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

Doug Lea
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