Package com.google.common.collect

Class EvictingQueue<E>

  • All Implemented Interfaces:
    Iterable<E>, Collection<E>, Queue<E>
    @Beta
@GwtIncompatible("java.util.ArrayDeque")
public final class EvictingQueue<E>
extends ForwardingQueue<E>
    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.

    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

    • 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.

      • 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 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 Collection<E>
        Specified by:
        add in interface Queue<E>
        Overrides:
        add in class ForwardingCollection<E>
        Returns:
        true always