
29 |
* its capacity grows automatically. The details of the growth policy are not |
30 |
* specified beyond the fact that adding an element has constant amortized |
31 |
* time cost.<p> |
32 |
* |
33 |
* An application can increase the capacity of an <tt>ArrayList</tt> instance |
34 |
* before adding a large number of elements using the <tt>ensureCapacity</tt> |
35 |
* operation. This may reduce the amount of incremental reallocation. |
36 |
* |
37 |
* <p><strong>Note that this implementation is not synchronized.</strong> |
38 |
* If multiple threads access an <tt>ArrayList</tt> instance concurrently, |
39 |
* and at least one of the threads modifies the list structurally, it |
40 |
* <i>must</i> be synchronized externally. (A structural modification is |
41 |
* any operation that adds or deletes one or more elements, or explicitly |
42 |
* resizes the backing array; merely setting the value of an element is not |
43 |
* a structural modification.) This is typically accomplished by |
44 |
* synchronizing on some object that naturally encapsulates the list. |
45 |
* |
46 |
* If no such object exists, the list should be "wrapped" using the |
47 |
* {@link Collections#synchronizedList Collections.synchronizedList} |
48 |
* method. This is best done at creation time, to prevent accidental |
49 |
* unsynchronized access to the list:<pre> |
50 |
* List list = Collections.synchronizedList(new ArrayList(...));</pre> |
51 |
* |
52 |
* <p>The iterators returned by this class's <tt>iterator</tt> and |
53 |
* <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is |
54 |
* structurally modified at any time after the iterator is created, in any way |
55 |
* except through the iterator's own <tt>remove</tt> or <tt>add</tt> methods, |
56 |
* the iterator will throw a {@link ConcurrentModificationException}. Thus, in |
57 |
* the face of concurrent modification, the iterator fails quickly and cleanly, |
58 |
* rather than risking arbitrary, non-deterministic behavior at an undetermined |
59 |
* time in the future.<p> |
60 |
* |
61 |
* Note that the fail-fast behavior of an iterator cannot be guaranteed |
62 |
* as it is, generally speaking, impossible to make any hard guarantees in the |
63 |
* presence of unsynchronized concurrent modification. Fail-fast iterators |
64 |
* throw <tt>ConcurrentModificationException</tt> on a best-effort basis. |
65 |
* Therefore, it would be wrong to write a program that depended on this |
66 |
* exception for its correctness: <i>the fail-fast behavior of iterators |
67 |
* should be used only to detect bugs.</i><p> |
68 |
* |
69 |
* This class is a member of the |
70 |
* <a href="{@docRoot}/../guide/collections/index.html"> |
71 |
* Java Collections Framework</a>. |
72 |
* |
73 |
* @author Josh Bloch |
74 |
* @author Neal Gafter |
75 |
* @version %I%, %G% |
76 |
* @see Collection |
77 |
* @see List |
78 |
* @see LinkedList |
79 |
* @see Vector |
80 |
* @since 1.2 |
81 |
*/ |
82 |
|
83 |
public class ArrayList<E> extends AbstractList<E> |
84 |
implements List<E>, RandomAccess, Cloneable, java.io.Serializable |
85 |
{ |
86 |
private static final long serialVersionUID = 8683452581122892189L; |
87 |
|
88 |
/** |
89 |
* The array buffer into which the elements of the ArrayList are stored. |
90 |
* The capacity of the ArrayList is the length of this array buffer. |
91 |
*/ |
92 |
private transient Object[] elementData; |
93 |
|
94 |
/** |
95 |
* The size of the ArrayList (the number of elements it contains). |
96 |
* |
97 |
* @serial |
98 |
*/ |
99 |
private int size; |
100 |
|
101 |
/** |
102 |
* Constructs an empty list with the specified initial capacity. |
103 |
* |
104 |
* @param initialCapacity the initial capacity of the list |
105 |
* @throws IllegalArgumentException if the specified initial capacity |
106 |
* is negative |
107 |
*/ |
108 |
public ArrayList(int initialCapacity) { |
109 |
super(); |
110 |
if (initialCapacity < 0) |
111 |
throw new IllegalArgumentException("Illegal Capacity: "+ |
112 |
initialCapacity); |
113 |
this.elementData = new Object[initialCapacity]; |
114 |
} |
115 |
|
116 |
/** |
117 |
* Constructs an empty list with an initial capacity of ten. |
118 |
*/ |
119 |
public ArrayList() { |
120 |
this(10); |
121 |
} |
122 |
|
123 |
/** |
124 |
* Constructs a list containing the elements of the specified |
125 |
* collection, in the order they are returned by the collection's |
126 |
* iterator. The <tt>ArrayList</tt> instance has an initial capacity of |
127 |
* 110% the size of the specified collection. |
128 |
* |
129 |
* @param c the collection whose elements are to be placed into this list |
130 |
* @throws NullPointerException if the specified collection is null |
131 |
*/ |
132 |
public ArrayList(Collection<? extends E> c) { |
133 |
int size = c.size(); |
134 |
// 10% for growth |
135 |
int cap = ((size/10)+1)*11; |
136 |
if (cap > 0) { |
137 |
Object[] a = new Object[cap]; |
138 |
a[size] = a[size+1] = UNALLOCATED; |
139 |
Object[] b = c.toArray(a); |
140 |
if (b[size] == null && b[size+1] == UNALLOCATED) { |
141 |
b[size+1] = null; |
142 |
elementData = b; |
143 |
this.size = size; |
144 |
return; |
145 |
} |
146 |
} |
147 |
initFromConcurrentlyMutating(c); |
148 |
} |
149 |
|
150 |
private void initFromConcurrentlyMutating(Collection<? extends E> c) { |
151 |
elementData = c.toArray(); |
152 |
size = elementData.length; |
153 |
// c.toArray might (incorrectly) not return Object[] (see 6260652) |
154 |
if (elementData.getClass() != Object[].class) |
155 |
elementData = Arrays.copyOf(elementData, size, Object[].class); |
156 |
} |
157 |
|
158 |
private final static Object UNALLOCATED = new Object(); |
159 |
|
160 |
/** |
161 |
* Trims the capacity of this <tt>ArrayList</tt> instance to be the |
162 |
* list's current size. An application can use this operation to minimize |
163 |
* the storage of an <tt>ArrayList</tt> instance. |
164 |
*/ |
165 |
public void trimToSize() { |
166 |
modCount++; |
167 |
int oldCapacity = elementData.length; |
168 |
if (size < oldCapacity) { |
169 |
elementData = Arrays.copyOf(elementData, size); |
170 |
} |
171 |
} |
172 |
|
173 |
/** |
174 |
* Increases the capacity of this <tt>ArrayList</tt> instance, if |
175 |
* necessary, to ensure that it can hold at least the number of elements |
176 |
* specified by the minimum capacity argument. |
177 |
* |
178 |
* @param minCapacity the desired minimum capacity |
179 |
*/ |
180 |
public void ensureCapacity(int minCapacity) { |
181 |
modCount++; |
182 |
if (minCapacity > elementData.length) |
183 |
growArray(minCapacity); |
184 |
} |
185 |
|
186 |
/** |
187 |
* Increases the capacity of the array. |
188 |
* |
189 |
* @param minCapacity the desired minimum capacity |
190 |
*/ |
191 |
private void growArray(int minCapacity) { |
192 |
if (minCapacity < 0) // overflow |
193 |
throw new OutOfMemoryError(); |
194 |
int oldCapacity = elementData.length; |
195 |
// Double size if small; else grow by 50% |
196 |
int newCapacity = ((oldCapacity < 64)? |
197 |
((oldCapacity + 1) * 2): |
198 |
((oldCapacity / 2) * 3)); |
199 |
if (newCapacity < 0) // overflow |
200 |
newCapacity = Integer.MAX_VALUE; |
201 |
if (newCapacity < minCapacity) |
202 |
newCapacity = minCapacity; |
203 |
elementData = Arrays.copyOf(elementData, newCapacity); |
204 |
} |
205 |
|
206 |
/** |
207 |
* Returns the number of elements in this list. |
208 |
* |
209 |
* @return the number of elements in this list |
210 |
*/ |
211 |
public int size() { |
212 |
return size; |
213 |
} |
214 |
|
215 |
/** |
216 |
* Returns <tt>true</tt> if this list contains no elements. |
217 |
* |
218 |
* @return <tt>true</tt> if this list contains no elements |
219 |
*/ |
220 |
public boolean isEmpty() { |
221 |
return size == 0; |
222 |
} |
223 |
|
224 |
/** |
225 |
* Returns <tt>true</tt> if this list contains the specified element. |
226 |
* More formally, returns <tt>true</tt> if and only if this list contains |
227 |
* at least one element <tt>e</tt> such that |
228 |
* <tt>(o==null ? e==null : o.equals(e))</tt>. |
229 |
* |
230 |
* @param o element whose presence in this list is to be tested |
231 |
* @return <tt>true</tt> if this list contains the specified element |
232 |
*/ |
233 |
public boolean contains(Object o) { |
234 |
return indexOf(o) >= 0; |
235 |
} |
236 |
|
237 |
/** |
238 |
* Returns the index of the first occurrence of the specified element |
239 |
* in this list, or -1 if this list does not contain the element. |
240 |
* More formally, returns the lowest index <tt>i</tt> such that |
241 |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, |
242 |
* or -1 if there is no such index. |
243 |
*/ |
244 |
public int indexOf(Object o) { |
245 |
if (o == null) { |
246 |
for (int i = 0; i < size; i++) |
247 |
if (elementData[i]==null) |
248 |
return i; |
249 |
} else { |
250 |
for (int i = 0; i < size; i++) |
251 |
if (o.equals(elementData[i])) |
252 |
return i; |
253 |
} |
254 |
return -1; |
255 |
} |
256 |
|
257 |
/** |
258 |
* Returns the index of the last occurrence of the specified element |
259 |
* in this list, or -1 if this list does not contain the element. |
260 |
* More formally, returns the highest index <tt>i</tt> such that |
261 |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, |
262 |
* or -1 if there is no such index. |
263 |
*/ |
264 |
public int lastIndexOf(Object o) { |
265 |
if (o == null) { |
266 |
for (int i = size-1; i >= 0; i--) |
267 |
if (elementData[i]==null) |
268 |
return i; |
269 |
} else { |
270 |
for (int i = size-1; i >= 0; i--) |
271 |
if (o.equals(elementData[i])) |
272 |
return i; |
273 |
} |
274 |
return -1; |
275 |
} |
276 |
|
277 |
/** |
278 |
* Returns a shallow copy of this <tt>ArrayList</tt> instance. (The |
279 |
* elements themselves are not copied.) |
280 |
* |
281 |
* @return a clone of this <tt>ArrayList</tt> instance |
282 |
*/ |
283 |
public Object clone() { |
284 |
try { |
285 |
ArrayList<E> v = (ArrayList<E>) super.clone(); |
286 |
v.elementData = Arrays.copyOf(elementData, size); |
287 |
v.modCount = 0; |
288 |
return v; |
289 |
} catch (CloneNotSupportedException e) { |
290 |
// this shouldn't happen, since we are Cloneable |
291 |
throw new InternalError(); |
292 |
} |
293 |
} |
294 |
|
295 |
/** |
296 |
* Returns an array containing all of the elements in this list |
297 |
* in proper sequence (from first to last element). |
298 |
* |
299 |
* <p>The returned array will be "safe" in that no references to it are |
300 |
* maintained by this list. (In other words, this method must allocate |
301 |
* a new array). The caller is thus free to modify the returned array. |
302 |
* |
303 |
* <p>This method acts as bridge between array-based and collection-based |
304 |
* APIs. |
305 |
* |
306 |
* @return an array containing all of the elements in this list in |
307 |
* proper sequence |
308 |
*/ |
309 |
public Object[] toArray() { |
310 |
return Arrays.copyOf(elementData, size); |
311 |
} |
312 |
|
313 |
/** |
314 |
* Returns an array containing all of the elements in this list in proper |
315 |
* sequence (from first to last element); the runtime type of the returned |
316 |
* array is that of the specified array. If the list fits in the |
317 |
* specified array, it is returned therein. Otherwise, a new array is |
318 |
* allocated with the runtime type of the specified array and the size of |
319 |
* this list. |
320 |
* |
321 |
* <p>If the list fits in the specified array with room to spare |
322 |
* (i.e., the array has more elements than the list), the element in |
323 |
* the array immediately following the end of the collection is set to |
324 |
* <tt>null</tt>. (This is useful in determining the length of the |
325 |
* list <i>only</i> if the caller knows that the list does not contain |
326 |
* any null elements.) |
327 |
* |
328 |
* @param a the array into which the elements of the list are to |
329 |
* be stored, if it is big enough; otherwise, a new array of the |
330 |
* same runtime type is allocated for this purpose. |
331 |
* @return an array containing the elements of the list |
332 |
* @throws ArrayStoreException if the runtime type of the specified array |
333 |
* is not a supertype of the runtime type of every element in |
334 |
* this list |
335 |
* @throws NullPointerException if the specified array is null |
336 |
*/ |
337 |
public <T> T[] toArray(T[] a) { |
338 |
if (a.length < size) |
339 |
// Make a new array of a's runtime type, but my contents: |
340 |
return (T[]) Arrays.copyOf(elementData, size, a.getClass()); |
341 |
System.arraycopy(elementData, 0, a, 0, size); |
342 |
if (a.length > size) |
343 |
a[size] = null; |
344 |
return a; |
345 |
} |
346 |
|
347 |
// Positional Access Operations |
348 |
|
349 |
/** |
350 |
* Returns error message string for IndexOutOfBoundsExceptions |
351 |
*/ |
352 |
private String ioobe(int index) { |
353 |
return "Index: " + index + ", Size: " + size; |
354 |
} |
355 |
|
356 |
/** |
357 |
* Returns the element at the specified position in this list. |
358 |
* |
359 |
* @param index index of the element to return |
360 |
* @return the element at the specified position in this list |
361 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
362 |
*/ |
363 |
public E get(int index) { |
364 |
if (index >= size) |
365 |
throw new IndexOutOfBoundsException(ioobe(index)); |
366 |
return (E)elementData[index]; |
367 |
} |
368 |
|
369 |
/** |
370 |
* Replaces the element at the specified position in this list with |
371 |
* the specified element. |
372 |
* |
373 |
* @param index index of the element to replace |
374 |
* @param element element to be stored at the specified position |
375 |
* @return the element previously at the specified position |
376 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
377 |
*/ |
378 |
public E set(int index, E element) { |
379 |
if (index >= size) |
380 |
throw new IndexOutOfBoundsException(ioobe(index)); |
381 |
|
382 |
E oldValue = (E) elementData[index]; |
383 |
elementData[index] = element; |
384 |
return oldValue; |
385 |
} |
386 |
|
387 |
/** |
388 |
* Appends the specified element to the end of this list. |
389 |
* |
390 |
* @param e element to be appended to this list |
391 |
* @return <tt>true</tt> (as specified by {@link Collection#add}) |
392 |
*/ |
393 |
public boolean add(E e) { |
394 |
modCount++; |
395 |
int s = size; |
396 |
if (s >= elementData.length) |
397 |
growArray(s + 1); |
398 |
elementData[s] = e; |
399 |
size = s + 1; |
400 |
return true; |
401 |
} |
402 |
|
403 |
/** |
404 |
* Inserts the specified element at the specified position in this |
405 |
* list. Shifts the element currently at that position (if any) and |
406 |
* any subsequent elements to the right (adds one to their indices). |
407 |
* |
408 |
* @param index index at which the specified element is to be inserted |
409 |
* @param element element to be inserted |
410 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
411 |
*/ |
412 |
public void add(int index, E element) { |
413 |
int s = size; |
414 |
if (index > s || index < 0) |
415 |
throw new IndexOutOfBoundsException(ioobe(index)); |
416 |
modCount++; |
417 |
if (s >= elementData.length) |
418 |
growArray(s + 1); |
419 |
System.arraycopy(elementData, index, |
420 |
elementData, index + 1, s - index); |
421 |
elementData[index] = element; |
422 |
size = s + 1; |
423 |
} |
424 |
|
425 |
/** |
426 |
* Removes the element at the specified position in this list. |
427 |
* Shifts any subsequent elements to the left (subtracts one from their |
428 |
* indices). |
429 |
* |
430 |
* @param index the index of the element to be removed |
431 |
* @return the element that was removed from the list |
432 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
433 |
*/ |
434 |
public E remove(int index) { |
435 |
int s = size - 1; |
436 |
if (index > s) |
437 |
throw new IndexOutOfBoundsException(ioobe(index)); |
438 |
modCount++; |
439 |
E oldValue = (E)elementData[index]; |
440 |
int numMoved = s - index; |
441 |
if (numMoved > 0) |
442 |
System.arraycopy(elementData, index + 1, |
443 |
elementData, index, numMoved); |
444 |
elementData[s] = null; |
445 |
size = s; |
446 |
return oldValue; |
447 |
} |
448 |
|
449 |
/** |
450 |
* Removes the first occurrence of the specified element from this list, |
451 |
* if it is present. If the list does not contain the element, it is |
452 |
* unchanged. More formally, removes the element with the lowest index |
453 |
* <tt>i</tt> such that |
454 |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt> |
455 |
* (if such an element exists). Returns <tt>true</tt> if this list |
456 |
* contained the specified element (or equivalently, if this list |
457 |
* changed as a result of the call). |
458 |
* |
459 |
* @param o element to be removed from this list, if present |
460 |
* @return <tt>true</tt> if this list contained the specified element |
461 |
*/ |
462 |
public boolean remove(Object o) { |
463 |
if (o == null) { |
464 |
for (int index = 0; index < size; index++) |
465 |
if (elementData[index] == null) { |
466 |
fastRemove(index); |
467 |
return true; |
468 |
} |
469 |
} else { |
470 |
for (int index = 0; index < size; index++) |
471 |
if (o.equals(elementData[index])) { |
472 |
fastRemove(index); |
473 |
return true; |
474 |
} |
475 |
} |
476 |
return false; |
477 |
} |
478 |
|
479 |
/* |
480 |
* Private remove method that skips bounds checking and does not |
481 |
* return the value removed. |
482 |
*/ |
483 |
private void fastRemove(int index) { |
484 |
modCount++; |
485 |
int numMoved = size - index - 1; |
486 |
if (numMoved > 0) |
487 |
System.arraycopy(elementData, index+1, elementData, index, |
488 |
numMoved); |
489 |
elementData[--size] = null; // Let gc do its work |
490 |
} |
491 |
|
492 |
/** |
493 |
* Removes all of the elements from this list. The list will |
494 |
* be empty after this call returns. |
495 |
*/ |
496 |
public void clear() { |
497 |
modCount++; |
498 |
|
499 |
// Let gc do its work |
500 |
for (int i = 0; i < size; i++) |
501 |
elementData[i] = null; |
502 |
|
503 |
size = 0; |
504 |
} |
505 |
|
506 |
/** |
507 |
* Appends all of the elements in the specified collection to the end of |
508 |
* this list, in the order that they are returned by the |
509 |
* specified collection's Iterator. The behavior of this operation is |
510 |
* undefined if the specified collection is modified while the operation |
511 |
* is in progress. (This implies that the behavior of this call is |
512 |
* undefined if the specified collection is this list, and this |
513 |
* list is nonempty.) |
514 |
* |
515 |
* @param c collection containing elements to be added to this list |
516 |
* @return <tt>true</tt> if this list changed as a result of the call |
517 |
* @throws NullPointerException if the specified collection is null |
518 |
*/ |
519 |
public boolean addAll(Collection<? extends E> c) { |
520 |
Object[] a = c.toArray(); |
521 |
int numNew = a.length; |
522 |
ensureCapacity(size + numNew); // Increments modCount |
523 |
System.arraycopy(a, 0, elementData, size, numNew); |
524 |
size += numNew; |
525 |
return numNew != 0; |
526 |
} |
527 |
|
528 |
/** |
529 |
* Inserts all of the elements in the specified collection into this |
530 |
* list, starting at the specified position. Shifts the element |
531 |
* currently at that position (if any) and any subsequent elements to |
532 |
* the right (increases their indices). The new elements will appear |
533 |
* in the list in the order that they are returned by the |
534 |
* specified collection's iterator. |
535 |
* |
536 |
* @param index index at which to insert the first element from the |
537 |
* specified collection |
538 |
* @param c collection containing elements to be added to this list |
539 |
* @return <tt>true</tt> if this list changed as a result of the call |
540 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
541 |
* @throws NullPointerException if the specified collection is null |
542 |
*/ |
543 |
public boolean addAll(int index, Collection<? extends E> c) { |
544 |
if (index > size || index < 0) |
545 |
throw new IndexOutOfBoundsException(ioobe(index)); |
546 |
|
547 |
Object[] a = c.toArray(); |
548 |
int numNew = a.length; |
549 |
ensureCapacity(size + numNew); // Increments modCount |
550 |
|
551 |
int numMoved = size - index; |
552 |
if (numMoved > 0) |
553 |
System.arraycopy(elementData, index, elementData, index + numNew, |
554 |
numMoved); |
555 |
|
556 |
System.arraycopy(a, 0, elementData, index, numNew); |
557 |
size += numNew; |
558 |
return numNew != 0; |
559 |
} |
560 |
|
561 |
/** |
562 |
* Removes from this list all of the elements whose index is between |
563 |
* <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive. |
564 |
* Shifts any succeeding elements to the left (reduces their index). |
565 |
* This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements. |
566 |
* (If <tt>toIndex==fromIndex</tt>, this operation has no effect.) |
567 |
* |
568 |
* @param fromIndex index of first element to be removed |
569 |
* @param toIndex index after last element to be removed |
570 |
* @throws IndexOutOfBoundsException if fromIndex or toIndex out of |
571 |
* range (fromIndex < 0 || fromIndex >= size() || toIndex |
572 |
* > size() || toIndex < fromIndex) |
573 |
*/ |
574 |
protected void removeRange(int fromIndex, int toIndex) { |
575 |
modCount++; |
576 |
int numMoved = size - toIndex; |
577 |
System.arraycopy(elementData, toIndex, elementData, fromIndex, |
578 |
numMoved); |
579 |
|
580 |
// Let gc do its work |
581 |
int newSize = size - (toIndex-fromIndex); |
582 |
while (size != newSize) |
583 |
elementData[--size] = null; |
584 |
} |
585 |
|
586 |
/** |
587 |
* Save the state of the <tt>ArrayList</tt> instance to a stream (that |
588 |
* is, serialize it). |
589 |
* |
590 |
* @serialData The length of the array backing the <tt>ArrayList</tt> |
591 |
* instance is emitted (int), followed by all of its elements |
592 |
* (each an <tt>Object</tt>) in the proper order. |
593 |
*/ |
594 |
private void writeObject(java.io.ObjectOutputStream s) |
595 |
throws java.io.IOException{ |
596 |
// Write out element count, and any hidden stuff |
597 |
int expectedModCount = modCount; |
598 |
s.defaultWriteObject(); |
599 |
|
600 |
// Write out array length |
601 |
s.writeInt(elementData.length); |
602 |
|
603 |
// Write out all elements in the proper order. |
604 |
for (int i=0; i<size; i++) |
605 |
s.writeObject(elementData[i]); |
606 |
|
607 |
if (expectedModCount != modCount) { |
608 |
throw new ConcurrentModificationException(); |
609 |
} |
610 |
|
611 |
} |
612 |
|
613 |
/** |
614 |
* Reconstitute the <tt>ArrayList</tt> instance from a stream (that is, |
615 |
* deserialize it). |
616 |
*/ |
617 |
private void readObject(java.io.ObjectInputStream s) |
618 |
throws java.io.IOException, ClassNotFoundException { |
619 |
// Read in size, and any hidden stuff |
620 |
s.defaultReadObject(); |
621 |
|
622 |
// Read in array length and allocate array |
623 |
int arrayLength = s.readInt(); |
624 |
Object[] a = elementData = new Object[arrayLength]; |
625 |
|
626 |
// Read in all elements in the proper order. |
627 |
for (int i=0; i<size; i++) |
628 |
a[i] = s.readObject(); |
629 |
} |
630 |
|
631 |
|
632 |
/** |
633 |
* Returns a list-iterator of the elements in this list (in proper |
634 |
* sequence), starting at the specified position in the list. |
635 |
* Obeys the general contract of <tt>List.listIterator(int)</tt>.<p> |
636 |
* |
637 |
* The list-iterator is <i>fail-fast</i>: if the list is structurally |
638 |
* modified at any time after the Iterator is created, in any way except |
639 |
* through the list-iterator's own <tt>remove</tt> or <tt>add</tt> |
640 |
* methods, the list-iterator will throw a |
641 |
* <tt>ConcurrentModificationException</tt>. Thus, in the face of |
642 |
* concurrent modification, the iterator fails quickly and cleanly, rather |
643 |
* than risking arbitrary, non-deterministic behavior at an undetermined |
644 |
* time in the future. |
645 |
* |
646 |
* @param index index of the first element to be returned from the |
647 |
* list-iterator (by a call to <tt>next</tt>) |
648 |
* @return a ListIterator of the elements in this list (in proper |
649 |
* sequence), starting at the specified position in the list |
650 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
651 |
* @see List#listIterator(int) |
652 |
*/ |
653 |
public ListIterator<E> listIterator(int index) { |
654 |
if (index < 0 || index > size) |
655 |
throw new IndexOutOfBoundsException(ioobe(index)); |
656 |
return new ArrayListIterator(index); |
657 |
} |
658 |
|
659 |
/** |
660 |
* {@inheritDoc} |
661 |
*/ |
662 |
public ListIterator<E> listIterator() { |
663 |
return new ArrayListIterator(0); |
664 |
} |
665 |
|
666 |
/** |
667 |
* Returns an iterator over the elements in this list in proper sequence. |
668 |
* |
669 |
* @return an iterator over the elements in this list in proper sequence |
670 |
*/ |
671 |
public Iterator<E> iterator() { |
672 |
return new ArrayListIterator(0); |
673 |
} |
674 |
|
675 |
/** |
676 |
* A streamlined version of AbstractList.ListItr |
677 |
*/ |
678 |
final class ArrayListIterator implements ListIterator<E> { |
679 |
int cursor; // index of next element to return; |
680 |
int lastRet; // index of last element, or -1 if no such |
681 |
int expectedModCount; // to check for CME |
682 |
|
683 |
ArrayListIterator(int index) { |
684 |
cursor = index; |
685 |
lastRet = -1; |
686 |
expectedModCount = modCount; |
687 |
} |
688 |
|
689 |
public boolean hasNext() { |
690 |
return cursor != size; |
691 |
} |
692 |
|
693 |
public boolean hasPrevious() { |
694 |
return cursor != 0; |
695 |
} |
696 |
|
697 |
public int nextIndex() { |
698 |
return cursor; |
699 |
} |
700 |
|
701 |
public int previousIndex() { |
702 |
return cursor - 1; |
703 |
} |
704 |
|
705 |
public E next() { |
706 |
try { |
707 |
int i = cursor; |
708 |
E next = get(i); |
709 |
lastRet = i; |
710 |
cursor = i + 1; |
711 |
return next; |
712 |
} catch (IndexOutOfBoundsException ex) { |
713 |
throw new NoSuchElementException(); |
714 |
} finally { |
715 |
if (expectedModCount != modCount) |
716 |
throw new ConcurrentModificationException(); |
717 |
} |
718 |
} |
719 |
|
720 |
public E previous() { |
721 |
try { |
722 |
int i = cursor - 1; |
723 |
E prev = get(i); |
724 |
lastRet = i; |
725 |
cursor = i; |
726 |
return prev; |
727 |
} catch (IndexOutOfBoundsException ex) { |
728 |
throw new NoSuchElementException(); |
729 |
} finally { |
730 |
if (expectedModCount != modCount) |
731 |
throw new ConcurrentModificationException(); |
732 |
} |
733 |
} |
734 |
|
735 |
public void remove() { |
736 |
if (lastRet < 0) |
737 |
throw new IllegalStateException(); |
738 |
if (expectedModCount != modCount) |
739 |
throw new ConcurrentModificationException(); |
740 |
ArrayList.this.remove(lastRet); |
741 |
if (lastRet < cursor) |
742 |
cursor--; |
743 |
lastRet = -1; |
744 |
expectedModCount = modCount; |
745 |
} |
746 |
|
747 |
public void set(E e) { |
748 |
if (lastRet < 0) |
749 |
throw new IllegalStateException(); |
750 |
if (expectedModCount != modCount) |
751 |
throw new ConcurrentModificationException(); |
752 |
ArrayList.this.set(lastRet, e); |
753 |
expectedModCount = modCount; |
754 |
} |
755 |
|
756 |
public void add(E e) { |
757 |
if (expectedModCount != modCount) |
758 |
throw new ConcurrentModificationException(); |
759 |
try { |
760 |
ArrayList.this.add(cursor++, e); |
761 |
lastRet = -1; |
762 |
expectedModCount = modCount; |
763 |
} catch (IndexOutOfBoundsException ex) { |
764 |
throw new ConcurrentModificationException(); |
765 |
} |
766 |
} |
767 |
} |
768 |
} |