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package java.util; |
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/* |
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* Todo |
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* |
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* 1) Make it serializable. |
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*/ |
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/** |
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* An unbounded priority queue based on a priority heap. This queue orders |
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* elements according to the order specified at creation time. This order is |
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* |
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* queue.length must be >= 2, even if size == 0. |
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*/ |
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private E[] queue; |
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private transient E[] queue; |
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/** |
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* The number of elements in the priority queue. |
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* The number of times this priority queue has been |
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* <i>structurally modified</i>. See AbstractList for gory details. |
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*/ |
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private int modCount = 0; |
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private transient int modCount = 0; |
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/** |
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* Create a new priority queue with the default initial capacity (11) |
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initialCapacity = 1; |
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queue = new E[initialCapacity + 1]; |
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/* Commented out to compile with generics compiler |
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if (initialElements instanceof Sorted) { |
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comparator = ((Sorted)initialElements).comparator(); |
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for (Iterator<E> i = initialElements.iterator(); i.hasNext(); ) |
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queue[++size] = i.next(); |
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} else { |
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*/ |
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{ |
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comparator = null; |
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for (Iterator<E> i = initialElements.iterator(); i.hasNext(); ) |
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add(i.next()); |
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* or <tt>null</tt> if the queue is empty. The term <i>minimal</i> is |
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* defined according to this priority queue's order. This method returns |
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* the same object reference that would be returned by by the |
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* <tt>poll</tt> method. The two methods differ in that this method |
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* <tt>poll</tt> method. The two methods differ in that this method |
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* does not remove the element from the priority queue. |
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* |
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* @return the minimal element from this priority queue if it contains |
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* @return <tt>true</tt> if this collection changed as a result of the |
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* call |
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* @throws ClassCastException if the specified element cannot be compared |
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* with elements currently in the priority queue according |
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* with elements currently in the priority queue according |
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* to the priority queue's ordering. |
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* @throws NullPointerException if the specified element is null. |
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*/ |
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/** |
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* Returns an iterator over the elements in this priority queue. The |
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* first element returned by this iterator is the same element that |
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* first element returned by this iterator is the same element that |
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* would be returned by a call to <tt>peek</tt>. |
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* |
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* |
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* @return an <tt>Iterator</tt> over the elements in this priority queue. |
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*/ |
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public Iterator<E> iterator() { |
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return new Itr(); |
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return new Itr(); |
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} |
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private class Itr implements Iterator<E> { |
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/** |
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* Index (into queue array) of element to be returned by |
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/** |
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* Index (into queue array) of element to be returned by |
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* subsequent call to next. |
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*/ |
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int cursor = 1; |
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/** |
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* Index of element returned by most recent call to next or |
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* previous. Reset to 0 if this element is deleted by a call |
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* to remove. |
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*/ |
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int lastRet = 0; |
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/** |
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* The modCount value that the iterator believes that the backing |
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* List should have. If this expectation is violated, the iterator |
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* has detected concurrent modification. |
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*/ |
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int expectedModCount = modCount; |
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*/ |
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int cursor = 1; |
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public boolean hasNext() { |
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return cursor <= size; |
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} |
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/** |
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* Index of element returned by most recent call to next or |
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* previous. Reset to 0 if this element is deleted by a call |
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* to remove. |
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*/ |
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int lastRet = 0; |
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/** |
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* The modCount value that the iterator believes that the backing |
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* List should have. If this expectation is violated, the iterator |
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* has detected concurrent modification. |
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*/ |
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int expectedModCount = modCount; |
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public boolean hasNext() { |
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return cursor <= size; |
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} |
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public E next() { |
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public E next() { |
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checkForComodification(); |
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if (cursor > size) |
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throw new NoSuchElementException(); |
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throw new NoSuchElementException(); |
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E result = queue[cursor]; |
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lastRet = cursor++; |
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return result; |
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} |
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} |
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public void remove() { |
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if (lastRet == 0) |
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throw new IllegalStateException(); |
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public void remove() { |
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if (lastRet == 0) |
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throw new IllegalStateException(); |
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checkForComodification(); |
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PriorityQueue.this.remove(lastRet); |
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cursor--; |
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lastRet = 0; |
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expectedModCount = modCount; |
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} |
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} |
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final void checkForComodification() { |
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if (modCount != expectedModCount) |
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throw new ConcurrentModificationException(); |
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} |
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final void checkForComodification() { |
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if (modCount != expectedModCount) |
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throw new ConcurrentModificationException(); |
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} |
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} |
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/** |
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* Returns the number of elements in this priority queue. |
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* |
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* |
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* @return the number of elements in this priority queue. |
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*/ |
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public int size() { |
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* @param element the element to add. |
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* @return true |
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* @throws ClassCastException if the specified element cannot be compared |
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* with elements currently in the priority queue according |
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* with elements currently in the priority queue according |
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* to the priority queue's ordering. |
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* @throws NullPointerException if the specified element is null. |
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*/ |
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* <tt>null</tt> if it uses its elements' natural ordering. |
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* |
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* @return the comparator associated with this priority queue, or |
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* <tt>null</tt> if it uses its elements' natural ordering. |
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* <tt>null</tt> if it uses its elements' natural ordering. |
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*/ |
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Comparator<E> comparator() { |
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Comparator comparator() { |
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return comparator; |
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} |
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/** |
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* Save the state of the instance to a stream (that |
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* is, serialize it). |
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* |
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* @serialData The length of the array backing the instance is |
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* emitted (int), followed by all of its elements (each an |
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* <tt>Object</tt>) in the proper order. |
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*/ |
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private synchronized void writeObject(java.io.ObjectOutputStream s) |
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throws java.io.IOException{ |
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// Write out element count, and any hidden stuff |
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s.defaultWriteObject(); |
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|
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// Write out array length |
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s.writeInt(queue.length); |
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|
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// Write out all elements in the proper order. |
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for (int i=0; i<size; i++) |
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s.writeObject(queue[i]); |
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} |
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|
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/** |
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* Reconstitute the <tt>ArrayList</tt> instance from a stream (that is, |
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* deserialize it). |
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*/ |
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private synchronized void readObject(java.io.ObjectInputStream s) |
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throws java.io.IOException, ClassNotFoundException { |
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// Read in size, and any hidden stuff |
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s.defaultReadObject(); |
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// Read in array length and allocate array |
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int arrayLength = s.readInt(); |
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queue = new E[arrayLength]; |
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// Read in all elements in the proper order. |
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for (int i=0; i<size; i++) |
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queue[i] = (E)s.readObject(); |
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} |
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} |