Package org.apache.commons.collections.buffer

Class UnboundedFifoBuffer

  • All Implemented Interfaces:
    Serializable, Iterable, Collection, Buffer
    public class UnboundedFifoBuffer
extends AbstractCollection
implements Buffer, Serializable
    UnboundedFifoBuffer is a very efficient implementation of Buffer that can grow to any size. According to performance testing, it exhibits a constant access time, but it also outperforms ArrayList when used for the same purpose.

    The removal order of an UnboundedFifoBuffer is based on the insertion order; elements are removed in the same order in which they were added. The iteration order is the same as the removal order.

    The remove() and get() operations perform in constant time. The add(Object) operation performs in amortized constant time. All other operations perform in linear time or worse.

    Note that this implementation is not synchronized. The following can be used to provide synchronized access to your UnboundedFifoBuffer: 

       Buffer fifo = BufferUtils.synchronizedBuffer(new UnboundedFifoBuffer());

    This buffer prevents null objects from being added.

    This class is Serializable from Commons Collections 3.1.

    Since:
    Commons Collections 3.0 (previously in main package v2.1)
    Version:
    $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
    Author:
    Avalon, Federico Barbieri, Berin Loritsch, Paul Jack, Stephen Colebourne, Andreas Schlosser, Thomas Knych, Jordan Krey
    See Also:
    Serialized Form

    • Field Detail

      • buffer

        protected transient Object[] buffer
        The array of objects in the buffer.

      • head

        protected transient int head
        The current head index.

      • tail

        protected transient int tail
        The current tail index.

    • Constructor Detail

      • UnboundedFifoBuffer

        public UnboundedFifoBuffer()
        Constructs an UnboundedFifoBuffer with the default number of elements. It is exactly the same as performing the following: 
           new UnboundedFifoBuffer(32);

      • UnboundedFifoBuffer

        public UnboundedFifoBuffer​(int initialSize)
        Constructs an UnboundedFifoBuffer with the specified number of elements. The integer must be a positive integer.
        Parameters:
        initialSize - the initial size of the buffer
        Throws:
        IllegalArgumentException - if the size is less than 1