Package com.google.common.collect

Class EvictingQueue<E>

java.lang.Object

com.google.common.collect.ForwardingObject

com.google.common.collect.ForwardingCollection<E>

com.google.common.collect.ForwardingQueue<E>

com.google.common.collect.EvictingQueue<E>

All Implemented Interfaces:

java.io.Serializable, java.lang.Iterable<E>, java.util.Collection<E>, java.util.Queue<E>

@Beta
@GwtCompatible
public final class EvictingQueue<E>
extends ForwardingQueue<E>
implements java.io.Serializable

A non-blocking queue which automatically evicts elements from the head of the queue when attempting to add new elements onto the queue and it is full. This data structure is logically equivalent to a circular buffer (i.e., cyclic buffer or ring buffer).

An evicting queue must be configured with a maximum size. Each time an element is added to a full queue, the queue automatically removes its head element. This is different from conventional bounded queues, which either block or reject new elements when full.

This class is not thread-safe, and does not accept null elements.

Since:

15.0

See Also:

Serialized Form

Method Summary

Modifier and Type	Method	Description
boolean	add(E e)	Adds the given element to this queue.
boolean	addAll(java.util.Collection<? extends E> collection)
boolean	contains(java.lang.Object object)
static <E> EvictingQueue<E>	create(int maxSize)	Creates and returns a new evicting queue that will hold up to maxSize elements.
protected java.util.Queue<E>	delegate()	Returns the backing delegate instance that methods are forwarded to.
boolean	offer(E e)	Adds the given element to this queue.
int	remainingCapacity()	Returns the number of additional elements that this queue can accept without evicting; zero if the queue is currently full.
boolean	remove(java.lang.Object object)

Methods inherited from interface java.util.Collection

clear, containsAll, equals, hashCode, isEmpty, iterator, parallelStream, removeAll, removeIf, retainAll, size, spliterator, stream, toArray, toArray

Methods inherited from class com.google.common.collect.ForwardingCollection

clear, containsAll, isEmpty, iterator, removeAll, retainAll, size, standardAddAll, standardClear, standardContains, standardContainsAll, standardIsEmpty, standardRemove, standardRemoveAll, standardRetainAll, standardToArray, standardToArray, standardToString, toArray, toArray

Methods inherited from class com.google.common.collect.ForwardingObject

toString

Methods inherited from class com.google.common.collect.ForwardingQueue

element, peek, poll, remove, standardOffer, standardPeek, standardPoll

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

create

public static <E> EvictingQueue<E> create(int maxSize)

Creates and returns a new evicting queue that will hold up to maxSize elements.

When maxSize is zero, elements will be evicted immediately after being added to the queue.

remainingCapacity

public int remainingCapacity()

Returns the number of additional elements that this queue can accept without evicting; zero if the queue is currently full.

Since:

16.0

delegate

protected java.util.Queue<E> delegate()

Description copied from class: ForwardingObject

Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such as ForwardingSet.delegate(). Concrete subclasses override this method to supply the instance being decorated.

Specified by:

delegate in class ForwardingQueue<E>

offer

public boolean offer(E e)

Adds the given element to this queue. If the queue is currently full, the element at the head of the queue is evicted to make room.

Specified by:

offer in interface java.util.Queue<E>

Overrides:

offer in class ForwardingQueue<E>

Returns:

true always

add

public boolean add(E e)

Adds the given element to this queue. If the queue is currently full, the element at the head of the queue is evicted to make room.

Specified by:

add in interface java.util.Collection<E>

Specified by:

add in interface java.util.Queue<E>

Overrides:

add in class ForwardingCollection<E>

Returns:

true always

addAll

public boolean addAll(java.util.Collection<? extends E> collection)

Specified by:

addAll in interface java.util.Collection<E>

Overrides:

addAll in class ForwardingCollection<E>

contains

public boolean contains(java.lang.Object object)

Specified by:

contains in interface java.util.Collection<E>

Overrides:

contains in class ForwardingCollection<E>

remove

public boolean remove(java.lang.Object object)

Specified by:

remove in interface java.util.Collection<E>

Overrides:

remove in class ForwardingCollection<E>