--- jsr166/src/main/java/util/PriorityQueue.java 2003/06/23 02:26:15 1.6
+++ jsr166/src/main/java/util/PriorityQueue.java 2003/07/26 13:17:51 1.10
@@ -11,25 +11,28 @@
* elements are tied for least value, no guarantees are made as to
* which of these elements is returned.
*
- *
A priority queue has a capacity. The capacity is the size of
- * the array used internally to store the elements on the queue. It is always at least
- * as large as the queue size. As elements are added to a priority queue,
- * its capacity grows automatically. The details of the growth policy are not
- * specified.
+ *
A priority queue has a capacity. The capacity is the
+ * size of the array used internally to store the elements on the
+ * queue. It is always at least as large as the queue size. As
+ * elements are added to a priority queue, its capacity grows
+ * automatically. The details of the growth policy are not specified.
*
- *
Implementation note: this implementation provides O(log(n)) time for
- * the insertion methods (offer, poll, remove() and add)
- * methods; linear time for the remove(Object) and
- * contains(Object) methods; and constant time for the retrieval methods (peek,
- * element, and size).
+ *
Implementation note: this implementation provides O(log(n)) time
+ *for the insertion methods (offer, poll,
+ *remove() and add) methods; linear time for the
+ *remove(Object) and contains(Object) methods; and
+ *constant time for the retrieval methods (peek,
+ *element, and size).
*
*
This class is a member of the
*
* Java Collections Framework.
+ * @since 1.5
+ * @author Josh Bloch
*/
public class PriorityQueue extends AbstractQueue
- implements Queue
-{
+ implements Queue,
+ java.io.Serializable {
private static final int DEFAULT_INITIAL_CAPACITY = 11;
/**
@@ -65,8 +68,9 @@ public class PriorityQueue extends Ab
private transient int modCount = 0;
/**
- * Create a new priority queue with the default initial capacity (11)
- * that orders its elements according to their natural ordering (using Comparable.)
+ * Create a new priority queue with the default initial capacity
+ * (11) that orders its elements according to their natural
+ * ordering (using Comparable.)
*/
public PriorityQueue() {
this(DEFAULT_INITIAL_CAPACITY);
@@ -74,7 +78,8 @@ public class PriorityQueue extends Ab
/**
* Create a new priority queue with the specified initial capacity
- * that orders its elements according to their natural ordering (using Comparable.)
+ * that orders its elements according to their natural ordering
+ * (using Comparable.)
*
* @param initialCapacity the initial capacity for this priority queue.
*/
@@ -92,7 +97,7 @@ public class PriorityQueue extends Ab
public PriorityQueue(int initialCapacity, Comparator comparator) {
if (initialCapacity < 1)
initialCapacity = 1;
- queue = new E[initialCapacity + 1];
+ queue = (E[]) new Object[initialCapacity + 1];
this.comparator = comparator;
}
@@ -121,17 +126,14 @@ public class PriorityQueue extends Ab
Integer.MAX_VALUE - 1);
if (initialCapacity < 1)
initialCapacity = 1;
- queue = new E[initialCapacity + 1];
+ queue = (E[]) new Object[initialCapacity + 1];
- /* Commented out to compile with generics compiler
if (initialElements instanceof Sorted) {
comparator = ((Sorted)initialElements).comparator();
for (Iterator i = initialElements.iterator(); i.hasNext(); )
queue[++size] = i.next();
} else {
- */
- {
comparator = null;
for (Iterator i = initialElements.iterator(); i.hasNext(); )
add(i.next());
@@ -141,9 +143,10 @@ public class PriorityQueue extends Ab
// Queue Methods
/**
- * Remove and return the minimal element from this priority queue if
- * it contains one or more elements, otherwise return null. The term
- * minimal is defined according to this priority queue's order.
+ * Remove and return the minimal element from this priority queue
+ * if it contains one or more elements, otherwise return
+ * null. The term minimal is defined according to
+ * this priority queue's order.
*
* @return the minimal element from this priority queue if it contains
* one or more elements, otherwise null.
@@ -155,12 +158,13 @@ public class PriorityQueue extends Ab
}
/**
- * Return, but do not remove, the minimal element from the priority queue,
- * or return null if the queue is empty. The term minimal is
- * defined according to this priority queue's order. This method returns
- * the same object reference that would be returned by by the
- * poll method. The two methods differ in that this method
- * does not remove the element from the priority queue.
+ * Return, but do not remove, the minimal element from the
+ * priority queue, or return null if the queue is empty.
+ * The term minimal is defined according to this priority
+ * queue's order. This method returns the same object reference
+ * that would be returned by by the poll method. The two
+ * methods differ in that this method does not remove the element
+ * from the priority queue.
*
* @return the minimal element from this priority queue if it contains
* one or more elements, otherwise null.
@@ -177,11 +181,12 @@ public class PriorityQueue extends Ab
* specified element (or equivalently, if this collection changed as a
* result of the call).
*
- * @param element the element to be removed from this collection, if present.
+ * @param element the element to be removed from this collection,
+ * if present.
* @return true if this collection changed as a result of the
* call
* @throws ClassCastException if the specified element cannot be compared
- * with elements currently in the priority queue according
+ * with elements currently in the priority queue according
* to the priority queue's ordering.
* @throws NullPointerException if the specified element is null.
*/
@@ -212,50 +217,50 @@ public class PriorityQueue extends Ab
* elements of the priority queue will be returned by this iterator in the
* order specified by the queue, which is to say the order they would be
* returned by repeated calls to poll.
- *
+ *
* @return an Iterator over the elements in this priority queue.
*/
public Iterator iterator() {
- return new Itr();
+ return new Itr();
}
private class Itr implements Iterator {
- /**
- * Index (into queue array) of element to be returned by
+ /**
+ * Index (into queue array) of element to be returned by
* subsequent call to next.
- */
- int cursor = 1;
+ */
+ private int cursor = 1;
+
+ /**
+ * Index of element returned by most recent call to next or
+ * previous. Reset to 0 if this element is deleted by a call
+ * to remove.
+ */
+ private int lastRet = 0;
+
+ /**
+ * The modCount value that the iterator believes that the backing
+ * List should have. If this expectation is violated, the iterator
+ * has detected concurrent modification.
+ */
+ private int expectedModCount = modCount;
- /**
- * Index of element returned by most recent call to next or
- * previous. Reset to 0 if this element is deleted by a call
- * to remove.
- */
- int lastRet = 0;
-
- /**
- * The modCount value that the iterator believes that the backing
- * List should have. If this expectation is violated, the iterator
- * has detected concurrent modification.
- */
- int expectedModCount = modCount;
-
- public boolean hasNext() {
- return cursor <= size;
- }
+ public boolean hasNext() {
+ return cursor <= size;
+ }
- public E next() {
+ public E next() {
checkForComodification();
if (cursor > size)
- throw new NoSuchElementException();
+ throw new NoSuchElementException();
E result = queue[cursor];
lastRet = cursor++;
return result;
- }
+ }
- public void remove() {
- if (lastRet == 0)
- throw new IllegalStateException();
+ public void remove() {
+ if (lastRet == 0)
+ throw new IllegalStateException();
checkForComodification();
PriorityQueue.this.remove(lastRet);
@@ -263,17 +268,17 @@ public class PriorityQueue extends Ab
cursor--;
lastRet = 0;
expectedModCount = modCount;
- }
+ }
- final void checkForComodification() {
- if (modCount != expectedModCount)
- throw new ConcurrentModificationException();
- }
+ final void checkForComodification() {
+ if (modCount != expectedModCount)
+ throw new ConcurrentModificationException();
+ }
}
/**
* Returns the number of elements in this priority queue.
- *
+ *
* @return the number of elements in this priority queue.
*/
public int size() {
@@ -286,7 +291,7 @@ public class PriorityQueue extends Ab
* @param element the element to add.
* @return true
* @throws ClassCastException if the specified element cannot be compared
- * with elements currently in the priority queue according
+ * with elements currently in the priority queue according
* to the priority queue's ordering.
* @throws NullPointerException if the specified element is null.
*/
@@ -294,11 +299,12 @@ public class PriorityQueue extends Ab
if (element == null)
throw new NullPointerException();
modCount++;
+ ++size;
// Grow backing store if necessary
- if (++size == queue.length) {
- E[] newQueue = new E[2 * queue.length];
- System.arraycopy(queue, 0, newQueue, 0, size);
+ while (size >= queue.length) {
+ E[] newQueue = (E[]) new Object[2 * queue.length];
+ System.arraycopy(queue, 0, newQueue, 0, queue.length);
queue = newQueue;
}
@@ -405,9 +411,9 @@ public class PriorityQueue extends Ab
* null if it uses its elements' natural ordering.
*
* @return the comparator associated with this priority queue, or
- * null if it uses its elements' natural ordering.
+ * null if it uses its elements' natural ordering.
*/
- Comparator comparator() {
+ public Comparator comparator() {
return comparator;
}
@@ -418,35 +424,37 @@ public class PriorityQueue extends Ab
* @serialData The length of the array backing the instance is
* emitted (int), followed by all of its elements (each an
* Object) in the proper order.
+ * @param s the stream
*/
private synchronized void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException{
- // Write out element count, and any hidden stuff
- s.defaultWriteObject();
+ // Write out element count, and any hidden stuff
+ s.defaultWriteObject();
// Write out array length
s.writeInt(queue.length);
- // Write out all elements in the proper order.
- for (int i=0; iArrayList instance from a stream (that is,
* deserialize it).
+ * @param s the stream
*/
private synchronized void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
- // Read in size, and any hidden stuff
- s.defaultReadObject();
+ // Read in size, and any hidden stuff
+ s.defaultReadObject();
// Read in array length and allocate array
int arrayLength = s.readInt();
- queue = new E[arrayLength];
+ queue = (E[]) new Object[arrayLength];
- // Read in all elements in the proper order.
- for (int i=0; i