org.apache.commons.collections.buffer

Class UnboundedFifoBuffer

Implemented Interfaces:
Buffer, Collection, Serializable

public class UnboundedFifoBuffer
extends AbstractCollection
implements Buffer, Serializable

UnboundedFifoBuffer is a very efficient buffer implementation. 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.

Version:
$Revision: 1.9 $ $Date: 2004/06/01 22:57:18 $
Authors:
Avalon
Federico Barbieri
Berin Loritsch
Paul Jack
Stephen Colebourne
Since:
Commons Collections 3.0 (previously in main package v2.1)

Field Summary

protected Object[]
buffer
The array of objects in the buffer.
protected int
head
The current head index.
protected int
tail
The current tail index.

Constructor Summary

UnboundedFifoBuffer()
Constructs an UnboundedFifoBuffer with the default number of elements.
UnboundedFifoBuffer(int initialSize)
Constructs an UnboundedFifoBuffer with the specified number of elements.

Method Summary

boolean
add(Object obj)
Adds the given element to this buffer.
Object
get()
Returns the next object in the buffer.
boolean
isEmpty()
Returns true if this buffer is empty; false otherwise.
Iterator
iterator()
Returns an iterator over this buffer's elements.
Object
remove()
Removes the next object from the buffer
int
size()
Returns the number of elements stored in the buffer.

Field Details

buffer

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

head

protected int head
The current head index.

tail

protected int tail
The current tail index.

Constructor Details

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

Method Details

add

public boolean add(Object obj)
Adds the given element to this buffer.
Parameters:
obj - the element to add
Returns:
true, always

get

public Object get()
Returns the next object in the buffer.
Specified by:
get in interface Buffer
Returns:
the next object in the buffer

isEmpty

public boolean isEmpty()
Returns true if this buffer is empty; false otherwise.
Returns:
true if this buffer is empty

iterator

public Iterator iterator()
Returns an iterator over this buffer's elements.
Returns:
an iterator over this buffer's elements

remove

public Object remove()
Removes the next object from the buffer
Specified by:
remove in interface Buffer
Returns:
the removed object

size

public int size()
Returns the number of elements stored in the buffer.
Returns:
this buffer's size

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