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1 : tim 1.2 package java.util;
2 : tim 1.1
3 :     /**
4 : dholmes 1.23 * An unbounded priority {@linkplain Queue queue} based on a priority heap.
5 :     * This queue orders
6 : brian 1.6 * elements according to an order specified at construction time, which is
7 : tim 1.19 * specified in the same manner as {@link java.util.TreeSet} and
8 : dholmes 1.18 * {@link java.util.TreeMap}: elements are ordered
9 : tim 1.2 * either according to their <i>natural order</i> (see {@link Comparable}), or
10 : tim 1.19 * according to a {@link java.util.Comparator}, depending on which
11 : dholmes 1.18 * constructor is used.
12 : tim 1.19 * <p>The <em>head</em> of this queue is the <em>least</em> element with
13 :     * respect to the specified ordering.
14 : dholmes 1.18 * If multiple elements are tied for least value, the
15 : tim 1.14 * head is one of those elements. A priority queue does not permit
16 : dholmes 1.11 * <tt>null</tt> elements.
17 : tim 1.14 *
18 : dholmes 1.11 * <p>The {@link #remove()} and {@link #poll()} methods remove and
19 :     * return the head of the queue.
20 :     *
21 :     * <p>The {@link #element()} and {@link #peek()} methods return, but do
22 :     * not delete, the head of the queue.
23 : tim 1.2 *
24 : dl 1.7 * <p>A priority queue has a <i>capacity</i>. The capacity is the
25 :     * size of the array used internally to store the elements on the
26 : dholmes 1.20 * queue.
27 : dholmes 1.18 * It is always at least as large as the queue size. As
28 : dl 1.7 * elements are added to a priority queue, its capacity grows
29 :     * automatically. The details of the growth policy are not specified.
30 : tim 1.2 *
31 : dl 1.29 * <p>The Iterator provided in method {@link #iterator()} is <em>not</em>
32 :     * guaranteed to traverse the elements of the PriorityQueue in any
33 :     * particular order. If you need ordered traversal, consider using
34 :     * <tt>Arrays.sort(pq.toArray())</tt>.
35 :     *
36 :     * <p> <strong>Note that this implementation is not synchronized.</strong>
37 :     * Multiple threads should not access a <tt>PriorityQueue</tt>
38 :     * instance concurrently if any of the threads modifies the list
39 :     * structurally. Instead, use the thread-safe {@link
40 :     * java.util.concurrent.BlockingPriorityQueue} class.
41 :     *
42 :     *
43 : dholmes 1.11 * <p>Implementation note: this implementation provides O(log(n)) time
44 :     * for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
45 :     * <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
46 :     * <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and
47 :     * constant time for the retrieval methods (<tt>peek</tt>,
48 :     * <tt>element</tt>, and <tt>size</tt>).
49 : tim 1.2 *
50 :     * <p>This class is a member of the
51 :     * <a href="{@docRoot}/../guide/collections/index.html">
52 :     * Java Collections Framework</a>.
53 : dl 1.7 * @since 1.5
54 :     * @author Josh Bloch
55 : tim 1.2 */
56 :     public class PriorityQueue<E> extends AbstractQueue<E>
57 : dl 1.22 implements Queue<E>, java.io.Serializable {
58 : dholmes 1.11
59 : tim 1.2 private static final int DEFAULT_INITIAL_CAPACITY = 11;
60 : tim 1.1
61 : tim 1.2 /**
62 :     * Priority queue represented as a balanced binary heap: the two children
63 :     * of queue[n] are queue[2*n] and queue[2*n + 1]. The priority queue is
64 :     * ordered by comparator, or by the elements' natural ordering, if
65 : brian 1.6 * comparator is null: For each node n in the heap and each descendant d
66 :     * of n, n <= d.
67 : tim 1.2 *
68 : brian 1.6 * The element with the lowest value is in queue[1], assuming the queue is
69 :     * nonempty. (A one-based array is used in preference to the traditional
70 :     * zero-based array to simplify parent and child calculations.)
71 : tim 1.2 *
72 :     * queue.length must be >= 2, even if size == 0.
73 :     */
74 : tim 1.16 private transient Object[] queue;
75 : tim 1.1
76 : tim 1.2 /**
77 :     * The number of elements in the priority queue.
78 :     */
79 :     private int size = 0;
80 : tim 1.1
81 : tim 1.2 /**
82 :     * The comparator, or null if priority queue uses elements'
83 :     * natural ordering.
84 :     */
85 : tim 1.16 private final Comparator<? super E> comparator;
86 : tim 1.2
87 :     /**
88 :     * The number of times this priority queue has been
89 :     * <i>structurally modified</i>. See AbstractList for gory details.
90 :     */
91 : dl 1.5 private transient int modCount = 0;
92 : tim 1.2
93 :     /**
94 : dholmes 1.21 * Creates a <tt>PriorityQueue</tt> with the default initial capacity
95 : dl 1.7 * (11) that orders its elements according to their natural
96 : tim 1.24 * ordering (using <tt>Comparable</tt>).
97 : tim 1.2 */
98 :     public PriorityQueue() {
99 : dholmes 1.11 this(DEFAULT_INITIAL_CAPACITY, null);
100 : tim 1.1 }
101 : tim 1.2
102 :     /**
103 : dholmes 1.21 * Creates a <tt>PriorityQueue</tt> with the specified initial capacity
104 : dl 1.7 * that orders its elements according to their natural ordering
105 : tim 1.24 * (using <tt>Comparable</tt>).
106 : tim 1.2 *
107 :     * @param initialCapacity the initial capacity for this priority queue.
108 : dholmes 1.23 * @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
109 :     * than 1
110 : tim 1.2 */
111 :     public PriorityQueue(int initialCapacity) {
112 :     this(initialCapacity, null);
113 : tim 1.1 }
114 : tim 1.2
115 :     /**
116 : dholmes 1.21 * Creates a <tt>PriorityQueue</tt> with the specified initial capacity
117 : tim 1.2 * that orders its elements according to the specified comparator.
118 :     *
119 :     * @param initialCapacity the initial capacity for this priority queue.
120 :     * @param comparator the comparator used to order this priority queue.
121 : dholmes 1.11 * If <tt>null</tt> then the order depends on the elements' natural
122 :     * ordering.
123 : dholmes 1.15 * @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
124 :     * than 1
125 : tim 1.2 */
126 : dholmes 1.23 public PriorityQueue(int initialCapacity,
127 :     Comparator<? super E> comparator) {
128 : tim 1.2 if (initialCapacity < 1)
129 : dholmes 1.15 throw new IllegalArgumentException();
130 : tim 1.16 this.queue = new Object[initialCapacity + 1];
131 : tim 1.2 this.comparator = comparator;
132 : tim 1.1 }
133 :    
134 : tim 1.2 /**
135 : dl 1.22 * Common code to initialize underlying queue array across
136 :     * constructors below.
137 :     */
138 :     private void initializeArray(Collection<? extends E> c) {
139 :     int sz = c.size();
140 :     int initialCapacity = (int)Math.min((sz * 110L) / 100,
141 :     Integer.MAX_VALUE - 1);
142 :     if (initialCapacity < 1)
143 :     initialCapacity = 1;
144 :    
145 :     this.queue = new Object[initialCapacity + 1];
146 :     }
147 :    
148 :     /**
149 :     * Initially fill elements of the queue array under the
150 :     * knowledge that it is sorted or is another PQ, in which
151 :     * case we can just place the elements without fixups.
152 :     */
153 :     private void fillFromSorted(Collection<? extends E> c) {
154 :     for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
155 :     queue[++size] = i.next();
156 :     }
157 :    
158 :    
159 :     /**
160 :     * Initially fill elements of the queue array that is
161 :     * not to our knowledge sorted, so we must add them
162 :     * one by one.
163 :     */
164 :     private void fillFromUnsorted(Collection<? extends E> c) {
165 :     for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
166 :     add(i.next());
167 :     }
168 :    
169 :     /**
170 :     * Creates a <tt>PriorityQueue</tt> containing the elements in the
171 :     * specified collection. The priority queue has an initial
172 :     * capacity of 110% of the size of the specified collection or 1
173 :     * if the collection is empty. If the specified collection is an
174 : tim 1.25 * instance of a {@link java.util.SortedSet} or is another
175 : dl 1.22 * <tt>PriorityQueue</tt>, the priority queue will be sorted
176 :     * according to the same comparator, or according to its elements'
177 :     * natural order if the collection is sorted according to its
178 :     * elements' natural order. Otherwise, the priority queue is
179 :     * ordered according to its elements' natural order.
180 : tim 1.2 *
181 : dholmes 1.15 * @param c the collection whose elements are to be placed
182 : tim 1.2 * into this priority queue.
183 :     * @throws ClassCastException if elements of the specified collection
184 :     * cannot be compared to one another according to the priority
185 :     * queue's ordering.
186 : dholmes 1.15 * @throws NullPointerException if <tt>c</tt> or any element within it
187 :     * is <tt>null</tt>
188 : tim 1.2 */
189 : tim 1.16 public PriorityQueue(Collection<? extends E> c) {
190 : dl 1.22 initializeArray(c);
191 : dl 1.27 if (c instanceof SortedSet) {
192 : dl 1.28 // @fixme double-cast workaround for compiler
193 :     SortedSet<? extends E> s = (SortedSet<? extends E>) (SortedSet)c;
194 : dl 1.22 comparator = (Comparator<? super E>)s.comparator();
195 :     fillFromSorted(s);
196 : dl 1.27 } else if (c instanceof PriorityQueue) {
197 : dl 1.22 PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c;
198 :     comparator = (Comparator<? super E>)s.comparator();
199 :     fillFromSorted(s);
200 : tim 1.26 } else {
201 : tim 1.2 comparator = null;
202 : dl 1.22 fillFromUnsorted(c);
203 : tim 1.2 }
204 : dl 1.22 }
205 :    
206 :     /**
207 :     * Creates a <tt>PriorityQueue</tt> containing the elements in the
208 :     * specified collection. The priority queue has an initial
209 :     * capacity of 110% of the size of the specified collection or 1
210 :     * if the collection is empty. This priority queue will be sorted
211 :     * according to the same comparator as the given collection, or
212 :     * according to its elements' natural order if the collection is
213 :     * sorted according to its elements' natural order.
214 :     *
215 :     * @param c the collection whose elements are to be placed
216 :     * into this priority queue.
217 :     * @throws ClassCastException if elements of the specified collection
218 :     * cannot be compared to one another according to the priority
219 :     * queue's ordering.
220 :     * @throws NullPointerException if <tt>c</tt> or any element within it
221 :     * is <tt>null</tt>
222 :     */
223 :     public PriorityQueue(PriorityQueue<? extends E> c) {
224 :     initializeArray(c);
225 :     comparator = (Comparator<? super E>)c.comparator();
226 :     fillFromSorted(c);
227 :     }
228 : dholmes 1.18
229 : dl 1.22 /**
230 :     * Creates a <tt>PriorityQueue</tt> containing the elements in the
231 :     * specified collection. The priority queue has an initial
232 :     * capacity of 110% of the size of the specified collection or 1
233 :     * if the collection is empty. This priority queue will be sorted
234 :     * according to the same comparator as the given collection, or
235 :     * according to its elements' natural order if the collection is
236 :     * sorted according to its elements' natural order.
237 :     *
238 :     * @param c the collection whose elements are to be placed
239 :     * into this priority queue.
240 :     * @throws ClassCastException if elements of the specified collection
241 :     * cannot be compared to one another according to the priority
242 :     * queue's ordering.
243 :     * @throws NullPointerException if <tt>c</tt> or any element within it
244 :     * is <tt>null</tt>
245 :     */
246 :     public PriorityQueue(SortedSet<? extends E> c) {
247 :     initializeArray(c);
248 :     comparator = (Comparator<? super E>)c.comparator();
249 :     fillFromSorted(c);
250 : tim 1.1 }
251 :    
252 : dl 1.22 /**
253 :     * Resize array, if necessary, to be able to hold given index
254 :     */
255 :     private void grow(int index) {
256 :     int newlen = queue.length;
257 :     if (index < newlen) // don't need to grow
258 :     return;
259 :     if (index == Integer.MAX_VALUE)
260 :     throw new OutOfMemoryError();
261 :     while (newlen <= index) {
262 :     if (newlen >= Integer.MAX_VALUE / 2) // avoid overflow
263 :     newlen = Integer.MAX_VALUE;
264 :     else
265 :     newlen <<= 2;
266 :     }
267 :     Object[] newQueue = new Object[newlen];
268 :     System.arraycopy(queue, 0, newQueue, 0, queue.length);
269 :     queue = newQueue;
270 :     }
271 :    
272 : tim 1.2 // Queue Methods
273 :    
274 : dholmes 1.23
275 :    
276 : tim 1.2 /**
277 : dholmes 1.11 * Add the specified element to this priority queue.
278 : tim 1.2 *
279 : dholmes 1.11 * @return <tt>true</tt>
280 :     * @throws ClassCastException if the specified element cannot be compared
281 :     * with elements currently in the priority queue according
282 :     * to the priority queue's ordering.
283 : dholmes 1.18 * @throws NullPointerException if the specified element is <tt>null</tt>.
284 : tim 1.2 */
285 : dholmes 1.18 public boolean offer(E o) {
286 :     if (o == null)
287 : dholmes 1.11 throw new NullPointerException();
288 :     modCount++;
289 :     ++size;
290 :    
291 :     // Grow backing store if necessary
292 : dl 1.22 if (size >= queue.length)
293 :     grow(size);
294 : dholmes 1.11
295 : dholmes 1.18 queue[size] = o;
296 : dholmes 1.11 fixUp(size);
297 :     return true;
298 :     }
299 :    
300 : tim 1.1 public E poll() {
301 : tim 1.2 if (size == 0)
302 :     return null;
303 : tim 1.16 return (E) remove(1);
304 : tim 1.1 }
305 : tim 1.2
306 : tim 1.1 public E peek() {
307 : tim 1.16 return (E) queue[1];
308 : tim 1.1 }
309 :    
310 : dholmes 1.23 // Collection Methods - the first two override to update docs
311 : dholmes 1.11
312 :     /**
313 : dholmes 1.23 * Adds the specified element to this queue.
314 :     * @return <tt>true</tt> (as per the general contract of
315 :     * <tt>Collection.add</tt>).
316 :     *
317 :     * @throws NullPointerException {@inheritDoc}
318 : dholmes 1.15 * @throws ClassCastException if the specified element cannot be compared
319 :     * with elements currently in the priority queue according
320 :     * to the priority queue's ordering.
321 : dholmes 1.11 */
322 : dholmes 1.18 public boolean add(E o) {
323 :     return super.add(o);
324 : dholmes 1.11 }
325 :    
326 : dholmes 1.23
327 : tim 1.14 /**
328 : dholmes 1.23 * Adds all of the elements in the specified collection to this queue.
329 :     * The behavior of this operation is undefined if
330 :     * the specified collection is modified while the operation is in
331 :     * progress. (This implies that the behavior of this call is undefined if
332 :     * the specified collection is this queue, and this queue is nonempty.)
333 :     * <p>
334 :     * This implementation iterates over the specified collection, and adds
335 :     * each object returned by the iterator to this collection, in turn.
336 :     * @throws NullPointerException {@inheritDoc}
337 : dholmes 1.15 * @throws ClassCastException if any element cannot be compared
338 :     * with elements currently in the priority queue according
339 :     * to the priority queue's ordering.
340 : tim 1.14 */
341 :     public boolean addAll(Collection<? extends E> c) {
342 :     return super.addAll(c);
343 :     }
344 : dholmes 1.11
345 : dholmes 1.23
346 :     /**
347 :     * Removes a single instance of the specified element from this
348 :     * queue, if it is present. More formally,
349 :     * removes an element <tt>e</tt> such that <tt>(o==null ? e==null :
350 :     * o.equals(e))</tt>, if the queue contains one or more such
351 :     * elements. Returns <tt>true</tt> if the queue contained the
352 :     * specified element (or equivalently, if the queue changed as a
353 :     * result of the call).
354 :     *
355 :     * <p>This implementation iterates over the queue looking for the
356 :     * specified element. If it finds the element, it removes the element
357 :     * from the queue using the iterator's remove method.<p>
358 :     *
359 :     */
360 : dl 1.12 public boolean remove(Object o) {
361 : dholmes 1.11 if (o == null)
362 : dholmes 1.15 return false;
363 : tim 1.2
364 :     if (comparator == null) {
365 :     for (int i = 1; i <= size; i++) {
366 : tim 1.16 if (((Comparable<E>)queue[i]).compareTo((E)o) == 0) {
367 : tim 1.2 remove(i);
368 :     return true;
369 :     }
370 :     }
371 :     } else {
372 :     for (int i = 1; i <= size; i++) {
373 : tim 1.16 if (comparator.compare((E)queue[i], (E)o) == 0) {
374 : tim 1.2 remove(i);
375 :     return true;
376 :     }
377 :     }
378 :     }
379 : tim 1.1 return false;
380 :     }
381 : tim 1.2
382 : dholmes 1.23 /**
383 :     * Returns an iterator over the elements in this queue. The iterator
384 :     * does not return the elements in any particular order.
385 :     *
386 :     * @return an iterator over the elements in this queue.
387 :     */
388 : tim 1.2 public Iterator<E> iterator() {
389 : dl 1.7 return new Itr();
390 : tim 1.2 }
391 :    
392 :     private class Itr implements Iterator<E> {
393 : dl 1.7 /**
394 :     * Index (into queue array) of element to be returned by
395 : tim 1.2 * subsequent call to next.
396 : dl 1.7 */
397 :     private int cursor = 1;
398 : tim 1.2
399 : dl 1.7 /**
400 :     * Index of element returned by most recent call to next or
401 :     * previous. Reset to 0 if this element is deleted by a call
402 :     * to remove.
403 :     */
404 :     private int lastRet = 0;
405 :    
406 :     /**
407 :     * The modCount value that the iterator believes that the backing
408 :     * List should have. If this expectation is violated, the iterator
409 :     * has detected concurrent modification.
410 :     */
411 :     private int expectedModCount = modCount;
412 : tim 1.2
413 : dl 1.7 public boolean hasNext() {
414 :     return cursor <= size;
415 :     }
416 :    
417 :     public E next() {
418 : tim 1.2 checkForComodification();
419 :     if (cursor > size)
420 : dl 1.7 throw new NoSuchElementException();
421 : tim 1.16 E result = (E) queue[cursor];
422 : tim 1.2 lastRet = cursor++;
423 :     return result;
424 : dl 1.7 }
425 : tim 1.2
426 : dl 1.7 public void remove() {
427 :     if (lastRet == 0)
428 :     throw new IllegalStateException();
429 : tim 1.2 checkForComodification();
430 :    
431 :     PriorityQueue.this.remove(lastRet);
432 :     if (lastRet < cursor)
433 :     cursor--;
434 :     lastRet = 0;
435 :     expectedModCount = modCount;
436 : dl 1.7 }
437 : tim 1.2
438 : dl 1.7 final void checkForComodification() {
439 :     if (modCount != expectedModCount)
440 :     throw new ConcurrentModificationException();
441 :     }
442 : tim 1.2 }
443 :    
444 : tim 1.1 public int size() {
445 : tim 1.2 return size;
446 : tim 1.1 }
447 : tim 1.2
448 :     /**
449 :     * Remove all elements from the priority queue.
450 :     */
451 :     public void clear() {
452 :     modCount++;
453 :    
454 :     // Null out element references to prevent memory leak
455 :     for (int i=1; i<=size; i++)
456 :     queue[i] = null;
457 :    
458 :     size = 0;
459 :     }
460 :    
461 :     /**
462 :     * Removes and returns the ith element from queue. Recall
463 :     * that queue is one-based, so 1 <= i <= size.
464 :     *
465 :     * XXX: Could further special-case i==size, but is it worth it?
466 :     * XXX: Could special-case i==0, but is it worth it?
467 :     */
468 :     private E remove(int i) {
469 :     assert i <= size;
470 :     modCount++;
471 :    
472 : tim 1.16 E result = (E) queue[i];
473 : tim 1.2 queue[i] = queue[size];
474 :     queue[size--] = null; // Drop extra ref to prevent memory leak
475 :     if (i <= size)
476 :     fixDown(i);
477 :     return result;
478 : tim 1.1 }
479 :    
480 : tim 1.2 /**
481 :     * Establishes the heap invariant (described above) assuming the heap
482 :     * satisfies the invariant except possibly for the leaf-node indexed by k
483 :     * (which may have a nextExecutionTime less than its parent's).
484 :     *
485 :     * This method functions by "promoting" queue[k] up the hierarchy
486 :     * (by swapping it with its parent) repeatedly until queue[k]
487 :     * is greater than or equal to its parent.
488 :     */
489 :     private void fixUp(int k) {
490 :     if (comparator == null) {
491 :     while (k > 1) {
492 :     int j = k >> 1;
493 : tim 1.16 if (((Comparable<E>)queue[j]).compareTo((E)queue[k]) <= 0)
494 : tim 1.2 break;
495 : tim 1.16 Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
496 : tim 1.2 k = j;
497 :     }
498 :     } else {
499 :     while (k > 1) {
500 :     int j = k >> 1;
501 : tim 1.16 if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
502 : tim 1.2 break;
503 : tim 1.16 Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
504 : tim 1.2 k = j;
505 :     }
506 :     }
507 :     }
508 :    
509 :     /**
510 :     * Establishes the heap invariant (described above) in the subtree
511 :     * rooted at k, which is assumed to satisfy the heap invariant except
512 :     * possibly for node k itself (which may be greater than its children).
513 :     *
514 :     * This method functions by "demoting" queue[k] down the hierarchy
515 :     * (by swapping it with its smaller child) repeatedly until queue[k]
516 :     * is less than or equal to its children.
517 :     */
518 :     private void fixDown(int k) {
519 :     int j;
520 :     if (comparator == null) {
521 :     while ((j = k << 1) <= size) {
522 : tim 1.16 if (j<size && ((Comparable<E>)queue[j]).compareTo((E)queue[j+1]) > 0)
523 : tim 1.2 j++; // j indexes smallest kid
524 : tim 1.16 if (((Comparable<E>)queue[k]).compareTo((E)queue[j]) <= 0)
525 : tim 1.2 break;
526 : tim 1.16 Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
527 : tim 1.2 k = j;
528 :     }
529 :     } else {
530 :     while ((j = k << 1) <= size) {
531 : tim 1.16 if (j < size && comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
532 : tim 1.2 j++; // j indexes smallest kid
533 : tim 1.16 if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
534 : tim 1.2 break;
535 : tim 1.16 Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
536 : tim 1.2 k = j;
537 :     }
538 :     }
539 :     }
540 :    
541 : dholmes 1.23
542 :     /**
543 :     * Returns the comparator used to order this collection, or <tt>null</tt>
544 :     * if this collection is sorted according to its elements natural ordering
545 : tim 1.24 * (using <tt>Comparable</tt>).
546 : dholmes 1.23 *
547 :     * @return the comparator used to order this collection, or <tt>null</tt>
548 :     * if this collection is sorted according to its elements natural ordering.
549 :     */
550 : tim 1.16 public Comparator<? super E> comparator() {
551 : tim 1.2 return comparator;
552 :     }
553 : dl 1.5
554 :     /**
555 :     * Save the state of the instance to a stream (that
556 :     * is, serialize it).
557 :     *
558 :     * @serialData The length of the array backing the instance is
559 :     * emitted (int), followed by all of its elements (each an
560 :     * <tt>Object</tt>) in the proper order.
561 : dl 1.7 * @param s the stream
562 : dl 1.5 */
563 : dl 1.22 private void writeObject(java.io.ObjectOutputStream s)
564 : dl 1.5 throws java.io.IOException{
565 : dl 1.7 // Write out element count, and any hidden stuff
566 :     s.defaultWriteObject();
567 : dl 1.5
568 :     // Write out array length
569 :     s.writeInt(queue.length);
570 :    
571 : dl 1.7 // Write out all elements in the proper order.
572 :     for (int i=0; i<size; i++)
573 : dl 1.5 s.writeObject(queue[i]);
574 :     }
575 :    
576 :     /**
577 :     * Reconstitute the <tt>ArrayList</tt> instance from a stream (that is,
578 :     * deserialize it).
579 : dl 1.7 * @param s the stream
580 : dl 1.5 */
581 : dl 1.22 private void readObject(java.io.ObjectInputStream s)
582 : dl 1.5 throws java.io.IOException, ClassNotFoundException {
583 : dl 1.7 // Read in size, and any hidden stuff
584 :     s.defaultReadObject();
585 : dl 1.5
586 :     // Read in array length and allocate array
587 :     int arrayLength = s.readInt();
588 : tim 1.16 queue = new Object[arrayLength];
589 : dl 1.5
590 : dl 1.7 // Read in all elements in the proper order.
591 :     for (int i=0; i<size; i++)
592 : tim 1.16 queue[i] = s.readObject();
593 : dl 1.5 }
594 :    
595 : tim 1.1 }
596 : dholmes 1.11

Doug Lea
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