org.apache.commons.collections.buffer
Class CircularFifoBuffer

java.lang.Object
  java.util.AbstractCollection
      org.apache.commons.collections.buffer.BoundedFifoBuffer
          org.apache.commons.collections.buffer.CircularFifoBuffer

All Implemented Interfaces:

java.io.Serializable, java.lang.Iterable, java.util.Collection, BoundedCollection, Buffer

public class CircularFifoBuffer
extends BoundedFifoBuffer

CircularFifoBuffer is a first in first out buffer with a fixed size that replaces its oldest element if full.

The removal order of a CircularFifoBuffer 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 add(Object), BoundedFifoBuffer.remove() and BoundedFifoBuffer.get() operations all perform in 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 CircularFifoBuffer:

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

This buffer prevents null objects from being added.

This class is Serializable from Commons Collections 3.1.

Since:

Commons Collections 3.0

Version:

$Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $

Author:

Stefano Fornari, Stephen Colebourne

See Also:

Serialized Form

Constructor Summary

CircularFifoBuffer()
Constructor that creates a buffer with the default size of 32.

CircularFifoBuffer(java.util.Collection coll)
Constructor that creates a buffer from the specified collection.

CircularFifoBuffer(int size)
Constructor that creates a buffer with the specified size.

Method Summary

boolean

add(java.lang.Object element) If the buffer is full, the least recently added element is discarded so that a new element can be inserted.

Methods inherited from class org.apache.commons.collections.buffer.BoundedFifoBuffer

clear, get, isEmpty, isFull, iterator, maxSize, remove, size

Methods inherited from class java.util.AbstractCollection

addAll, contains, containsAll, remove, removeAll, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

addAll, contains, containsAll, equals, hashCode, remove, removeAll, retainAll, toArray, toArray

Methods inherited from interface java.util.Collection

addAll, contains, containsAll, equals, hashCode, remove, removeAll, retainAll, toArray, toArray

Constructor Detail

CircularFifoBuffer

public CircularFifoBuffer()

Constructor that creates a buffer with the default size of 32.

CircularFifoBuffer

public CircularFifoBuffer(int size)

Constructor that creates a buffer with the specified size.

Parameters:

size - the size of the buffer (cannot be changed)

Throws:

java.lang.IllegalArgumentException - if the size is less than 1

CircularFifoBuffer

public CircularFifoBuffer(java.util.Collection coll)

Constructor that creates a buffer from the specified collection. The collection size also sets the buffer size

Parameters:

coll - the collection to copy into the buffer, may not be null

Throws:

java.lang.NullPointerException - if the collection is null

Method Detail

add

public boolean add(java.lang.Object element)

If the buffer is full, the least recently added element is discarded so that a new element can be inserted.

Specified by:

add in interface java.util.Collection

Overrides:

add in class BoundedFifoBuffer

Parameters:

element - the element to add

Returns:

true, always