E - the type of elements held in this queueSerializable, Iterable<E>, Collection<E>, BlockingQueue<E>, TransferQueue<E>, Queue<E>
public class LinkedTransferQueue<E> extends AbstractQueue<E> implements TransferQueue<E>, Serializable
TransferQueue based on linked nodes. This queue orders elements FIFO (first-in-first-out) with respect to any given producer. The head of the queue is that element that has been on the queue the longest time for some producer. The tail of the queue is that element that has been on the queue the shortest time for some producer. Beware that, unlike in most collections, the size method is NOT a constant-time operation. Because of the asynchronous nature of these queues, determining the current number of elements requires a traversal of the elements, and so may report inaccurate results if this collection is modified during traversal.
Bulk operations that add, remove, or examine multiple elements, such as AbstractQueue.addAll(java.util.Collection<? extends E>), removeIf(java.util.function.Predicate<? super E>) or forEach(java.util.function.Consumer<? super E>), are not guaranteed to be performed atomically. For example, a forEach traversal concurrent with an
addAll operation might observe only some of the added elements.
This class and its iterator implement all of the optional methods of the Collection and Iterator interfaces.
Memory consistency effects: As with other concurrent collections, actions in a thread prior to placing an object into a LinkedTransferQueue happen-before actions subsequent to the access or removal of that element from the LinkedTransferQueue in another thread.
This class is a member of the Java Collections Framework.
| Constructor | Description |
|---|---|
LinkedTransferQueue() |
Creates an initially empty LinkedTransferQueue. |
LinkedTransferQueue |
Creates a LinkedTransferQueue initially containing the elements of the given collection, added in traversal order of the collection's iterator. |
| Modifier and Type | Method | Description |
|---|---|---|
boolean |
add |
Inserts the specified element at the tail of this queue. |
void |
clear() |
Removes all of the elements from this queue. |
boolean |
contains |
Returns true if this queue contains the specified element. |
int |
drainTo |
Removes all available elements from this queue and adds them to the given collection. |
int |
drainTo |
Removes at most the given number of available elements from this queue and adds them to the given collection. |
void |
forEach |
Performs the given action for each element of the Iterable until all elements have been processed or the action throws an exception. |
int |
getWaitingConsumerCount() |
Returns an estimate of the number of consumers waiting to receive elements via BlockingQueue.take() or timed poll. |
boolean |
hasWaitingConsumer() |
Returns true if there is at least one consumer waiting to receive an element via BlockingQueue.take() or timed poll. |
boolean |
isEmpty() |
Returns true if this queue contains no elements. |
Iterator |
iterator() |
Returns an iterator over the elements in this queue in proper sequence. |
boolean |
offer |
Inserts the specified element at the tail of this queue. |
boolean |
offer |
Inserts the specified element at the tail of this 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 |
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 |
Inserts the specified element at the tail of this queue. |
int |
remainingCapacity() |
Always returns Integer.MAX_VALUE because a LinkedTransferQueue is not capacity constrained. |
boolean |
remove |
Removes a single instance of the specified element from this queue, if it is present. |
boolean |
removeAll |
Removes all of this collection's elements that are also contained in the specified collection (optional operation). |
boolean |
removeIf |
Removes all of the elements of this collection that satisfy the given predicate. |
boolean |
retainAll |
Retains only the elements in this collection that are contained in the specified collection (optional operation). |
int |
size() |
Returns the number of elements in this queue. |
Spliterator |
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, in proper sequence. |
<T> T[] |
toArray |
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. |
void |
transfer |
Transfers the element to a consumer, waiting if necessary to do so. |
boolean |
tryTransfer |
Transfers the element to a waiting consumer immediately, if possible. |
boolean |
tryTransfer |
Transfers the element to a consumer if it is possible to do so before the timeout elapses. |
addAll, clear, element, remove
containsAll, toString
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
addAll, containsAll, equals, hashCode, parallelStream, stream, toArray
public LinkedTransferQueue()
LinkedTransferQueue.public LinkedTransferQueue(Collection<? extends E> c)
LinkedTransferQueue 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 Object[] toArray()
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)
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 component 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 Spliterator<E> spliterator()
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 Collection<E>
spliterator in interface Iterable<E>
Spliterator implements trySplit to permit limited parallelism.Spliterator over the elements in this queuepublic void put(E e)
put in interface BlockingQueue<E>
e - the element to addNullPointerException - if the specified element is nullpublic boolean offer(E e, long timeout, TimeUnit unit)
false.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 (as specified by BlockingQueue.offer)NullPointerException - if the specified element is nullpublic boolean offer(E e)
false.offer in interface BlockingQueue<E>
offer in interface Queue<E>
e - the element to addtrue (as specified by Queue.offer(E))NullPointerException - if the specified element is nullpublic boolean add(E e)
IllegalStateException or return false.add in interface BlockingQueue<E>
add in interface Collection<E>
add in interface Queue<E>
add in class AbstractQueue<E>
e - the element to addtrue (as specified by Collection.add(E))NullPointerException - if the specified element is nullpublic boolean tryTransfer(E e)
More precisely, transfers the specified element immediately if there exists a consumer already waiting to receive it (in take() or timed poll), otherwise returning false without enqueuing the element.
tryTransfer in interface TransferQueue<E>
e - the element to transfertrue if the element was transferred, else false
NullPointerException - if the specified element is nullpublic void transfer(E e) throws InterruptedException
More precisely, transfers the specified element immediately if there exists a consumer already waiting to receive it (in take() or timed poll), else inserts the specified element at the tail of this queue and waits until the element is received by a consumer.
transfer in interface TransferQueue<E>
e - the element to transferNullPointerException - if the specified element is nullInterruptedException - if interrupted while waiting, in which case the element is not left enqueuedpublic boolean tryTransfer(E e, long timeout, TimeUnit unit) throws InterruptedException
More precisely, transfers the specified element immediately if there exists a consumer already waiting to receive it (in take() or timed poll), else inserts the specified element at the tail of this queue and waits until the element is received by a consumer, returning false if the specified wait time elapses before the element can be transferred.
tryTransfer in interface TransferQueue<E>
e - the element to transfertimeout - 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 completion, in which case the element is not left enqueuedNullPointerException - if the specified element is nullInterruptedException - if interrupted while waiting, in which case the element is not left enqueuedpublic E take() throws InterruptedException
BlockingQueuetake in interface BlockingQueue<E>
InterruptedException - if interrupted while waitingpublic E poll(long timeout, TimeUnit unit) throws InterruptedException
BlockingQueuepoll 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()
Queuenull if this queue is empty.public int drainTo(Collection<? super E> c)
BlockingQueuec 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 intoNullPointerException - 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)
BlockingQueuec 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 transferNullPointerException - 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()
The returned iterator is weakly consistent.
iterator in interface Collection<E>
iterator in interface Iterable<E>
iterator in class AbstractCollection<E>
public E peek()
Queuenull if this queue is empty.public boolean isEmpty()
true if this queue contains no elements.isEmpty in interface Collection<E>
isEmpty in class AbstractCollection<E>
true if this queue contains no elementspublic boolean hasWaitingConsumer()
TransferQueuetrue if there is at least one consumer waiting to receive an element via BlockingQueue.take() or timed poll. The return value represents a momentary state of affairs.hasWaitingConsumer in interface TransferQueue<E>
true if there is at least one waiting consumerpublic int size()
Integer.MAX_VALUE elements, returns Integer.MAX_VALUE. Beware that, unlike in most collections, this method is NOT a constant-time operation. Because of the asynchronous nature of these queues, determining the current number of elements requires an O(n) traversal.
size in interface Collection<E>
public int getWaitingConsumerCount()
TransferQueueBlockingQueue.take() or timed poll. The return value is an approximation of a momentary state of affairs, that may be inaccurate if consumers have completed or given up waiting. The value may be useful for monitoring and heuristics, but not for synchronization control. Implementations of this method are likely to be noticeably slower than those for TransferQueue.hasWaitingConsumer().getWaitingConsumerCount in interface TransferQueue<E>
public boolean remove(Object o)
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 BlockingQueue<E>
remove in interface Collection<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)
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 BlockingQueue<E>
contains in interface Collection<E>
contains in class AbstractCollection<E>
o - object to be checked for containment in this queuetrue if this queue contains the specified elementpublic int remainingCapacity()
Integer.MAX_VALUE because a LinkedTransferQueue is not capacity constrained.remainingCapacity in interface BlockingQueue<E>
Integer.MAX_VALUE (as specified by BlockingQueue.remainingCapacity())public boolean removeIf(Predicate<? super E> filter)
CollectionremoveIf in interface Collection<E>
filter - a predicate which returns true for elements to be removedtrue if any elements were removedNullPointerException - if the specified filter is nullpublic boolean removeAll(Collection<?> c)
AbstractCollectionremoveAll in interface Collection<E>
removeAll in class AbstractCollection<E>
c - collection containing elements to be removed from this collectiontrue if this collection changed as a result of the callNullPointerException - if this collection contains one or more null elements and the specified collection does not support null elements (optional) or if the specified collection is nullpublic boolean retainAll(Collection<?> c)
AbstractCollectionretainAll in interface Collection<E>
retainAll in class AbstractCollection<E>
c - collection containing elements to be retained in this collectiontrue if this collection changed as a result of the callNullPointerException - if this collection contains one or more null elements and the specified collection does not permit null elements (optional) or if the specified collection is nullpublic void clear()
AbstractQueueThis implementation repeatedly invokes poll until it returns null.
clear in interface Collection<E>
clear in class AbstractQueue<E>
public void forEach(Consumer<? super E> action)
IterableIterable until all elements have been processed or the action throws an exception. Actions are performed in the order of iteration, if that order is specified. Exceptions thrown by the action are relayed to the caller. The behavior of this method is unspecified if the action performs side-effects that modify the underlying source of elements, unless an overriding class has specified a concurrent modification policy.
forEach in interface Iterable<E>
action - The action to be performed for each elementNullPointerException - if the specified action is null
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/concurrent/LinkedTransferQueue.html