--- jsr166/src/main/java/util/PriorityQueue.java 2003/07/28 10:08:24 1.13
+++ jsr166/src/main/java/util/PriorityQueue.java 2003/08/05 06:18:17 1.20
@@ -3,15 +3,17 @@
/**
* An unbounded priority 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 TreeSet} and {@link TreeMap}:
- * elements are ordered
+ * specified in the same manner as {@link java.util.TreeSet} and
+ * {@link java.util.TreeMap}: elements are ordered
* either according to their natural order (see {@link Comparable}), or
- * according to a {@link Comparator}, depending on which constructor is used.
- * The head of this queue is the least element with respect to the
- * specified ordering. If multiple elements are tied for least value, the
- * head is one of those elements. A priority queue does not permit
+ * according to a {@link java.util.Comparator}, depending on which
+ * constructor is used.
+ *
The head of this queue is the least element with
+ * respect to the specified ordering.
+ * If multiple elements are tied for least value, the
+ * head is one of those elements. A priority queue does not permit
* null elements.
- *
+ *
*
The {@link #remove()} and {@link #poll()} methods remove and
* return the head of the queue.
*
@@ -20,7 +22,8 @@
*
*
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
+ * 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.
*
@@ -38,7 +41,7 @@
* @author Josh Bloch
*/
public class PriorityQueue extends AbstractQueue
- implements Queue, java.io.Serializable {
+ implements Sorted, Queue, java.io.Serializable {
private static final int DEFAULT_INITIAL_CAPACITY = 11;
@@ -55,7 +58,7 @@ public class PriorityQueue extends Ab
*
* queue.length must be >= 2, even if size == 0.
*/
- private transient E[] queue;
+ private transient Object[] queue;
/**
* The number of elements in the priority queue.
@@ -66,7 +69,7 @@ public class PriorityQueue extends Ab
* The comparator, or null if priority queue uses elements'
* natural ordering.
*/
- private final Comparator comparator;
+ private final Comparator super E> comparator;
/**
* The number of times this priority queue has been
@@ -102,18 +105,21 @@ public class PriorityQueue extends Ab
* @param comparator the comparator used to order this priority queue.
* If null then the order depends on the elements' natural
* ordering.
+ * @throws IllegalArgumentException if initialCapacity is less
+ * than 1
*/
- public PriorityQueue(int initialCapacity, Comparator comparator) {
+ public PriorityQueue(int initialCapacity, Comparator super E> comparator) {
if (initialCapacity < 1)
- initialCapacity = 1;
- queue = (E[]) new Object[initialCapacity + 1];
+ throw new IllegalArgumentException();
+ this.queue = new Object[initialCapacity + 1];
this.comparator = comparator;
}
/**
* Create a PriorityQueue containing the elements in the specified
* collection. The priority queue has an initial capacity of 110% of the
- * size of the specified collection. If the specified collection
+ * size of the specified collection or 1 if the collection is empty.
+ * If the specified collection
* implements the {@link Sorted} interface, 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 elements'
@@ -121,31 +127,31 @@ public class PriorityQueue extends Ab
* Sorted, the priority queue is ordered according to
* its elements' natural order.
*
- * @param initialElements the collection whose elements are to be placed
+ * @param c the collection whose elements are to be placed
* into this priority queue.
* @throws ClassCastException if elements of the specified collection
* cannot be compared to one another according to the priority
* queue's ordering.
- * @throws NullPointerException if the specified collection or an
- * element of the specified collection is null.
+ * @throws NullPointerException if c or any element within it
+ * is null
*/
- public PriorityQueue(Collection initialElements) {
- int sz = initialElements.size();
+ public PriorityQueue(Collection extends E> c) {
+ int sz = c.size();
int initialCapacity = (int)Math.min((sz * 110L) / 100,
Integer.MAX_VALUE - 1);
if (initialCapacity < 1)
initialCapacity = 1;
- queue = (E[]) new Object[initialCapacity + 1];
- if (initialElements instanceof Sorted) {
- comparator = ((Sorted)initialElements).comparator();
- for (Iterator i = initialElements.iterator(); i.hasNext(); )
- queue[++size] = i.next();
+ this.queue = new Object[initialCapacity + 1];
+
+ if (c instanceof Sorted) {
+ comparator = (Comparator super E>)((Sorted)c).comparator();
} else {
comparator = null;
- for (Iterator i = initialElements.iterator(); i.hasNext(); )
- add(i.next());
}
+
+ for (Iterator extends E> i = c.iterator(); i.hasNext(); )
+ add(i.next());
}
// Queue Methods
@@ -153,27 +159,26 @@ public class PriorityQueue extends Ab
/**
* Add the specified element to this priority queue.
*
- * @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
* to the priority queue's ordering.
- * @throws NullPointerException if the specified element is null.
+ * @throws NullPointerException if the specified element is null.
*/
- public boolean offer(E element) {
- if (element == null)
+ public boolean offer(E o) {
+ if (o == null)
throw new NullPointerException();
modCount++;
++size;
// Grow backing store if necessary
while (size >= queue.length) {
- E[] newQueue = (E[]) new Object[2 * queue.length];
+ Object[] newQueue = new Object[2 * queue.length];
System.arraycopy(queue, 0, newQueue, 0, queue.length);
queue = newQueue;
}
- queue[size] = element;
+ queue[size] = o;
fixUp(size);
return true;
}
@@ -181,11 +186,11 @@ public class PriorityQueue extends Ab
public E poll() {
if (size == 0)
return null;
- return remove(1);
+ return (E) remove(1);
}
public E peek() {
- return queue[1];
+ return (E) queue[1];
}
// Collection Methods
@@ -194,35 +199,39 @@ public class PriorityQueue extends Ab
/**
* @throws NullPointerException if the specified element is null.
+ * @throws ClassCastException if the specified element cannot be compared
+ * with elements currently in the priority queue according
+ * to the priority queue's ordering.
*/
- public boolean add(E element) {
- return super.add(element);
+ public boolean add(E o) {
+ return super.add(o);
}
- // /**
- // * @throws NullPointerException if any element is null.
- // */
- // public boolean addAll(Collection c) {
- // return super.addAll(c);
- // }
-
/**
- * @throws NullPointerException if the specified element is null.
+ * @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 c or any element in c
+ * is null
*/
+ public boolean addAll(Collection extends E> c) {
+ return super.addAll(c);
+ }
+
public boolean remove(Object o) {
if (o == null)
- throw new NullPointerException();
+ return false;
if (comparator == null) {
for (int i = 1; i <= size; i++) {
- if (((Comparable)queue[i]).compareTo(o) == 0) {
+ if (((Comparable)queue[i]).compareTo((E)o) == 0) {
remove(i);
return true;
}
}
} else {
for (int i = 1; i <= size; i++) {
- if (comparator.compare(queue[i], (E)o) == 0) {
+ if (comparator.compare((E)queue[i], (E)o) == 0) {
remove(i);
return true;
}
@@ -231,14 +240,6 @@ public class PriorityQueue extends Ab
return false;
}
- /**
- * Returns an iterator over the elements in this priority queue. The
- * 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();
}
@@ -272,7 +273,7 @@ public class PriorityQueue extends Ab
checkForComodification();
if (cursor > size)
throw new NoSuchElementException();
- E result = queue[cursor];
+ E result = (E) queue[cursor];
lastRet = cursor++;
return result;
}
@@ -328,7 +329,7 @@ public class PriorityQueue extends Ab
assert i <= size;
modCount++;
- E result = queue[i];
+ E result = (E) queue[i];
queue[i] = queue[size];
queue[size--] = null; // Drop extra ref to prevent memory leak
if (i <= size)
@@ -349,17 +350,17 @@ public class PriorityQueue extends Ab
if (comparator == null) {
while (k > 1) {
int j = k >> 1;
- if (((Comparable)queue[j]).compareTo(queue[k]) <= 0)
+ if (((Comparable)queue[j]).compareTo((E)queue[k]) <= 0)
break;
- E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
+ Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
k = j;
}
} else {
while (k > 1) {
int j = k >> 1;
- if (comparator.compare(queue[j], queue[k]) <= 0)
+ if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
break;
- E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
+ Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
k = j;
}
}
@@ -378,26 +379,26 @@ public class PriorityQueue extends Ab
int j;
if (comparator == null) {
while ((j = k << 1) <= size) {
- if (j 0)
+ if (j)queue[j]).compareTo((E)queue[j+1]) > 0)
j++; // j indexes smallest kid
- if (((Comparable)queue[k]).compareTo(queue[j]) <= 0)
+ if (((Comparable)queue[k]).compareTo((E)queue[j]) <= 0)
break;
- E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
+ Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
k = j;
}
} else {
while ((j = k << 1) <= size) {
- if (j < size && comparator.compare(queue[j], queue[j+1]) > 0)
+ if (j < size && comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
j++; // j indexes smallest kid
- if (comparator.compare(queue[k], queue[j]) <= 0)
+ if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
break;
- E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
+ Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp;
k = j;
}
}
}
- public Comparator comparator() {
+ public Comparator super E> comparator() {
return comparator;
}
@@ -435,11 +436,11 @@ public class PriorityQueue extends Ab
// Read in array length and allocate array
int arrayLength = s.readInt();
- queue = (E[]) new Object[arrayLength];
+ queue = new Object[arrayLength];
// Read in all elements in the proper order.
for (int i=0; i