java.util.AbstractCollection<E>
java.util.AbstractQueue<E>
java.util.concurrent.PriorityBlockingQueue<E>
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JavaTM 2 Platform Standard Ed. 5.0 |
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java.lang.Object
E - the type of elements held in this collectionpublic class PriorityBlockingQueue<E>
An unbounded blocking queue that uses
the same ordering rules as class PriorityQueue and supplies
blocking retrieval operations. While this queue is logically
unbounded, attempted additions may fail due to resource exhaustion
(causing OutOfMemoryError). This class does not permit
null elements. A priority queue relying on natural
ordering also does not permit insertion of non-comparable objects
(doing so results in ClassCastException).
This class and its iterator implement all of the
optional methods of the Collection and Iterator interfaces.
The Iterator provided in method iterator() is
not guaranteed to traverse the elements of the
PriorityBlockingQueue in any particular order. If you need ordered
traversal, consider using Arrays.sort(pq.toArray()).
This class is a member of the Java Collections Framework.
| Constructor Summary | |
|---|---|
PriorityBlockingQueue()
Creates a PriorityBlockingQueue with the default initial capacity (11) that orders its elements according to their natural ordering (using Comparable). |
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PriorityBlockingQueue(Collection<? extends E> c)
Creates a PriorityBlockingQueue containing the elements in the specified collection. |
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PriorityBlockingQueue(int initialCapacity)
Creates a PriorityBlockingQueue with the specified initial capacity that orders its elements according to their natural ordering (using Comparable). |
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PriorityBlockingQueue(int initialCapacity,
Comparator<? super E> comparator)
Creates a PriorityBlockingQueue with the specified initial capacity that orders its elements according to the specified comparator. |
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| Method Summary | ||
|---|---|---|
boolean |
add(E o)
Adds the specified element to this queue. |
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void |
clear()
Atomically removes all of the elements from this queue. |
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Comparator<? super E> |
comparator()
Returns the comparator used to order this collection, or null if this collection is sorted according to its elements natural ordering (using Comparable). |
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boolean |
contains(Object o)
Returns true if this collection contains the specified element. |
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int |
drainTo(Collection<? super E> c)
Removes all available elements from this queue and adds them into the given collection. |
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int |
drainTo(Collection<? super E> c,
int maxElements)
Removes at most the given number of available elements from this queue and adds them into the given collection. |
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Iterator<E> |
iterator()
Returns an iterator over the elements in this queue. |
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boolean |
offer(E o)
Inserts the specified element into this priority queue. |
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boolean |
offer(E o,
long timeout,
TimeUnit unit)
Inserts the specified element into this priority queue. |
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E |
peek()
Retrieves, but does not remove, the head of this queue, returning null if this queue is empty. |
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E |
poll()
Retrieves and removes the head of this queue, or null if this queue is empty. |
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E |
poll(long timeout,
TimeUnit unit)
Retrieves and removes the head of this queue, waiting if necessary up to the specified wait time if no elements are present on this queue. |
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void |
put(E o)
Adds the specified element to this priority queue. |
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int |
remainingCapacity()
Always returns Integer.MAX_VALUE because a PriorityBlockingQueue is not capacity constrained. |
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boolean |
remove(Object o)
Removes a single instance of the specified element from this queue, if it is present. |
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int |
size()
Returns the number of elements in this collection. |
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E |
take()
Retrieves and removes the head of this queue, waiting if no elements are present on this queue. |
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Object[] |
toArray()
Returns an array containing all of the elements in this collection. |
|
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toArray(T[] a)
Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. |
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String |
toString()
Returns a string representation of this collection. |
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| Methods inherited from class java.util.AbstractQueue |
|---|
addAll, element, remove |
| Methods inherited from class java.util.AbstractCollection |
|---|
containsAll, isEmpty, removeAll, retainAll |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
| Methods inherited from interface java.util.Queue |
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element, remove |
| Methods inherited from interface java.util.Collection |
|---|
addAll, containsAll, equals, hashCode, isEmpty, removeAll, retainAll |
| Constructor Detail |
|---|
public PriorityBlockingQueue()
public PriorityBlockingQueue(int initialCapacity)
initialCapacity - the initial capacity for this priority queue.
IllegalArgumentException - if initialCapacity is less
than 1
public PriorityBlockingQueue(int initialCapacity,
Comparator<? super E> comparator)
initialCapacity - the initial capacity for this priority queue.comparator - the comparator used to order this priority queue.
If null then the order depends on the elements' natural
ordering.
IllegalArgumentException - if initialCapacity is less
than 1public PriorityBlockingQueue(Collection<? extends E> c)
SortedSet or a PriorityQueue, this 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'
natural order. Otherwise, this priority queue is ordered
according to its elements' natural order.
c - the collection whose elements are to be placed
into this priority queue.
ClassCastException - if elements of the specified collection
cannot be compared to one another according to the priority
queue's ordering.
NullPointerException - if c or any element within it
is null| Method Detail |
|---|
public boolean add(E o)
add in interface Collection<E>add in interface BlockingQueue<E>add in class AbstractQueue<E>o - the element to add
NullPointerException - if the specified element is null.
ClassCastException - if the specified element cannot be compared
with elements currently in the priority queue according
to the priority queue's ordering.public Comparator<? super E> comparator()
public boolean offer(E o)
offer in interface BlockingQueue<E>offer in interface Queue<E>o - the element to add
ClassCastException - if the specified element cannot be compared
with elements currently in the priority queue according
to the priority queue's ordering.
NullPointerException - if the specified element is null.public void put(E o)
put in interface BlockingQueue<E>o - the element to add
ClassCastException - if the element cannot be compared
with elements currently in the priority queue according
to the priority queue's ordering.
NullPointerException - if the specified element is null.
public boolean offer(E o,
long timeout,
TimeUnit unit)
offer in interface BlockingQueue<E>o - the element to addtimeout - This parameter is ignored as the method never blocksunit - This parameter is ignored as the method never blocks
ClassCastException - if the element cannot be compared
with elements currently in the priority queue according
to the priority queue's ordering.
NullPointerException - if the specified element is null.
public E take()
throws InterruptedException
BlockingQueue
take in interface BlockingQueue<E>InterruptedException - if interrupted while waiting.public E poll()
Queue
poll in interface Queue<E>
public E poll(long timeout,
TimeUnit unit)
throws InterruptedException
BlockingQueue
poll in interface BlockingQueue<E>timeout - how long to wait before giving up, in units of
unitunit - a TimeUnit determining how to interpret the
timeout parameter
InterruptedException - if interrupted while waiting.public E peek()
Queue
peek in interface Queue<E>public int size()
AbstractCollection
size in interface Collection<E>size in class AbstractCollection<E>public int remainingCapacity()
remainingCapacity in interface BlockingQueue<E>public boolean remove(Object o)
remove in interface Collection<E>remove in class AbstractCollection<E>o - element to be removed from this collection, if present.
public boolean contains(Object o)
AbstractCollectionThis implementation iterates over the elements in the collection, checking each element in turn for equality with the specified element.
contains in interface Collection<E>contains in class AbstractCollection<E>o - object to be checked for containment in this collection.
public Object[] toArray()
AbstractCollectionThis implementation allocates the array to be returned, and iterates over the elements in the collection, storing each object reference in the next consecutive element of the array, starting with element 0.
toArray in interface Collection<E>toArray in class AbstractCollection<E>public String toString()
AbstractCollectionThis implementation creates an empty string buffer, appends a left square bracket, and iterates over the collection appending the string representation of each element in turn. After appending each element except the last, the string ", " is appended. Finally a right bracket is appended. A string is obtained from the string buffer, and returned.
toString in class AbstractCollection<E>public int drainTo(Collection<? super E> c)
BlockingQueue
drainTo in interface BlockingQueue<E>c - the collection to transfer elements into
public int drainTo(Collection<? super E> c,
int maxElements)
BlockingQueue
drainTo in interface BlockingQueue<E>c - the collection to transfer elements intomaxElements - the maximum number of elements to transfer
public void clear()
clear in interface Collection<E>clear in class AbstractQueue<E>public <T> T[] toArray(T[] a)
AbstractCollectionIf the collection fits in the specified array with room to spare (i.e., the array has more elements than the collection), the element in the array immediately following the end of the collection is set to null. This is useful in determining the length of the collection only if the caller knows that the collection does not contain any null elements.)
If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order.
This implementation checks if the array is large enough to contain the collection; if not, it allocates a new array of the correct size and type (using reflection). Then, it iterates over the collection, storing each object reference in the next consecutive element of the array, starting with element 0. If the array is larger than the collection, a null is stored in the first location after the end of the collection.
toArray in interface Collection<E>toArray in class AbstractCollection<E>a - the array into which the elements of the collection are to
be stored, if it is big enough; otherwise, a new array of the
same runtime type is allocated for this purpose.
public Iterator<E> iterator()
ConcurrentModificationException upon detected
interference.
iterator in interface Iterable<E>iterator in interface Collection<E>iterator in class AbstractCollection<E>
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JavaTM 2 Platform Standard Ed. 5.0 |
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Copyright 2004 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.