--- jsr166/src/main/java/util/PriorityQueue.java	2003/08/05 12:11:08	1.22
+++ jsr166/src/main/java/util/PriorityQueue.java	2003/08/25 23:50:24	1.33
@@ -1,7 +1,8 @@
  package java.util;
 
 /**
- * An unbounded priority queue based on a priority heap.  This queue orders
+ * An unbounded priority {@linkplain Queue queue} based on a priority heap.  
+ * This queue orders
  * elements according to an order specified at construction time, which is
  * specified in the same manner as {@link java.util.TreeSet} and
  * {@link java.util.TreeMap}: elements are ordered
@@ -27,6 +28,18 @@
  * elements are added to a priority queue, its capacity grows
  * automatically.  The details of the growth policy are not specified.
  *
+ * <p>The Iterator provided in method {@link #iterator()} is <em>not</em>
+ * guaranteed to traverse the elements of the PriorityQueue in any
+ * particular order. If you need ordered traversal, consider using
+ * <tt>Arrays.sort(pq.toArray())</tt>.
+ *
+ * <p> <strong>Note that this implementation is not synchronized.</strong>
+ * Multiple threads should not access a <tt>PriorityQueue</tt>
+ * instance concurrently if any of the threads modifies the list
+ * structurally. Instead, use the thread-safe {@link
+ * java.util.concurrent.BlockingPriorityQueue} class.
+ *
+ * 
  * <p>Implementation note: this implementation provides O(log(n)) time
  * for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
  * <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
@@ -43,6 +56,8 @@
 public class PriorityQueue<E> extends AbstractQueue<E>
     implements Queue<E>, java.io.Serializable {
 
+    private static final long serialVersionUID = -7720805057305804111L;
+
     private static final int DEFAULT_INITIAL_CAPACITY = 11;
 
     /**
@@ -80,7 +95,7 @@ public class PriorityQueue<E> extends Ab
     /**
      * Creates a <tt>PriorityQueue</tt> with the default initial capacity
      * (11) that orders its elements according to their natural
-     * ordering (using <tt>Comparable</tt>.)
+     * ordering (using <tt>Comparable</tt>).
      */
     public PriorityQueue() {
         this(DEFAULT_INITIAL_CAPACITY, null);
@@ -89,9 +104,11 @@ public class PriorityQueue<E> extends Ab
     /**
      * Creates a <tt>PriorityQueue</tt> with the specified initial capacity
      * that orders its elements according to their natural ordering
-     * (using <tt>Comparable</tt>.)
+     * (using <tt>Comparable</tt>).
      *
      * @param initialCapacity the initial capacity for this priority queue.
+     * @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
+     * than 1
      */
     public PriorityQueue(int initialCapacity) {
         this(initialCapacity, null);
@@ -108,7 +125,8 @@ public class PriorityQueue<E> extends Ab
      * @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
      * than 1
      */
-    public PriorityQueue(int initialCapacity, Comparator<? super E> comparator) {
+    public PriorityQueue(int initialCapacity, 
+                         Comparator<? super E> comparator) {
         if (initialCapacity < 1)
             throw new IllegalArgumentException();
         this.queue = new Object[initialCapacity + 1];
@@ -155,7 +173,7 @@ public class PriorityQueue<E> extends Ab
      * specified collection.  The priority queue has an initial
      * capacity of 110% of the size of the specified collection or 1
      * if the collection is empty.  If the specified collection is an
-     * instance of a {@link SortedSet} or is another
+     * instance of a {@link java.util.SortedSet} or is another
      * <tt>PriorityQueue</tt>, the priority queue will be sorted
      * according to the same comparator, or according to its elements'
      * natural order if the collection is sorted according to its
@@ -172,17 +190,16 @@ public class PriorityQueue<E> extends Ab
      */
     public PriorityQueue(Collection<? extends E> c) {
         initializeArray(c);
-        if (c instanceof SortedSet<? extends E>) {
-            SortedSet<? extends E> s = (SortedSet<? extends E>) c;
+        if (c instanceof SortedSet) {
+            // @fixme double-cast workaround for compiler
+            SortedSet<? extends E> s = (SortedSet<? extends E>) (SortedSet)c;
             comparator = (Comparator<? super E>)s.comparator();
             fillFromSorted(s);
-        }
-        else if (c instanceof PriorityQueue<? extends E>) {
+        } else if (c instanceof PriorityQueue) {
             PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c;
             comparator = (Comparator<? super E>)s.comparator();
             fillFromSorted(s);
-        }
-        else {
+        } else {
             comparator = null;
             fillFromUnsorted(c);
         }
@@ -256,6 +273,8 @@ public class PriorityQueue<E> extends Ab
             
     // Queue Methods
 
+
+
     /**
      * Add the specified element to this priority queue.
      *
@@ -290,12 +309,14 @@ public class PriorityQueue<E> extends Ab
         return (E) queue[1];
     }
 
-    // Collection Methods
-
-    // these first two override just to get the throws docs
+    // Collection Methods - the first two override to update docs
 
     /**
-     * @throws NullPointerException if the specified element is <tt>null</tt>.
+     * Adds the specified element to this queue.
+     * @return <tt>true</tt> (as per the general contract of
+     * <tt>Collection.add</tt>).
+     *
+     * @throws NullPointerException {@inheritDoc}
      * @throws ClassCastException if the specified element cannot be compared
      * with elements currently in the priority queue according
      * to the priority queue's ordering.
@@ -304,17 +325,40 @@ public class PriorityQueue<E> extends Ab
         return super.add(o);
     }
 
+   
     /**
+     * Adds all of the elements in the specified collection to this queue.
+     * The behavior of this operation is undefined if
+     * the specified collection is modified while the operation is in
+     * progress.  (This implies that the behavior of this call is undefined if
+     * the specified collection is this queue, and this queue is nonempty.)
+     * <p>
+     * This implementation iterates over the specified collection, and adds
+     * each object returned by the iterator to this collection, in turn.
+     * @throws NullPointerException {@inheritDoc}
      * @throws ClassCastException if any element cannot be compared
      * with elements currently in the priority queue according
      * to the priority queue's ordering.
-     * @throws NullPointerException if <tt>c</tt> or any element in <tt>c</tt>
-     * is <tt>null</tt>
      */
     public boolean addAll(Collection<? extends E> c) {
         return super.addAll(c);
     }
 
+
+ /**
+     * Removes a single instance of the specified element from this
+     * queue, if it is present.  More formally,
+     * removes an element <tt>e</tt> such that <tt>(o==null ? e==null :
+     * o.equals(e))</tt>, if the queue contains one or more such
+     * elements.  Returns <tt>true</tt> if the queue contained the
+     * specified element (or equivalently, if the queue changed as a
+     * result of the call).
+     *
+     * <p>This implementation iterates over the queue looking for the
+     * specified element.  If it finds the element, it removes the element
+     * from the queue using the iterator's remove method.<p>
+     *
+     */
     public boolean remove(Object o) {
         if (o == null)
             return false;
@@ -337,6 +381,12 @@ public class PriorityQueue<E> extends Ab
         return false;
     }
 
+    /**
+     * Returns an iterator over the elements in this queue. The iterator
+     * does not return the elements in any particular order.
+     *
+     * @return an iterator over the elements in this queue.
+     */
     public Iterator<E> iterator() {
         return new Itr();
     }
@@ -381,8 +431,7 @@ public class PriorityQueue<E> extends Ab
             checkForComodification();
 
             PriorityQueue.this.remove(lastRet);
-            if (lastRet < cursor)
-                cursor--;
+            cursor--;
             lastRet = 0;
             expectedModCount = modCount;
         }
@@ -393,11 +442,6 @@ public class PriorityQueue<E> extends Ab
         }
     }
 
-    /**
-     * Returns the number of elements in this priority queue.
-     *
-     * @return the number of elements in this priority queue.
-     */
     public int size() {
         return size;
     }
@@ -419,8 +463,6 @@ public class PriorityQueue<E> extends Ab
      * Removes and returns the ith element from queue.  Recall
      * that queue is one-based, so 1 <= i <= size.
      *
-     * XXX: Could further special-case i==size, but is it worth it?
-     * XXX: Could special-case i==0, but is it worth it?
      */
     private E remove(int i) {
         assert i <= size;
@@ -475,7 +517,7 @@ public class PriorityQueue<E> extends Ab
     private void fixDown(int k) {
         int j;
         if (comparator == null) {
-            while ((j = k << 1) <= size) {
+            while ((j = k << 1) <= size && (j > 0)) {
                 if (j<size && ((Comparable<E>)queue[j]).compareTo((E)queue[j+1]) > 0)
                     j++; // j indexes smallest kid
                 if (((Comparable<E>)queue[k]).compareTo((E)queue[j]) <= 0)
@@ -484,7 +526,7 @@ public class PriorityQueue<E> extends Ab
                 k = j;
             }
         } else {
-            while ((j = k << 1) <= size) {
+            while ((j = k << 1) <= size && (j > 0)) {
                 if (j < size && comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
                     j++; // j indexes smallest kid
                 if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
@@ -495,6 +537,15 @@ public class PriorityQueue<E> extends Ab
         }
     }
 
+
+    /**
+     * Returns the comparator used to order this collection, or <tt>null</tt>
+     * if this collection is sorted according to its elements natural ordering
+     * (using <tt>Comparable</tt>).
+     *
+     * @return the comparator used to order this collection, or <tt>null</tt>
+     * if this collection is sorted according to its elements natural ordering.
+     */
     public Comparator<? super E> comparator() {
         return comparator;
     }