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java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractQueue<E>
java.util.concurrent.LinkedBlockingQueue<E>
public class LinkedBlockingQueue<E>
extends AbstractQueue<E>
implements BlockingQueue<E>, Serializable
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
../../../../technotes/guides/collections/index.html">
Java Collections Framework.
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Methods inherited from class java.util.AbstractCollection<E> | |
T[] toArray , add , addAll , clear , contains , containsAll , isEmpty , iterator , remove , removeAll , retainAll , size , toArray , toString |
Methods inherited from class java.lang.Object | |
clone , equals , extends Object> getClass , finalize , hashCode , notify , notifyAll , toString , wait , wait , wait |
public LinkedBlockingQueue()
Creates a LinkedBlockingQueue with a capacity ofInteger.MAX_VALUE
.
public LinkedBlockingQueue(E> c)
Creates a LinkedBlockingQueue with a capacity ofInteger.MAX_VALUE
, initially containing the elements of the given collection, added in traversal order of the collection's iterator.
- Parameters:
c
- the collection of elements to initially contain
- Throws:
NullPointerException
- if the specified collection or any of its elements are null
public LinkedBlockingQueue(int capacity)
Creates a LinkedBlockingQueue with the given (fixed) capacity.
- Parameters:
capacity
- the capacity of this queue
- Throws:
IllegalArgumentException
- if capacity is not greater than zero
publicT[] 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 thetoArray()
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().
- Specified by:
- T[] toArray in interface Collection<E>
- Overrides:
- T[] toArray in interface AbstractCollection<E>
- Parameters:
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
- Returns:
- an array containing all of the elements in this queue
- Throws:
ArrayStoreException
- 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 null
public void clear()
Atomically removes all of the elements from this queue. The queue will be empty after this call returns.
- Specified by:
- clear in interface Collection<E>
- Overrides:
- clear in interface AbstractQueue<E>
public Iteratoriterator()
Returns an iterator over the elements in this queue in proper sequence. The returned Iterator is a "weakly consistent" iterator that will never throwConcurrentModificationException
, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.
- Specified by:
- iterator in interface Collection<E>
- iterator in interface Iterable<E>
- Overrides:
- iterator in interface AbstractCollection<E>
- Returns:
- an iterator over the elements in this queue in proper sequence
public 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 methodadd
, which can fail to insert an element only by throwing an exception.
- Specified by:
- offer in interface BlockingQueue<E>
- offer in interface Queue<E>
- Throws:
NullPointerException
- if the specified element is null
public 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.
- Specified by:
- offer in interface BlockingQueue<E>
- Returns:
- true if successful, or false if the specified waiting time elapses before space is available.
- Throws:
InterruptedException
-NullPointerException
-
public E peek()
Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.
- Returns:
- the head of this queue, or null if this queue is empty
public E poll()
Retrieves and removes the head of this queue, or returns null if this queue is empty.
- Returns:
- the head of this queue, or null if this queue is empty
public E poll(long timeout, TimeUnit unit) throws InterruptedException
- Specified by:
- poll 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.
- Specified by:
- put in interface BlockingQueue<E>
- Throws:
InterruptedException
-NullPointerException
-
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.
- Specified by:
- remainingCapacity in interface BlockingQueue<E>
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 this queue contained the specified element (or equivalently, if this queue changed as a result of the call).
- Specified by:
- remove in interface BlockingQueue<E>
- remove in interface Collection<E>
- Overrides:
- remove in interface AbstractCollection<E>
- Parameters:
o
- element to be removed from this queue, if present
- Returns:
- true if this queue changed as a result of the call
public int size()
Returns the number of elements in this queue.
- Specified by:
- size in interface Collection<E>
- Overrides:
- size in interface AbstractCollection<E>
- Returns:
- the number of elements in this queue
public 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.
- Specified by:
- toArray in interface Collection<E>
- Overrides:
- toArray in interface AbstractCollection<E>
- Returns:
- an array containing all of the elements in this queue
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