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java.lang.Object | +--java.util.AbstractCollection | +--edu.emory.mathcs.util.AbstractQueue | +--edu.emory.mathcs.util.concurrent.PriorityBlockingQueue
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). |
|
PriorityBlockingQueue(java.util.Collection c)
Creates a PriorityBlockingQueue containing the elements in the specified collection. |
|
PriorityBlockingQueue(int initialCapacity)
Creates a PriorityBlockingQueue with the specified initial capacity that orders its elements according to their natural ordering (using Comparable). |
|
PriorityBlockingQueue(int initialCapacity,
java.util.Comparator comparator)
Creates a PriorityBlockingQueue with the specified initial capacity that orders its elements according to the specified comparator. |
Method Summary | |
boolean |
add(java.lang.Object o)
Adds the specified element to this queue. |
void |
clear()
Atomically removes all of the elements from this queue. |
java.util.Comparator |
comparator()
Returns the comparator used to order this collection, or null if this collection is sorted according to its elements natural ordering (using Comparable). |
boolean |
contains(java.lang.Object o)
|
int |
drainTo(java.util.Collection c)
Removes all available elements from this queue and adds them into the given collection. |
int |
drainTo(java.util.Collection c,
int maxElements)
Removes at most the given number of available elements from this queue and adds them into the given collection. |
java.util.Iterator |
iterator()
Returns an iterator over the elements in this queue. |
boolean |
offer(java.lang.Object o)
Inserts the specified element into this priority queue. |
boolean |
offer(java.lang.Object o,
long timeout,
TimeUnit unit)
Inserts the specified element into this priority queue. |
java.lang.Object |
peek()
Retrieves, but does not remove, the head of this queue, returning null if this queue is empty. |
java.lang.Object |
poll()
Retrieves and removes the head of this queue, or null if this queue is empty. |
java.lang.Object |
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. |
void |
put(java.lang.Object o)
Adds the specified element to this priority queue. |
int |
remainingCapacity()
Always returns Integer.MAX_VALUE because a PriorityBlockingQueue is not capacity constrained. |
boolean |
remove(java.lang.Object o)
Removes a single instance of the specified element from this queue, if it is present. |
int |
size()
|
java.lang.Object |
take()
Retrieves and removes the head of this queue, waiting if no elements are present on this queue. |
java.lang.Object[] |
toArray()
|
java.lang.Object[] |
toArray(java.lang.Object[] a)
|
java.lang.String |
toString()
|
Methods inherited from class edu.emory.mathcs.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 edu.emory.mathcs.util.Queue |
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.
java.lang.IllegalArgumentException
- if initialCapacity is less
than 1public PriorityBlockingQueue(int initialCapacity, java.util.Comparator 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.
java.lang.IllegalArgumentException
- if initialCapacity is less
than 1public PriorityBlockingQueue(java.util.Collection 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.
java.lang.ClassCastException
- if elements of the specified collection
cannot be compared to one another according to the priority
queue's ordering.
java.lang.NullPointerException
- if c or any element within it
is nullMethod Detail |
public boolean add(java.lang.Object o)
add
in interface BlockingQueue
add
in class AbstractQueue
o
- the element to add
java.lang.NullPointerException
- if the specified element is null.
java.lang.ClassCastException
- if the specified element cannot be compared
with elements currently in the priority queue according
to the priority queue's ordering.public java.util.Comparator comparator()
public boolean offer(java.lang.Object o)
offer
in interface BlockingQueue
o
- the element to add
java.lang.ClassCastException
- if the specified element cannot be compared
with elements currently in the priority queue according
to the priority queue's ordering.
java.lang.NullPointerException
- if the specified element is null.public void put(java.lang.Object o)
put
in interface BlockingQueue
o
- the element to add
java.lang.ClassCastException
- if the element cannot be compared
with elements currently in the priority queue according
to the priority queue's ordering.
java.lang.NullPointerException
- if the specified element is null.public boolean offer(java.lang.Object o, long timeout, TimeUnit unit)
offer
in interface BlockingQueue
o
- the element to addtimeout
- This parameter is ignored as the method never blocksunit
- This parameter is ignored as the method never blocks
java.lang.ClassCastException
- if the element cannot be compared
with elements currently in the priority queue according
to the priority queue's ordering.
java.lang.NullPointerException
- if the specified element is null.public java.lang.Object take() throws java.lang.InterruptedException
BlockingQueue
take
in interface BlockingQueue
java.lang.InterruptedException
- if interrupted while waiting.public java.lang.Object poll()
Queue
poll
in interface Queue
public java.lang.Object poll(long timeout, TimeUnit unit) throws java.lang.InterruptedException
BlockingQueue
poll
in interface BlockingQueue
timeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameter
java.lang.InterruptedException
- if interrupted while waiting.public java.lang.Object peek()
Queue
peek
in interface Queue
public int size()
size
in interface java.util.Collection
size
in class java.util.AbstractCollection
public int remainingCapacity()
remainingCapacity
in interface BlockingQueue
public boolean remove(java.lang.Object o)
remove
in interface java.util.Collection
remove
in class java.util.AbstractCollection
public boolean contains(java.lang.Object o)
contains
in interface java.util.Collection
contains
in class java.util.AbstractCollection
public java.lang.Object[] toArray()
toArray
in interface java.util.Collection
toArray
in class java.util.AbstractCollection
public java.lang.String toString()
toString
in class java.util.AbstractCollection
public int drainTo(java.util.Collection c)
BlockingQueue
drainTo
in interface BlockingQueue
c
- the collection to transfer elements into
public int drainTo(java.util.Collection c, int maxElements)
BlockingQueue
drainTo
in interface BlockingQueue
c
- the collection to transfer elements intomaxElements
- the maximum number of elements to transfer
public void clear()
clear
in interface java.util.Collection
clear
in class AbstractQueue
public java.lang.Object[] toArray(java.lang.Object[] a)
toArray
in interface java.util.Collection
toArray
in class java.util.AbstractCollection
public java.util.Iterator iterator()
ConcurrentModificationException
upon detected
interference.
iterator
in interface java.util.Collection
iterator
in class java.util.AbstractCollection
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