| 2 |
|
|
| 3 |
|
/** |
| 4 |
|
* An unbounded priority queue based on a priority heap. This queue orders |
| 5 |
< |
* elements according to the order specified at creation time. This order is |
| 6 |
< |
* specified as for {@link TreeSet} and {@link TreeMap}: Elements are ordered |
| 5 |
> |
* elements according to an order specified at construction time, which is |
| 6 |
> |
* specified in the same manner as {@link java.util.TreeSet} and |
| 7 |
> |
* {@link java.util.TreeMap}: elements are ordered |
| 8 |
|
* either according to their <i>natural order</i> (see {@link Comparable}), or |
| 9 |
< |
* according to a {@link Comparator}, depending on which constructor is used. |
| 10 |
< |
* The {@link #peek}, {@link #poll}, and {@link #remove} methods return the |
| 11 |
< |
* minimal element with respect to the specified ordering. If multiple |
| 12 |
< |
* these elements are tied for least value, no guarantees are made as to |
| 13 |
< |
* which of elements is returned. |
| 9 |
> |
* according to a {@link java.util.Comparator}, depending on which |
| 10 |
> |
* constructor is used. |
| 11 |
> |
* <p>The <em>head</em> of this queue is the <em>least</em> element with |
| 12 |
> |
* respect to the specified ordering. |
| 13 |
> |
* If multiple elements are tied for least value, the |
| 14 |
> |
* head is one of those elements. A priority queue does not permit |
| 15 |
> |
* <tt>null</tt> elements. |
| 16 |
|
* |
| 17 |
< |
* <p>Each priority queue has a <i>capacity</i>. The capacity is the size of |
| 18 |
< |
* the array used to store the elements on the queue. It is always at least |
| 16 |
< |
* as large as the queue size. As elements are added to a priority list, |
| 17 |
< |
* its capacity grows automatically. The details of the growth policy are not |
| 18 |
< |
* specified. |
| 17 |
> |
* <p>The {@link #remove()} and {@link #poll()} methods remove and |
| 18 |
> |
* return the head of the queue. |
| 19 |
|
* |
| 20 |
< |
*<p>Implementation note: this implementation provides O(log(n)) time for |
| 21 |
< |
* the <tt>offer</tt>, <tt>poll</tt>, <tt>remove()</tt> and <tt>add</tt> |
| 22 |
< |
* methods; linear time for the <tt>remove(Object)</tt> and |
| 23 |
< |
* <tt>contains</tt> methods; and constant time for the <tt>peek</tt>, |
| 24 |
< |
* <tt>element</tt>, and <tt>size</tt> methods. |
| 20 |
> |
* <p>The {@link #element()} and {@link #peek()} methods return, but do |
| 21 |
> |
* not delete, the head of the queue. |
| 22 |
> |
* |
| 23 |
> |
* <p>A priority queue has a <i>capacity</i>. The capacity is the |
| 24 |
> |
* size of the array used internally to store the elements on the |
| 25 |
> |
* queue. |
| 26 |
> |
* It is always at least as large as the queue size. As |
| 27 |
> |
* elements are added to a priority queue, its capacity grows |
| 28 |
> |
* automatically. The details of the growth policy are not specified. |
| 29 |
> |
* |
| 30 |
> |
* <p>Implementation note: this implementation provides O(log(n)) time |
| 31 |
> |
* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>, |
| 32 |
> |
* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the |
| 33 |
> |
* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and |
| 34 |
> |
* constant time for the retrieval methods (<tt>peek</tt>, |
| 35 |
> |
* <tt>element</tt>, and <tt>size</tt>). |
| 36 |
|
* |
| 37 |
|
* <p>This class is a member of the |
| 38 |
|
* <a href="{@docRoot}/../guide/collections/index.html"> |
| 39 |
|
* Java Collections Framework</a>. |
| 40 |
+ |
* @since 1.5 |
| 41 |
+ |
* @author Josh Bloch |
| 42 |
|
*/ |
| 43 |
|
public class PriorityQueue<E> extends AbstractQueue<E> |
| 44 |
< |
implements Queue<E> |
| 45 |
< |
{ |
| 44 |
> |
implements Queue<E>, java.io.Serializable { |
| 45 |
> |
|
| 46 |
|
private static final int DEFAULT_INITIAL_CAPACITY = 11; |
| 47 |
|
|
| 48 |
|
/** |
| 49 |
|
* Priority queue represented as a balanced binary heap: the two children |
| 50 |
|
* of queue[n] are queue[2*n] and queue[2*n + 1]. The priority queue is |
| 51 |
|
* ordered by comparator, or by the elements' natural ordering, if |
| 52 |
< |
* comparator is null: For each node n in the heap, and each descendant |
| 53 |
< |
* of n, d, n <= d. |
| 52 |
> |
* comparator is null: For each node n in the heap and each descendant d |
| 53 |
> |
* of n, n <= d. |
| 54 |
|
* |
| 55 |
< |
* The element with the lowest value is in queue[1] (assuming the queue is |
| 56 |
< |
* nonempty). A one-based array is used in preference to the traditional |
| 57 |
< |
* zero-based array to simplify parent and child calculations. |
| 55 |
> |
* The element with the lowest value is in queue[1], assuming the queue is |
| 56 |
> |
* nonempty. (A one-based array is used in preference to the traditional |
| 57 |
> |
* zero-based array to simplify parent and child calculations.) |
| 58 |
|
* |
| 59 |
|
* queue.length must be >= 2, even if size == 0. |
| 60 |
|
*/ |
| 61 |
< |
private transient E[] queue; |
| 61 |
> |
private transient Object[] queue; |
| 62 |
|
|
| 63 |
|
/** |
| 64 |
|
* The number of elements in the priority queue. |
| 69 |
|
* The comparator, or null if priority queue uses elements' |
| 70 |
|
* natural ordering. |
| 71 |
|
*/ |
| 72 |
< |
private final Comparator<E> comparator; |
| 72 |
> |
private final Comparator<? super E> comparator; |
| 73 |
|
|
| 74 |
|
/** |
| 75 |
|
* The number of times this priority queue has been |
| 78 |
|
private transient int modCount = 0; |
| 79 |
|
|
| 80 |
|
/** |
| 81 |
< |
* Create a new priority queue with the default initial capacity (11) |
| 82 |
< |
* that orders its elements according to their natural ordering. |
| 81 |
> |
* Creates a <tt>PriorityQueue</tt> with the default initial capacity |
| 82 |
> |
* (11) that orders its elements according to their natural |
| 83 |
> |
* ordering (using <tt>Comparable</tt>.) |
| 84 |
|
*/ |
| 85 |
|
public PriorityQueue() { |
| 86 |
< |
this(DEFAULT_INITIAL_CAPACITY); |
| 86 |
> |
this(DEFAULT_INITIAL_CAPACITY, null); |
| 87 |
|
} |
| 88 |
|
|
| 89 |
|
/** |
| 90 |
< |
* Create a new priority queue with the specified initial capacity |
| 91 |
< |
* that orders its elements according to their natural ordering. |
| 90 |
> |
* Creates a <tt>PriorityQueue</tt> with the specified initial capacity |
| 91 |
> |
* that orders its elements according to their natural ordering |
| 92 |
> |
* (using <tt>Comparable</tt>.) |
| 93 |
|
* |
| 94 |
|
* @param initialCapacity the initial capacity for this priority queue. |
| 95 |
|
*/ |
| 98 |
|
} |
| 99 |
|
|
| 100 |
|
/** |
| 101 |
< |
* Create a new priority queue with the specified initial capacity (11) |
| 101 |
> |
* Creates a <tt>PriorityQueue</tt> with the specified initial capacity |
| 102 |
|
* that orders its elements according to the specified comparator. |
| 103 |
|
* |
| 104 |
|
* @param initialCapacity the initial capacity for this priority queue. |
| 105 |
|
* @param comparator the comparator used to order this priority queue. |
| 106 |
+ |
* If <tt>null</tt> then the order depends on the elements' natural |
| 107 |
+ |
* ordering. |
| 108 |
+ |
* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less |
| 109 |
+ |
* than 1 |
| 110 |
|
*/ |
| 111 |
< |
public PriorityQueue(int initialCapacity, Comparator<E> comparator) { |
| 111 |
> |
public PriorityQueue(int initialCapacity, Comparator<? super E> comparator) { |
| 112 |
|
if (initialCapacity < 1) |
| 113 |
< |
initialCapacity = 1; |
| 114 |
< |
queue = new E[initialCapacity + 1]; |
| 113 |
> |
throw new IllegalArgumentException(); |
| 114 |
> |
this.queue = new Object[initialCapacity + 1]; |
| 115 |
|
this.comparator = comparator; |
| 116 |
|
} |
| 117 |
|
|
| 118 |
|
/** |
| 119 |
< |
* Create a new priority queue containing the elements in the specified |
| 120 |
< |
* collection. The priority queue has an initial capacity of 110% of the |
| 102 |
< |
* size of the specified collection. If the specified collection |
| 103 |
< |
* implements the {@link Sorted} interface, the priority queue will be |
| 104 |
< |
* sorted according to the same comparator, or according to its elements' |
| 105 |
< |
* natural order if the collection is sorted according to its elements' |
| 106 |
< |
* natural order. If the specified collection does not implement the |
| 107 |
< |
* <tt>Sorted</tt> interface, the priority queue is ordered according to |
| 108 |
< |
* its elements' natural order. |
| 109 |
< |
* |
| 110 |
< |
* @param initialElements the collection whose elements are to be placed |
| 111 |
< |
* into this priority queue. |
| 112 |
< |
* @throws ClassCastException if elements of the specified collection |
| 113 |
< |
* cannot be compared to one another according to the priority |
| 114 |
< |
* queue's ordering. |
| 115 |
< |
* @throws NullPointerException if the specified collection or an |
| 116 |
< |
* element of the specified collection is <tt>null</tt>. |
| 119 |
> |
* Common code to initialize underlying queue array across |
| 120 |
> |
* constructors below. |
| 121 |
|
*/ |
| 122 |
< |
public PriorityQueue(Collection<E> initialElements) { |
| 123 |
< |
int sz = initialElements.size(); |
| 122 |
> |
private void initializeArray(Collection<? extends E> c) { |
| 123 |
> |
int sz = c.size(); |
| 124 |
|
int initialCapacity = (int)Math.min((sz * 110L) / 100, |
| 125 |
|
Integer.MAX_VALUE - 1); |
| 126 |
|
if (initialCapacity < 1) |
| 127 |
|
initialCapacity = 1; |
| 124 |
– |
queue = new E[initialCapacity + 1]; |
| 128 |
|
|
| 129 |
< |
/* Commented out to compile with generics compiler |
| 129 |
> |
this.queue = new Object[initialCapacity + 1]; |
| 130 |
> |
} |
| 131 |
|
|
| 132 |
< |
if (initialElements instanceof Sorted) { |
| 133 |
< |
comparator = ((Sorted)initialElements).comparator(); |
| 134 |
< |
for (Iterator<E> i = initialElements.iterator(); i.hasNext(); ) |
| 135 |
< |
queue[++size] = i.next(); |
| 136 |
< |
} else { |
| 137 |
< |
*/ |
| 138 |
< |
{ |
| 132 |
> |
/** |
| 133 |
> |
* Initially fill elements of the queue array under the |
| 134 |
> |
* knowledge that it is sorted or is another PQ, in which |
| 135 |
> |
* case we can just place the elements without fixups. |
| 136 |
> |
*/ |
| 137 |
> |
private void fillFromSorted(Collection<? extends E> c) { |
| 138 |
> |
for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) |
| 139 |
> |
queue[++size] = i.next(); |
| 140 |
> |
} |
| 141 |
> |
|
| 142 |
> |
|
| 143 |
> |
/** |
| 144 |
> |
* Initially fill elements of the queue array that is |
| 145 |
> |
* not to our knowledge sorted, so we must add them |
| 146 |
> |
* one by one. |
| 147 |
> |
*/ |
| 148 |
> |
private void fillFromUnsorted(Collection<? extends E> c) { |
| 149 |
> |
for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) |
| 150 |
> |
add(i.next()); |
| 151 |
> |
} |
| 152 |
> |
|
| 153 |
> |
/** |
| 154 |
> |
* Creates a <tt>PriorityQueue</tt> containing the elements in the |
| 155 |
> |
* specified collection. The priority queue has an initial |
| 156 |
> |
* capacity of 110% of the size of the specified collection or 1 |
| 157 |
> |
* if the collection is empty. If the specified collection is an |
| 158 |
> |
* instance of a {@link SortedSet} or is another |
| 159 |
> |
* <tt>PriorityQueue</tt>, the priority queue will be sorted |
| 160 |
> |
* according to the same comparator, or according to its elements' |
| 161 |
> |
* natural order if the collection is sorted according to its |
| 162 |
> |
* elements' natural order. Otherwise, the priority queue is |
| 163 |
> |
* ordered according to its elements' natural order. |
| 164 |
> |
* |
| 165 |
> |
* @param c the collection whose elements are to be placed |
| 166 |
> |
* into this priority queue. |
| 167 |
> |
* @throws ClassCastException if elements of the specified collection |
| 168 |
> |
* cannot be compared to one another according to the priority |
| 169 |
> |
* queue's ordering. |
| 170 |
> |
* @throws NullPointerException if <tt>c</tt> or any element within it |
| 171 |
> |
* is <tt>null</tt> |
| 172 |
> |
*/ |
| 173 |
> |
public PriorityQueue(Collection<? extends E> c) { |
| 174 |
> |
initializeArray(c); |
| 175 |
> |
if (c instanceof SortedSet<? extends E>) { |
| 176 |
> |
SortedSet<? extends E> s = (SortedSet<? extends E>) c; |
| 177 |
> |
comparator = (Comparator<? super E>)s.comparator(); |
| 178 |
> |
fillFromSorted(s); |
| 179 |
> |
} |
| 180 |
> |
else if (c instanceof PriorityQueue<? extends E>) { |
| 181 |
> |
PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c; |
| 182 |
> |
comparator = (Comparator<? super E>)s.comparator(); |
| 183 |
> |
fillFromSorted(s); |
| 184 |
> |
} |
| 185 |
> |
else { |
| 186 |
|
comparator = null; |
| 187 |
< |
for (Iterator<E> i = initialElements.iterator(); i.hasNext(); ) |
| 137 |
< |
add(i.next()); |
| 187 |
> |
fillFromUnsorted(c); |
| 188 |
|
} |
| 189 |
|
} |
| 190 |
|
|
| 191 |
+ |
/** |
| 192 |
+ |
* Creates a <tt>PriorityQueue</tt> containing the elements in the |
| 193 |
+ |
* specified collection. The priority queue has an initial |
| 194 |
+ |
* capacity of 110% of the size of the specified collection or 1 |
| 195 |
+ |
* if the collection is empty. This priority queue will be sorted |
| 196 |
+ |
* according to the same comparator as the given collection, or |
| 197 |
+ |
* according to its elements' natural order if the collection is |
| 198 |
+ |
* sorted according to its elements' natural order. |
| 199 |
+ |
* |
| 200 |
+ |
* @param c the collection whose elements are to be placed |
| 201 |
+ |
* into this priority queue. |
| 202 |
+ |
* @throws ClassCastException if elements of the specified collection |
| 203 |
+ |
* cannot be compared to one another according to the priority |
| 204 |
+ |
* queue's ordering. |
| 205 |
+ |
* @throws NullPointerException if <tt>c</tt> or any element within it |
| 206 |
+ |
* is <tt>null</tt> |
| 207 |
+ |
*/ |
| 208 |
+ |
public PriorityQueue(PriorityQueue<? extends E> c) { |
| 209 |
+ |
initializeArray(c); |
| 210 |
+ |
comparator = (Comparator<? super E>)c.comparator(); |
| 211 |
+ |
fillFromSorted(c); |
| 212 |
+ |
} |
| 213 |
+ |
|
| 214 |
+ |
/** |
| 215 |
+ |
* Creates a <tt>PriorityQueue</tt> containing the elements in the |
| 216 |
+ |
* specified collection. The priority queue has an initial |
| 217 |
+ |
* capacity of 110% of the size of the specified collection or 1 |
| 218 |
+ |
* if the collection is empty. This priority queue will be sorted |
| 219 |
+ |
* according to the same comparator as the given collection, or |
| 220 |
+ |
* according to its elements' natural order if the collection is |
| 221 |
+ |
* sorted according to its elements' natural order. |
| 222 |
+ |
* |
| 223 |
+ |
* @param c the collection whose elements are to be placed |
| 224 |
+ |
* into this priority queue. |
| 225 |
+ |
* @throws ClassCastException if elements of the specified collection |
| 226 |
+ |
* cannot be compared to one another according to the priority |
| 227 |
+ |
* queue's ordering. |
| 228 |
+ |
* @throws NullPointerException if <tt>c</tt> or any element within it |
| 229 |
+ |
* is <tt>null</tt> |
| 230 |
+ |
*/ |
| 231 |
+ |
public PriorityQueue(SortedSet<? extends E> c) { |
| 232 |
+ |
initializeArray(c); |
| 233 |
+ |
comparator = (Comparator<? super E>)c.comparator(); |
| 234 |
+ |
fillFromSorted(c); |
| 235 |
+ |
} |
| 236 |
+ |
|
| 237 |
+ |
/** |
| 238 |
+ |
* Resize array, if necessary, to be able to hold given index |
| 239 |
+ |
*/ |
| 240 |
+ |
private void grow(int index) { |
| 241 |
+ |
int newlen = queue.length; |
| 242 |
+ |
if (index < newlen) // don't need to grow |
| 243 |
+ |
return; |
| 244 |
+ |
if (index == Integer.MAX_VALUE) |
| 245 |
+ |
throw new OutOfMemoryError(); |
| 246 |
+ |
while (newlen <= index) { |
| 247 |
+ |
if (newlen >= Integer.MAX_VALUE / 2) // avoid overflow |
| 248 |
+ |
newlen = Integer.MAX_VALUE; |
| 249 |
+ |
else |
| 250 |
+ |
newlen <<= 2; |
| 251 |
+ |
} |
| 252 |
+ |
Object[] newQueue = new Object[newlen]; |
| 253 |
+ |
System.arraycopy(queue, 0, newQueue, 0, queue.length); |
| 254 |
+ |
queue = newQueue; |
| 255 |
+ |
} |
| 256 |
+ |
|
| 257 |
|
// Queue Methods |
| 258 |
|
|
| 259 |
|
/** |
| 260 |
< |
* Remove and return the minimal element from this priority queue if |
| 145 |
< |
* it contains one or more elements, otherwise <tt>null</tt>. The term |
| 146 |
< |
* <i>minimal</i> is defined according to this priority queue's order. |
| 260 |
> |
* Add the specified element to this priority queue. |
| 261 |
|
* |
| 262 |
< |
* @return the minimal element from this priority queue if it contains |
| 263 |
< |
* one or more elements, otherwise <tt>null</tt>. |
| 262 |
> |
* @return <tt>true</tt> |
| 263 |
> |
* @throws ClassCastException if the specified element cannot be compared |
| 264 |
> |
* with elements currently in the priority queue according |
| 265 |
> |
* to the priority queue's ordering. |
| 266 |
> |
* @throws NullPointerException if the specified element is <tt>null</tt>. |
| 267 |
|
*/ |
| 268 |
+ |
public boolean offer(E o) { |
| 269 |
+ |
if (o == null) |
| 270 |
+ |
throw new NullPointerException(); |
| 271 |
+ |
modCount++; |
| 272 |
+ |
++size; |
| 273 |
+ |
|
| 274 |
+ |
// Grow backing store if necessary |
| 275 |
+ |
if (size >= queue.length) |
| 276 |
+ |
grow(size); |
| 277 |
+ |
|
| 278 |
+ |
queue[size] = o; |
| 279 |
+ |
fixUp(size); |
| 280 |
+ |
return true; |
| 281 |
+ |
} |
| 282 |
+ |
|
| 283 |
|
public E poll() { |
| 284 |
|
if (size == 0) |
| 285 |
|
return null; |
| 286 |
< |
return remove(1); |
| 286 |
> |
return (E) remove(1); |
| 287 |
|
} |
| 288 |
|
|
| 157 |
– |
/** |
| 158 |
– |
* Return, but do not remove, the minimal element from the priority queue, |
| 159 |
– |
* or <tt>null</tt> if the queue is empty. The term <i>minimal</i> is |
| 160 |
– |
* defined according to this priority queue's order. This method returns |
| 161 |
– |
* the same object reference that would be returned by by the |
| 162 |
– |
* <tt>poll</tt> method. The two methods differ in that this method |
| 163 |
– |
* does not remove the element from the priority queue. |
| 164 |
– |
* |
| 165 |
– |
* @return the minimal element from this priority queue if it contains |
| 166 |
– |
* one or more elements, otherwise <tt>null</tt>. |
| 167 |
– |
*/ |
| 289 |
|
public E peek() { |
| 290 |
< |
return queue[1]; |
| 290 |
> |
return (E) queue[1]; |
| 291 |
|
} |
| 292 |
|
|
| 293 |
|
// Collection Methods |
| 294 |
|
|
| 295 |
+ |
// these first two override just to get the throws docs |
| 296 |
+ |
|
| 297 |
|
/** |
| 298 |
< |
* Removes a single instance of the specified element from this priority |
| 176 |
< |
* queue, if it is present. Returns true if this collection contained the |
| 177 |
< |
* specified element (or equivalently, if this collection changed as a |
| 178 |
< |
* result of the call). |
| 179 |
< |
* |
| 180 |
< |
* @param o element to be removed from this collection, if present. |
| 181 |
< |
* @return <tt>true</tt> if this collection changed as a result of the |
| 182 |
< |
* call |
| 298 |
> |
* @throws NullPointerException if the specified element is <tt>null</tt>. |
| 299 |
|
* @throws ClassCastException if the specified element cannot be compared |
| 300 |
< |
* with elements currently in the priority queue according |
| 301 |
< |
* to the priority queue's ordering. |
| 186 |
< |
* @throws NullPointerException if the specified element is null. |
| 300 |
> |
* with elements currently in the priority queue according |
| 301 |
> |
* to the priority queue's ordering. |
| 302 |
|
*/ |
| 303 |
< |
public boolean remove(Object element) { |
| 304 |
< |
if (element == null) |
| 305 |
< |
throw new NullPointerException(); |
| 303 |
> |
public boolean add(E o) { |
| 304 |
> |
return super.add(o); |
| 305 |
> |
} |
| 306 |
> |
|
| 307 |
> |
/** |
| 308 |
> |
* @throws ClassCastException if any element cannot be compared |
| 309 |
> |
* with elements currently in the priority queue according |
| 310 |
> |
* to the priority queue's ordering. |
| 311 |
> |
* @throws NullPointerException if <tt>c</tt> or any element in <tt>c</tt> |
| 312 |
> |
* is <tt>null</tt> |
| 313 |
> |
*/ |
| 314 |
> |
public boolean addAll(Collection<? extends E> c) { |
| 315 |
> |
return super.addAll(c); |
| 316 |
> |
} |
| 317 |
> |
|
| 318 |
> |
public boolean remove(Object o) { |
| 319 |
> |
if (o == null) |
| 320 |
> |
return false; |
| 321 |
|
|
| 322 |
|
if (comparator == null) { |
| 323 |
|
for (int i = 1; i <= size; i++) { |
| 324 |
< |
if (((Comparable)queue[i]).compareTo(element) == 0) { |
| 324 |
> |
if (((Comparable<E>)queue[i]).compareTo((E)o) == 0) { |
| 325 |
|
remove(i); |
| 326 |
|
return true; |
| 327 |
|
} |
| 328 |
|
} |
| 329 |
|
} else { |
| 330 |
|
for (int i = 1; i <= size; i++) { |
| 331 |
< |
if (comparator.compare(queue[i], (E) element) == 0) { |
| 331 |
> |
if (comparator.compare((E)queue[i], (E)o) == 0) { |
| 332 |
|
remove(i); |
| 333 |
|
return true; |
| 334 |
|
} |
| 337 |
|
return false; |
| 338 |
|
} |
| 339 |
|
|
| 210 |
– |
/** |
| 211 |
– |
* Returns an iterator over the elements in this priority queue. The |
| 212 |
– |
* first element returned by this iterator is the same element that |
| 213 |
– |
* would be returned by a call to <tt>peek</tt>. |
| 214 |
– |
* |
| 215 |
– |
* @return an <tt>Iterator</tt> over the elements in this priority queue. |
| 216 |
– |
*/ |
| 340 |
|
public Iterator<E> iterator() { |
| 341 |
< |
return new Itr(); |
| 341 |
> |
return new Itr(); |
| 342 |
|
} |
| 343 |
|
|
| 344 |
|
private class Itr implements Iterator<E> { |
| 345 |
< |
/** |
| 346 |
< |
* Index (into queue array) of element to be returned by |
| 345 |
> |
/** |
| 346 |
> |
* Index (into queue array) of element to be returned by |
| 347 |
|
* subsequent call to next. |
| 348 |
< |
*/ |
| 349 |
< |
int cursor = 1; |
| 348 |
> |
*/ |
| 349 |
> |
private int cursor = 1; |
| 350 |
|
|
| 351 |
< |
/** |
| 352 |
< |
* Index of element returned by most recent call to next or |
| 353 |
< |
* previous. Reset to 0 if this element is deleted by a call |
| 354 |
< |
* to remove. |
| 355 |
< |
*/ |
| 356 |
< |
int lastRet = 0; |
| 357 |
< |
|
| 358 |
< |
/** |
| 359 |
< |
* The modCount value that the iterator believes that the backing |
| 360 |
< |
* List should have. If this expectation is violated, the iterator |
| 361 |
< |
* has detected concurrent modification. |
| 362 |
< |
*/ |
| 363 |
< |
int expectedModCount = modCount; |
| 241 |
< |
|
| 242 |
< |
public boolean hasNext() { |
| 243 |
< |
return cursor <= size; |
| 244 |
< |
} |
| 351 |
> |
/** |
| 352 |
> |
* Index of element returned by most recent call to next or |
| 353 |
> |
* previous. Reset to 0 if this element is deleted by a call |
| 354 |
> |
* to remove. |
| 355 |
> |
*/ |
| 356 |
> |
private int lastRet = 0; |
| 357 |
> |
|
| 358 |
> |
/** |
| 359 |
> |
* The modCount value that the iterator believes that the backing |
| 360 |
> |
* List should have. If this expectation is violated, the iterator |
| 361 |
> |
* has detected concurrent modification. |
| 362 |
> |
*/ |
| 363 |
> |
private int expectedModCount = modCount; |
| 364 |
|
|
| 365 |
< |
public E next() { |
| 365 |
> |
public boolean hasNext() { |
| 366 |
> |
return cursor <= size; |
| 367 |
> |
} |
| 368 |
> |
|
| 369 |
> |
public E next() { |
| 370 |
|
checkForComodification(); |
| 371 |
|
if (cursor > size) |
| 372 |
< |
throw new NoSuchElementException(); |
| 373 |
< |
E result = queue[cursor]; |
| 372 |
> |
throw new NoSuchElementException(); |
| 373 |
> |
E result = (E) queue[cursor]; |
| 374 |
|
lastRet = cursor++; |
| 375 |
|
return result; |
| 376 |
< |
} |
| 376 |
> |
} |
| 377 |
|
|
| 378 |
< |
public void remove() { |
| 379 |
< |
if (lastRet == 0) |
| 380 |
< |
throw new IllegalStateException(); |
| 378 |
> |
public void remove() { |
| 379 |
> |
if (lastRet == 0) |
| 380 |
> |
throw new IllegalStateException(); |
| 381 |
|
checkForComodification(); |
| 382 |
|
|
| 383 |
|
PriorityQueue.this.remove(lastRet); |
| 385 |
|
cursor--; |
| 386 |
|
lastRet = 0; |
| 387 |
|
expectedModCount = modCount; |
| 388 |
< |
} |
| 388 |
> |
} |
| 389 |
|
|
| 390 |
< |
final void checkForComodification() { |
| 391 |
< |
if (modCount != expectedModCount) |
| 392 |
< |
throw new ConcurrentModificationException(); |
| 393 |
< |
} |
| 390 |
> |
final void checkForComodification() { |
| 391 |
> |
if (modCount != expectedModCount) |
| 392 |
> |
throw new ConcurrentModificationException(); |
| 393 |
> |
} |
| 394 |
|
} |
| 395 |
|
|
| 396 |
|
/** |
| 397 |
|
* Returns the number of elements in this priority queue. |
| 398 |
< |
* |
| 398 |
> |
* |
| 399 |
|
* @return the number of elements in this priority queue. |
| 400 |
|
*/ |
| 401 |
|
public int size() { |
| 403 |
|
} |
| 404 |
|
|
| 405 |
|
/** |
| 283 |
– |
* Add the specified element to this priority queue. |
| 284 |
– |
* |
| 285 |
– |
* @param element the element to add. |
| 286 |
– |
* @return true |
| 287 |
– |
* @throws ClassCastException if the specified element cannot be compared |
| 288 |
– |
* with elements currently in the priority queue according |
| 289 |
– |
* to the priority queue's ordering. |
| 290 |
– |
* @throws NullPointerException if the specified element is null. |
| 291 |
– |
*/ |
| 292 |
– |
public boolean offer(E element) { |
| 293 |
– |
if (element == null) |
| 294 |
– |
throw new NullPointerException(); |
| 295 |
– |
modCount++; |
| 296 |
– |
|
| 297 |
– |
// Grow backing store if necessary |
| 298 |
– |
if (++size == queue.length) { |
| 299 |
– |
E[] newQueue = new E[2 * queue.length]; |
| 300 |
– |
System.arraycopy(queue, 0, newQueue, 0, size); |
| 301 |
– |
queue = newQueue; |
| 302 |
– |
} |
| 303 |
– |
|
| 304 |
– |
queue[size] = element; |
| 305 |
– |
fixUp(size); |
| 306 |
– |
return true; |
| 307 |
– |
} |
| 308 |
– |
|
| 309 |
– |
/** |
| 406 |
|
* Remove all elements from the priority queue. |
| 407 |
|
*/ |
| 408 |
|
public void clear() { |
| 426 |
|
assert i <= size; |
| 427 |
|
modCount++; |
| 428 |
|
|
| 429 |
< |
E result = queue[i]; |
| 429 |
> |
E result = (E) queue[i]; |
| 430 |
|
queue[i] = queue[size]; |
| 431 |
|
queue[size--] = null; // Drop extra ref to prevent memory leak |
| 432 |
|
if (i <= size) |
| 447 |
|
if (comparator == null) { |
| 448 |
|
while (k > 1) { |
| 449 |
|
int j = k >> 1; |
| 450 |
< |
if (((Comparable)queue[j]).compareTo(queue[k]) <= 0) |
| 450 |
> |
if (((Comparable<E>)queue[j]).compareTo((E)queue[k]) <= 0) |
| 451 |
|
break; |
| 452 |
< |
E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
| 452 |
> |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
| 453 |
|
k = j; |
| 454 |
|
} |
| 455 |
|
} else { |
| 456 |
|
while (k > 1) { |
| 457 |
|
int j = k >> 1; |
| 458 |
< |
if (comparator.compare(queue[j], queue[k]) <= 0) |
| 458 |
> |
if (comparator.compare((E)queue[j], (E)queue[k]) <= 0) |
| 459 |
|
break; |
| 460 |
< |
E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
| 460 |
> |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
| 461 |
|
k = j; |
| 462 |
|
} |
| 463 |
|
} |
| 476 |
|
int j; |
| 477 |
|
if (comparator == null) { |
| 478 |
|
while ((j = k << 1) <= size) { |
| 479 |
< |
if (j<size && ((Comparable)queue[j]).compareTo(queue[j+1]) > 0) |
| 479 |
> |
if (j<size && ((Comparable<E>)queue[j]).compareTo((E)queue[j+1]) > 0) |
| 480 |
|
j++; // j indexes smallest kid |
| 481 |
< |
if (((Comparable)queue[k]).compareTo(queue[j]) <= 0) |
| 481 |
> |
if (((Comparable<E>)queue[k]).compareTo((E)queue[j]) <= 0) |
| 482 |
|
break; |
| 483 |
< |
E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
| 483 |
> |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
| 484 |
|
k = j; |
| 485 |
|
} |
| 486 |
|
} else { |
| 487 |
|
while ((j = k << 1) <= size) { |
| 488 |
< |
if (j < size && comparator.compare(queue[j], queue[j+1]) > 0) |
| 488 |
> |
if (j < size && comparator.compare((E)queue[j], (E)queue[j+1]) > 0) |
| 489 |
|
j++; // j indexes smallest kid |
| 490 |
< |
if (comparator.compare(queue[k], queue[j]) <= 0) |
| 490 |
> |
if (comparator.compare((E)queue[k], (E)queue[j]) <= 0) |
| 491 |
|
break; |
| 492 |
< |
E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
| 492 |
> |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
| 493 |
|
k = j; |
| 494 |
|
} |
| 495 |
|
} |
| 496 |
|
} |
| 497 |
|
|
| 498 |
< |
/** |
| 403 |
< |
* Returns the comparator associated with this priority queue, or |
| 404 |
< |
* <tt>null</tt> if it uses its elements' natural ordering. |
| 405 |
< |
* |
| 406 |
< |
* @return the comparator associated with this priority queue, or |
| 407 |
< |
* <tt>null</tt> if it uses its elements' natural ordering. |
| 408 |
< |
*/ |
| 409 |
< |
Comparator comparator() { |
| 498 |
> |
public Comparator<? super E> comparator() { |
| 499 |
|
return comparator; |
| 500 |
|
} |
| 501 |
|
|
| 506 |
|
* @serialData The length of the array backing the instance is |
| 507 |
|
* emitted (int), followed by all of its elements (each an |
| 508 |
|
* <tt>Object</tt>) in the proper order. |
| 509 |
+ |
* @param s the stream |
| 510 |
|
*/ |
| 511 |
< |
private synchronized void writeObject(java.io.ObjectOutputStream s) |
| 511 |
> |
private void writeObject(java.io.ObjectOutputStream s) |
| 512 |
|
throws java.io.IOException{ |
| 513 |
< |
// Write out element count, and any hidden stuff |
| 514 |
< |
s.defaultWriteObject(); |
| 513 |
> |
// Write out element count, and any hidden stuff |
| 514 |
> |
s.defaultWriteObject(); |
| 515 |
|
|
| 516 |
|
// Write out array length |
| 517 |
|
s.writeInt(queue.length); |
| 518 |
|
|
| 519 |
< |
// Write out all elements in the proper order. |
| 520 |
< |
for (int i=0; i<size; i++) |
| 519 |
> |
// Write out all elements in the proper order. |
| 520 |
> |
for (int i=0; i<size; i++) |
| 521 |
|
s.writeObject(queue[i]); |
| 522 |
|
} |
| 523 |
|
|
| 524 |
|
/** |
| 525 |
|
* Reconstitute the <tt>ArrayList</tt> instance from a stream (that is, |
| 526 |
|
* deserialize it). |
| 527 |
+ |
* @param s the stream |
| 528 |
|
*/ |
| 529 |
< |
private synchronized void readObject(java.io.ObjectInputStream s) |
| 529 |
> |
private void readObject(java.io.ObjectInputStream s) |
| 530 |
|
throws java.io.IOException, ClassNotFoundException { |
| 531 |
< |
// Read in size, and any hidden stuff |
| 532 |
< |
s.defaultReadObject(); |
| 531 |
> |
// Read in size, and any hidden stuff |
| 532 |
> |
s.defaultReadObject(); |
| 533 |
|
|
| 534 |
|
// Read in array length and allocate array |
| 535 |
|
int arrayLength = s.readInt(); |
| 536 |
< |
queue = new E[arrayLength]; |
| 536 |
> |
queue = new Object[arrayLength]; |
| 537 |
|
|
| 538 |
< |
// Read in all elements in the proper order. |
| 539 |
< |
for (int i=0; i<size; i++) |
| 540 |
< |
queue[i] = (E)s.readObject(); |
| 538 |
> |
// Read in all elements in the proper order. |
| 539 |
> |
for (int i=0; i<size; i++) |
| 540 |
> |
queue[i] = s.readObject(); |
| 541 |
|
} |
| 542 |
|
|
| 543 |
|
} |
| 544 |
+ |
|
