PriorityBlockingQueue

java.lang.Object
- java.util.AbstractCollection<E>
- - java.util.AbstractQueue<E>
  - - java.util.concurrent.PriorityBlockingQueue<E>

类型参数:

E - the type of elements held in this collection

所有已实现的接口:

Serializable, Iterable<E>, Collection<E>, BlockingQueue<E>, Queue<E>
```
public class PriorityBlockingQueue<E>
extends AbstractQueue<E>
implements BlockingQueue<E>, Serializable
```
An unbounded BlockingQueue 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 Comparable 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()). Also, method drainTo can be used to remove some or all elements in priority order and place them in another collection.
Operations on this class make no guarantees about the ordering of elements with equal priority. If you need to enforce an ordering, you can define custom classes or comparators that use a secondary key to break ties in primary priority values. For example, here is a class that applies first-in-first-out tie-breaking to comparable elements. To use it, you would insert a new FIFOEntry(anEntry) instead of a plain entry object.
```
 
 class FIFOEntry<E extends Comparable<? super E>>
     implements Comparable<FIFOEntry<E>> {
   static final AtomicLong seq = new AtomicLong(0);
   final long seqNum;
   final E entry;
   public FIFOEntry(E entry) {
     seqNum = seq.getAndIncrement();
     this.entry = entry;
   }
   public E getEntry() { return entry; }
   public int compareTo(FIFOEntry<E> other) {
     int res = entry.compareTo(other.entry);
     if (res == 0 && other.entry != this.entry)
       res = (seqNum < other.seqNum ? -1 : 1);
     return res;
   }
 }
```
This class is a member of the Java Collections Framework.
从以下版本开始:

1.5

另请参阅:

序列化表格

构造器概要

构造器
构造器	说明
`PriorityBlockingQueue()`	Creates a `PriorityBlockingQueue` with the default initial capacity (11) that orders its elements according to their Comparable.
`PriorityBlockingQueue(int initialCapacity)`	Creates a `PriorityBlockingQueue` with the specified initial capacity that orders its elements according to their Comparable.
`PriorityBlockingQueue(int initialCapacity, Comparator<? super E> comparator)`	Creates a `PriorityBlockingQueue` with the specified initial capacity that orders its elements according to the specified comparator.
`PriorityBlockingQueue(Collection<? extends E> c)`	Creates a `PriorityBlockingQueue` containing the elements in the specified collection.

方法概要

所有方法实例方法具体方法
限定符和类型	方法	说明
`boolean`	`add(E e)`	Inserts the specified element into this priority queue.
`void`	`clear()`	Atomically removes all of the elements from this queue.
`Comparator<? super E>`	`comparator()`	Returns the comparator used to order the elements in this queue, or `null` if this queue uses the Comparable of its elements.
`boolean`	`contains(Object o)`	Returns `true` if this queue contains the specified element.
`int`	`drainTo(Collection<? super E> c)`	Removes all available elements from this queue and adds them to the given collection.
`int`	`drainTo(Collection<? super E> c, int maxElements)`	Removes at most the given number of available elements from this queue and adds them to the given collection.
`Iterator<E>`	`iterator()`	Returns an iterator over the elements in this queue.
`boolean`	`offer(E e)`	Inserts the specified element into this priority queue.
`boolean`	`offer(E e, long timeout, TimeUnit unit)`	Inserts the specified element into this priority queue.
`E`	`peek()`	Retrieves, but does not remove, the head of this queue, or returns `null` if this queue is empty.
`E`	`poll()`	Retrieves and removes the head of this queue, or returns `null` if this queue is empty.
`E`	`poll(long timeout, TimeUnit unit)`	Retrieves and removes the head of this queue, waiting up to the specified wait time if necessary for an element to become available.
`void`	`put(E e)`	Inserts the specified element into this priority queue.
`int`	`remainingCapacity()`	Always returns `Integer.MAX_VALUE` because a `PriorityBlockingQueue` is not capacity constrained.
`boolean`	`remove(Object o)`	Removes a single instance of the specified element from this queue, if it is present.
`int`	`size()`	Returns the number of elements in this collection.
`Spliterator<E>`	`spliterator()`	Returns a `Spliterator` over the elements in this queue.
`E`	`take()`	Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.
`Object[]`	`toArray()`	Returns an array containing all of the elements in this queue.
`<T> T[]`	`toArray(T[] a)`	Returns an array containing all of the elements in this queue; the runtime type of the returned array is that of the specified array.
`String`	`toString()`	Returns a string representation of this collection.

从类继承的方法 java.util.AbstractCollection
containsAll, isEmpty, removeAll, retainAll

从类继承的方法 java.util.AbstractQueue
addAll, element, remove

从接口继承的方法 java.util.Collection
addAll, containsAll, equals, hashCode, isEmpty, parallelStream, removeAll, removeIf, retainAll, stream

从接口继承的方法 java.lang.Iterable
forEach

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

从接口继承的方法 java.util.Queue
element, remove

- 构造器详细资料
  - PriorityBlockingQueue
```
public PriorityBlockingQueue()
```
    Creates a PriorityBlockingQueue with the default initial capacity (11) that orders its elements according to their Comparable.
  - PriorityBlockingQueue
```
public PriorityBlockingQueue(int initialCapacity)
```
    Creates a PriorityBlockingQueue with the specified initial capacity that orders its elements according to their Comparable.
    
    参数:
    
    initialCapacity - the initial capacity for this priority queue
    
    抛出:
    
    IllegalArgumentException - if initialCapacity is less than 1
  - PriorityBlockingQueue
```
public PriorityBlockingQueue(int initialCapacity,
                             Comparator<? super E> comparator)
```
    Creates a PriorityBlockingQueue with the specified initial capacity that orders its elements according to the specified comparator.
    
    参数:
    
    initialCapacity - the initial capacity for this priority queue
    
    comparator - the comparator that will be used to order this priority queue. If null, the Comparable of the elements will be used.
    
    抛出:
    
    IllegalArgumentException - if initialCapacity is less than 1
  - PriorityBlockingQueue
```
public PriorityBlockingQueue(Collection<? extends E> c)
```
    Creates a PriorityBlockingQueue containing the elements in the specified collection. If the specified collection is a SortedSet or a PriorityQueue, this priority queue will be ordered according to the same ordering. Otherwise, this priority queue will be ordered according to the Comparable of its elements.
    
    参数:
    
    c - the collection whose elements are to be placed into this priority queue
    
    抛出:
    
    ClassCastException - if elements of the specified collection cannot be compared to one another according to the priority queue's ordering
    
    NullPointerException - if the specified collection or any of its elements are null
- 方法详细资料
  - add
```
public boolean add(E e)
```
    Inserts the specified element into this priority queue.
    
    指定者:
    
    add 在接口中 BlockingQueue<E>
    
    指定者:
    
    add 在接口中 Collection<E>
    
    指定者:
    
    add 在接口中 Queue<E>
    
    覆盖:
    
    add 在类中 AbstractQueue<E>
    
    参数:
    
    e - the element to add
    
    返回:
    
    true (as specified by Collection#add)
    
    抛出:
    
    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
  - offer
```
public boolean offer(E e)
```
    Inserts the specified element into this priority queue. As the queue is unbounded, this method will never return false.
    
    指定者:
    
    offer 在接口中 BlockingQueue<E>
    
    指定者:
    
    offer 在接口中 Queue<E>
    
    参数:
    
    e - the element to add
    
    返回:
    
    true (as specified by Queue#offer)
    
    抛出:
    
    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
  - put
```
public void put(E e)
```
    Inserts the specified element into this priority queue. As the queue is unbounded, this method will never block.
    
    指定者:
    
    put 在接口中 BlockingQueue<E>
    
    参数:
    
    e - the element to add
    
    抛出:
    
    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
  - offer
```
public boolean offer(E e,
                     long timeout,
                     TimeUnit unit)
```
    Inserts the specified element into this priority queue. As the queue is unbounded, this method will never block or return false.
    
    指定者:
    
    offer 在接口中 BlockingQueue<E>
    
    参数:
    
    e - the element to add
    
    timeout - This parameter is ignored as the method never blocks
    
    unit - This parameter is ignored as the method never blocks
    
    返回:
    
    true (as specified by BlockingQueue#offer(Object,long,TimeUnit))
    
    抛出:
    
    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
  - poll
```
public E poll()
```
    从接口复制的说明: Queue
    
    Retrieves and removes the head of this queue, or returns null if this queue is empty.
    
    指定者:
    
    poll 在接口中 Queue<E>
    
    返回:
    
    the head of this queue, or null if this queue is empty
  - take
```
public E take()
       throws InterruptedException
```
    从接口复制的说明: BlockingQueue
    
    Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.
    
    指定者:
    
    take 在接口中 BlockingQueue<E>
    
    返回:
    
    the head of this queue
    
    抛出:
    
    InterruptedException - if interrupted while waiting
  - poll
```
public E poll(long timeout,
              TimeUnit unit)
       throws InterruptedException
```
    从接口复制的说明: BlockingQueue
    
    Retrieves and removes the head of this queue, waiting up to the specified wait time if necessary for an element to become available.
    
    指定者:
    
    poll 在接口中 BlockingQueue<E>
    
    参数:
    
    timeout - how long to wait before giving up, in units of unit
    
    unit - a TimeUnit determining how to interpret the timeout parameter
    
    返回:
    
    the head of this queue, or null if the specified waiting time elapses before an element is available
    
    抛出:
    
    InterruptedException - if interrupted while waiting
  - peek
```
public E peek()
```
    从接口复制的说明: Queue
    
    Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.
    
    指定者:
    
    peek 在接口中 Queue<E>
    
    返回:
    
    the head of this queue, or null if this queue is empty
  - comparator
```
public Comparator<? super E> comparator()
```
    Returns the comparator used to order the elements in this queue, or null if this queue uses the Comparable of its elements.
    
    返回:
    
    the comparator used to order the elements in this queue, or null if this queue uses the natural ordering of its elements
  - size
```
public int size()
```
    从接口复制的说明: Collection
    
    Returns the number of elements in this collection. If this collection contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.
    
    指定者:
    
    size 在接口中 Collection<E>
    
    指定者:
    
    size 在类中 AbstractCollection<E>
    
    返回:
    
    the number of elements in this collection
  - remainingCapacity
```
public int remainingCapacity()
```
    Always returns Integer.MAX_VALUE because a PriorityBlockingQueue is not capacity constrained.
    
    指定者:
    
    remainingCapacity 在接口中 BlockingQueue<E>
    
    返回:
    
    Integer.MAX_VALUE always
  - remove
```
public boolean remove(Object o)
```
    Removes a single instance of the specified element from this queue, if it is present. More formally, removes an element e such that o.equals(e), if this queue contains one or more such elements. Returns true if and only if this queue contained the specified element (or equivalently, if this queue changed as a result of the call).
    
    指定者:
    
    remove 在接口中 BlockingQueue<E>
    
    指定者:
    
    remove 在接口中 Collection<E>
    
    覆盖:
    
    remove 在类中 AbstractCollection<E>
    
    参数:
    
    o - element to be removed from this queue, if present
    
    返回:
    
    true if this queue changed as a result of the call
  - contains
```
public boolean contains(Object o)
```
    Returns true if this queue contains the specified element. More formally, returns true if and only if this queue contains at least one element e such that o.equals(e).
    
    指定者:
    
    contains 在接口中 BlockingQueue<E>
    
    指定者:
    
    contains 在接口中 Collection<E>
    
    覆盖:
    
    contains 在类中 AbstractCollection<E>
    
    参数:
    
    o - object to be checked for containment in this queue
    
    返回:
    
    true if this queue contains the specified element
  - toArray
```
public Object[] toArray()
```
    Returns an array containing all of the elements in this queue. The returned array elements are in no particular order.
    The returned array will be "safe" in that no references to it are maintained by this queue. (In other words, this method must allocate a new array). The caller is thus free to modify the returned array.
    This method acts as bridge between array-based and collection-based APIs.
    
    指定者:
    
    toArray 在接口中 Collection<E>
    
    覆盖:
    
    toArray 在类中 AbstractCollection<E>
    
    返回:
    
    an array containing all of the elements in this queue
  - toString
```
public String toString()
```
    从类复制的说明: AbstractCollection
    
    Returns a string representation of this collection. The string representation consists of a list of the collection's elements in the order they are returned by its iterator, enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", " (comma and space). Elements are converted to strings as by String#valueOf(Object).
    
    覆盖:
    
    toString 在类中 AbstractCollection<E>
    
    返回:
    
    a string representation of this collection
  - drainTo
```
public int drainTo(Collection<? super E> c)
```
    从接口复制的说明: BlockingQueue
    
    Removes all available elements from this queue and adds them to the given collection. This operation may be more efficient than repeatedly polling this queue. A failure encountered while attempting to add elements to collection c may result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain a queue to itself result in IllegalArgumentException. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress.
    
    指定者:
    
    drainTo 在接口中 BlockingQueue<E>
    
    参数:
    
    c - the collection to transfer elements into
    
    返回:
    
    the number of elements transferred
    
    抛出:
    
    UnsupportedOperationException - if addition of elements is not supported by the specified collection
    
    ClassCastException - if the class of an element of this queue prevents it from being added to the specified collection
    
    NullPointerException - if the specified collection is null
    
    IllegalArgumentException - if the specified collection is this queue, or some property of an element of this queue prevents it from being added to the specified collection
  - drainTo
```
public int drainTo(Collection<? super E> c,
                   int maxElements)
```
    从接口复制的说明: BlockingQueue
    
    Removes at most the given number of available elements from this queue and adds them to the given collection. A failure encountered while attempting to add elements to collection c may result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain a queue to itself result in IllegalArgumentException. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress.
    
    指定者:
    
    drainTo 在接口中 BlockingQueue<E>
    
    参数:
    
    c - the collection to transfer elements into
    
    maxElements - the maximum number of elements to transfer
    
    返回:
    
    the number of elements transferred
    
    抛出:
    
    UnsupportedOperationException - if addition of elements is not supported by the specified collection
    
    ClassCastException - if the class of an element of this queue prevents it from being added to the specified collection
    
    NullPointerException - if the specified collection is null
    
    IllegalArgumentException - if the specified collection is this queue, or some property of an element of this queue prevents it from being added to the specified collection
  - clear
```
public void clear()
```
    Atomically removes all of the elements from this queue. The queue will be empty after this call returns.
    
    指定者:
    
    clear 在接口中 Collection<E>
    
    覆盖:
    
    clear 在类中 AbstractQueue<E>
  - toArray
```
public <T> T[] toArray(T[] a)
```
    Returns an array containing all of the elements in this queue; the runtime type of the returned array is that of the specified array. The returned array elements are in no particular order. If the queue fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this queue.
    If this queue fits in the specified array with room to spare (i.e., the array has more elements than this queue), the element in the array immediately following the end of the queue is set to null.
    Like the toArray() method, this method acts as bridge between array-based and collection-based APIs. Further, this method allows precise control over the runtime type of the output array, and may, under certain circumstances, be used to save allocation costs.
    Suppose x is a queue known to contain only strings. The following code can be used to dump the queue into a newly allocated array of String:
```
 String[] y = x.toArray(new String[0]);
```
    Note that toArray(new Object[0]) is identical in function to toArray().
    指定者:
    
    toArray 在接口中 Collection<E>
    
    覆盖:
    
    toArray 在类中 AbstractCollection<E>
    
    类型参数:
    
    T - the runtime type of the array to contain the collection
    
    参数:
    
    a - the array into which the elements of the queue are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose
    
    返回:
    
    an array containing all of the elements in this queue
    
    抛出:
    
    ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this queue
    
    NullPointerException - if the specified array is null
  - iterator
```
public Iterator<E> iterator()
```
    Returns an iterator over the elements in this queue. The iterator does not return the elements in any particular order.
    The returned iterator is weakly consistent.
    
    指定者:
    
    iterator 在接口中 Collection<E>
    
    指定者:
    
    iterator 在接口中 Iterable<E>
    
    指定者:
    
    iterator 在类中 AbstractCollection<E>
    
    返回:
    
    an iterator over the elements in this queue
  - spliterator
```
public Spliterator<E> spliterator()
```
    Returns a Spliterator over the elements in this queue.
    The returned spliterator is weakly consistent.
    The Spliterator reports Spliterator#SIZED and Spliterator#NONNULL.
    
    指定者:
    
    spliterator 在接口中 Collection<E>
    
    指定者:
    
    spliterator 在接口中 Iterable<E>
    
    返回:
    
    a Spliterator over the elements in this queue
    
    从以下版本开始:
    
    1.8

类 PriorityBlockingQueue<E>

构造器概要

方法概要

从类继承的方法 java.util.AbstractCollection

从类继承的方法 java.util.AbstractQueue

从接口继承的方法 java.util.Collection

从接口继承的方法 java.lang.Iterable

从类继承的方法 java.lang.Object

从接口继承的方法 java.util.Queue

构造器详细资料

PriorityBlockingQueue

PriorityBlockingQueue

PriorityBlockingQueue

PriorityBlockingQueue

方法详细资料

add

offer

put

offer

poll

take

poll

peek

comparator

size

remainingCapacity

remove

contains

toArray

toString

drainTo

drainTo

clear

toArray

iterator

spliterator