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## 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:
  BoundedCollection, Buffer, Collection, Serializable

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: 1.5 $ $Date: 2004/06/03 22:02:13 $
Author:
  Stefano Fornari, Stephen Colebourne
See Also:
  Serialized Form

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

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:
  `IllegalArgumentException` - if the size is less than 1

### CircularFifoBuffer

    public CircularFifoBuffer(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:
  `NullPointerException` - if the collection is null

Method Detail

### add

    public boolean add(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 `Collection`
  Overrides:
    `add` in class `BoundedFifoBuffer`
  Parameters:
    `element` - the element to add
  Returns:
    true, always

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Copyright © 2001-2004 Apache Software Foundation. All Rights Reserved.