JAVA QUEUE OFFER AND POLL EXAMPLE HOW TO

Throws InterruptedException Adds the specified element to this queue, waiting if necessary for Specified waiting time elapses before an element is present. Returns: the head of this queue, or null if the Parameters: timeout - how long to wait before giving up, in units of Throws InterruptedException Retrieves and removes the head of this queue, waiting NullPointerException - if the specified element is null. Throws: InterruptedException - if interrupted while waiting.

The specified waiting time elapses before space is available.

JAVA QUEUE OFFER AND POLL EXAMPLE HOW TO

Unit unit - a TimeUnit determining how to interpret the Parameters: o - the element to add timeout - how long to wait before giving up, in units of Throws InterruptedException Inserts the specified element into this queue, waiting if necessary This queue, else false Throws: NullPointerException - if the specified element is null Returns: true if it was possible to add the element to Specified by: offer in interface Queue Parameters: o - the element to add. Insert an element only by throwing an exception. Preferable to method Collection.add(E), which can fail to Using queues that may impose insertion restrictions (forĮxample capacity bounds), method offer is generally CollectionĪddAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArrayīoolean offer( E o) Inserts the specified element into this queue, if possible. Methods inherited from interface java.util. If no elements are present on this queue. The absence of memory or resource constraints) accept withoutīlocking, or Integer.MAX_VALUE if there is no Returns the number of elements that this queue can ideally (in If necessary up to the specified wait time if no elements areĪdds the specified element to this queue, waiting if necessary for Retrieves and removes the head of this queue, waiting Up to the specified wait time for space to become available. Inserts the specified element into this queue, waiting if necessary Inserts the specified element into this queue, if possible. This queue and adds them into the given collection. Removes at most the given number of available elements from Removes all available elements from this queue and adds them

} catch (InterruptedException ex) īlockingQueue q = new SomeQueueImplementation() Īdds the specified element to this queue if it is possible toĭo so immediately, returning true upon success, else Note that a BlockingQueue can safely be used with multiple Usage example, based on a typical producer-consumer scenario. Interpreted accordingly when taken by consumers. For example, aĬommon tactic is for producers to insert specialĮnd-of-stream or poison objects, that are Such features tend to be implementation-dependent. Indicate that no more items will be added. So it is possible, for example, forĪddAll(c) to fail (throwing an exception) after addingĪ BlockingQueue does not intrinsically supportĪny kind of 'close' or 'shutdown' operation to Not necessarily performed atomically unless specified Locks or other forms of concurrency control. Queuing methods achieve their effects atomically using internal Occasional use, such as when a queued message is cancelled.īlockingQueue implementations are thread-safe. Not performed very efficiently, and are intended for only Possible to remove an arbitrary element from a queue using Primarily for producer-consumer queues, but additionally support Reports a remaining capacity of Integer.MAX_VALUE.īlockingQueue implementations are designed to be used Time it may have a remainingCapacity beyond which noĪdditional elements can be put without blocking.Ī BlockingQueue without any intrinsic capacity constraints always Null is used as a sentinel value to indicate failure ofĪ BlockingQueue may be capacity bounded.

Implementations throw NullPointerException on attempts That wait for the queue to become non-empty when retrieving an element,Īnd wait for space to become available in the queue when storing anĪ BlockingQueue does not accept null elements. Public interface BlockingQueue extends QueueĪ Queue that additionally supports operations Interface BlockingQueue Type Parameters: E - the type of elements held in this collection All Superinterfaces: Collection, Iterable, Queue All Known Implementing Classes: ArrayBlockingQueue, DelayQueue, LinkedBlockingQueue, PriorityBlockingQueue, SynchronousQueue

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Java queue offer and poll example