E - the type of elements held in this collectionpublic class SynchronousQueue<E> extends AbstractQueue<E> implements BlockingQueue<E>, Serializable
Synchronous queues are similar to rendezvous channels used in CSP and Ada. They are well suited for handoff designs, in which an object running in one thread must sync up with an object running in another thread in order to hand it some information, event, or task.
This class supports an optional fairness policy for ordering waiting producer and consumer threads. By default, this ordering is not guaranteed. However, a queue constructed with fairness set to true grants threads access in FIFO order.
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.
| Constructor and Description |
|---|
SynchronousQueue()
Creates a SynchronousQueue with nonfair access policy.
|
SynchronousQueue(boolean fair)
Creates a SynchronousQueue with the specified fairness policy.
|
| Modifier and Type | Method and Description |
|---|---|
void |
clear()
Does nothing.
|
boolean |
contains(Object o)
Always returns false.
|
boolean |
containsAll(Collection<?> c)
Returns false unless the given collection is empty.
|
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.
|
boolean |
isEmpty()
Always returns true.
|
Iterator<E> |
iterator()
Returns an empty iterator in which hasNext always returns
false.
|
boolean |
offer(E e)
Inserts the specified element into this queue, if another thread is
waiting to receive it.
|
boolean |
offer(E o,
long timeout,
TimeUnit unit)
Inserts the specified element into this queue, waiting if necessary
up to the specified wait time for another thread to receive it.
|
E |
peek()
Always returns null.
|
E |
poll()
Retrieves and removes the head of this queue, if another thread
is currently making an element available.
|
E |
poll(long timeout,
TimeUnit unit)
Retrieves and removes the head of this queue, waiting
if necessary up to the specified wait time, for another thread
to insert it.
|
void |
put(E o)
Adds the specified element to this queue, waiting if necessary for
another thread to receive it.
|
int |
remainingCapacity()
Always returns zero.
|
boolean |
remove(Object o)
Always returns false.
|
boolean |
removeAll(Collection<?> c)
Always returns false.
|
boolean |
retainAll(Collection<?> c)
Always returns false.
|
int |
size()
Always returns zero.
|
E |
take()
Retrieves and removes the head of this queue, waiting if necessary
for another thread to insert it.
|
Object[] |
toArray()
Returns a zero-length array.
|
<T> T[] |
toArray(T[] a)
Sets the zeroeth element of the specified array to null
(if the array has non-zero length) and returns it.
|
add, addAll, element, removetoStringclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitaddaddAll, equals, hashCodepublic SynchronousQueue()
public SynchronousQueue(boolean fair)
fair - if true, waiting threads contend in FIFO order for
access; otherwise the order is unspecified.public void put(E o) throws InterruptedException
put in interface BlockingQueue<E>o - the element to addInterruptedException - if interrupted while waitingNullPointerException - if the specified element is nullpublic boolean offer(E o, long timeout, TimeUnit unit) throws InterruptedException
offer in interface BlockingQueue<E>o - the element to addtimeout - how long to wait before giving up, in units of
unitunit - a TimeUnit determining how to interpret the
timeout parameterInterruptedException - if interrupted while waitingNullPointerException - if the specified element is nullpublic boolean offer(E e)
offer in interface BlockingQueue<E>offer in interface Queue<E>e - the element to addNullPointerException - if the specified element is nullpublic E take() throws InterruptedException
take in interface BlockingQueue<E>InterruptedException - if interrupted while waitingpublic E poll(long timeout, TimeUnit unit) throws InterruptedException
poll in interface BlockingQueue<E>timeout - how long to wait before giving up, in units of
unitunit - a TimeUnit determining how to interpret the
timeout parameterInterruptedException - if interrupted while waitingpublic E poll()
public boolean isEmpty()
isEmpty in interface Collection<E>isEmpty in class AbstractCollection<E>public int size()
size in interface Collection<E>size in class AbstractCollection<E>public int remainingCapacity()
remainingCapacity in interface BlockingQueue<E>public void clear()
clear in interface Collection<E>clear in class AbstractQueue<E>public boolean contains(Object o)
contains in interface Collection<E>contains in interface BlockingQueue<E>contains in class AbstractCollection<E>o - the elementpublic boolean remove(Object o)
remove in interface Collection<E>remove in interface BlockingQueue<E>remove in class AbstractCollection<E>o - the element to removepublic boolean containsAll(Collection<?> c)
containsAll in interface Collection<E>containsAll in class AbstractCollection<E>c - the collectionAbstractCollection.contains(Object)public boolean removeAll(Collection<?> c)
removeAll in interface Collection<E>removeAll in class AbstractCollection<E>c - the collectionAbstractCollection.remove(Object),
AbstractCollection.contains(Object)public boolean retainAll(Collection<?> c)
retainAll in interface Collection<E>retainAll in class AbstractCollection<E>c - the collectionAbstractCollection.remove(Object),
AbstractCollection.contains(Object)public E peek()
public Iterator<E> iterator()
iterator in interface Iterable<E>iterator in interface Collection<E>iterator in class AbstractCollection<E>public Object[] toArray()
toArray in interface Collection<E>toArray in class AbstractCollection<E>public <T> T[] toArray(T[] a)
toArray in interface Collection<E>toArray in class AbstractCollection<E>a - the arrayNullPointerException - if the specified array is nullpublic int drainTo(Collection<? super E> c)
BlockingQueuedrainTo 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)
BlockingQueuedrainTo 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 collection Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2020, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.