E - the type of elements held in this collectionpublic class LinkedBlockingQueue<E> extends AbstractQueue<E> implements BlockingQueue<E>, Serializable
An optionally-bounded blocking queue based on linked nodes. This queue orders elements FIFO (first-in-first-out). The head of the queue is that element that has been on the queue the longest time. The tail of the queue is that element that has been on the queue the shortest time. New elements are inserted at the tail of the queue, and the queue retrieval operations obtain elements at the head of the queue. Linked queues typically have higher throughput than array-based queues but less predictable performance in most concurrent applications.
The optional capacity bound constructor argument serves as a way to prevent excessive queue expansion. The capacity, if unspecified, is equal to Integer.MAX_VALUE. Linked nodes are dynamically created upon each insertion unless this would bring the queue above capacity.
This class and its iterator implement all of the optional methods of the Collection and Iterator interfaces.
This class is a member of the Java Collections Framework.
public LinkedBlockingQueue()
Creates a LinkedBlockingQueue with a capacity of Integer.MAX_VALUE.
public LinkedBlockingQueue(int capacity)
Creates a LinkedBlockingQueue with the given (fixed) capacity.
capacity - the capacity of this queueIllegalArgumentException - if capacity is not greater than zeropublic LinkedBlockingQueue(Collection<? extends E> c)
Creates a LinkedBlockingQueue with a capacity of Integer.MAX_VALUE, initially containing the elements of the given collection, added in traversal order of the collection's iterator.
c - the collection of elements to initially containNullPointerException - if the specified collection or any of its elements are nullpublic int size()
Returns the number of elements in this queue.
size in interface Collection<E>
size in class AbstractCollection<E>
public int remainingCapacity()
Returns the number of additional elements that this queue can ideally (in the absence of memory or resource constraints) accept without blocking. This is always equal to the initial capacity of this queue less the current size of this queue.
Note that you cannot always tell if an attempt to insert an element will succeed by inspecting remainingCapacity because it may be the case that another thread is about to insert or remove an element.
remainingCapacity in interface BlockingQueue<E>
public void put(E e)
throws InterruptedException Inserts the specified element at the tail of this queue, waiting if necessary for space to become available.
put in interface BlockingQueue<E>
e - the element to addInterruptedException - if interrupted while waitingNullPointerException - if the specified element is nullpublic boolean offer(E e,
long timeout,
TimeUnit unit)
throws InterruptedException Inserts the specified element at the tail of this queue, waiting if necessary up to the specified wait time for space to become available.
offer in interface BlockingQueue<E>
e - the element to addtimeout - how long to wait before giving up, in units of unit
unit - a TimeUnit determining how to interpret the timeout parametertrue if successful, or false if the specified waiting time elapses before space is availableInterruptedException - if interrupted while waitingNullPointerException - if the specified element is nullpublic boolean offer(E e)
Inserts the specified element at the tail of this queue if it is possible to do so immediately without exceeding the queue's capacity, returning true upon success and false if this queue is full. When using a capacity-restricted queue, this method is generally preferable to method add, which can fail to insert an element only by throwing an exception.
offer in interface BlockingQueue<E>
offer in interface Queue<E>
e - the element to addtrue if the element was added to this queue, else false
NullPointerException - if the specified element is nullpublic E take()
throws InterruptedException Description copied from interface: BlockingQueue
Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.
take in interface BlockingQueue<E>
InterruptedException - if interrupted while waitingpublic E poll(long timeout,
TimeUnit unit)
throws InterruptedException Description copied from interface: BlockingQueue
Retrieves and removes the head of this queue, waiting up to the specified wait time if necessary for an element to become available.
poll in interface BlockingQueue<E>
timeout - how long to wait before giving up, in units of unit
unit - a TimeUnit determining how to interpret the timeout parameternull if the specified waiting time elapses before an element is availableInterruptedException - if interrupted while waitingpublic E poll()
Description copied from interface: Queue
Retrieves and removes the head of this queue, or returns null if this queue is empty.
poll in interface Queue<E>
null if this queue is emptypublic E peek()
Description copied from interface: Queue
Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.
peek in interface Queue<E>
null if this queue is emptypublic 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 this queue contained the specified element (or equivalently, if this queue changed as a result of the call).
remove in interface Collection<E>
remove in interface BlockingQueue<E>
remove in class AbstractCollection<E>
o - element to be removed from this queue, if presenttrue if this queue changed as a result of the callpublic 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).
contains in interface Collection<E>
contains in interface BlockingQueue<E>
contains in class AbstractCollection<E>
o - object to be checked for containment in this queuetrue if this queue contains the specified elementpublic Object[] toArray()
Returns an array containing all of the elements in this queue, in proper sequence.
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.
toArray in interface Collection<E>
toArray in class AbstractCollection<E>
public <T> T[] toArray(T[] a)
Returns an array containing all of the elements in this queue, in proper sequence; the runtime type of the returned array is that of the specified array. 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().toArray in interface Collection<E>
toArray in class AbstractCollection<E>
T - the runtime type of the array to contain the collectiona - 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 purposeArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this queueNullPointerException - if the specified array is nullpublic String toString()
Description copied from class: 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).
toString in class AbstractCollection<E>
public void clear()
Atomically removes all of the elements from this queue. The queue will be empty after this call returns.
clear in interface Collection<E>
clear in class AbstractQueue<E>
public int drainTo(Collection<? super E> c)
Description copied from interface: 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.
drainTo in interface BlockingQueue<E>
c - the collection to transfer elements intoUnsupportedOperationException - if addition of elements is not supported by the specified collectionClassCastException - if the class of an element of this queue prevents it from being added to the specified collectionNullPointerException - if the specified collection is nullIllegalArgumentException - if the specified collection is this queue, or some property of an element of this queue prevents it from being added to the specified collectionpublic int drainTo(Collection<? super E> c,
int maxElements) Description copied from interface: 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.
drainTo in interface BlockingQueue<E>
c - the collection to transfer elements intomaxElements - the maximum number of elements to transferUnsupportedOperationException - if addition of elements is not supported by the specified collectionClassCastException - if the class of an element of this queue prevents it from being added to the specified collectionNullPointerException - if the specified collection is nullIllegalArgumentException - if the specified collection is this queue, or some property of an element of this queue prevents it from being added to the specified collectionpublic Iterator<E> iterator()
Returns an iterator over the elements in this queue in proper sequence. The elements will be returned in order from first (head) to last (tail).
The returned iterator is weakly consistent.
iterator in interface Iterable<E>
iterator in interface Collection<E>
iterator in class AbstractCollection<E>
public Spliterator<E> spliterator()
Returns a Spliterator over the elements in this queue.
The returned spliterator is weakly consistent.
The Spliterator reports Spliterator.CONCURRENT, Spliterator.ORDERED, and Spliterator.NONNULL.
spliterator in interface Iterable<E>
spliterator in interface Collection<E>
Spliterator implements trySplit to permit limited parallelism.Spliterator over the elements in this queue
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