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org.apache.commons.collections.buffer

Class UnboundedFifoBuffer

AbstractCollection
|
+--org.apache.commons.collections.buffer.UnboundedFifoBuffer

All Implemented Interfaces:
Buffer


public class UnboundedFifoBuffer
extends AbstractCollection
implements Buffer

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.

Since:
Commons Collections 3.0 (previously in main package v2.1)
Authors:
Avalon
Federico Barbieri
Berin Loritsch
Paul Jack
Stephen Colebourne

Field Summary

Object[]

buffer

UnboundedFifoBuffer is a very efficient buffer implementation.

int

head

int

tail

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(final 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

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.

Since:
Commons Collections 3.0 (previously in main package v2.1)
Authors:
Avalon
Federico Barbieri
Berin Loritsch
Paul Jack
Stephen Colebourne

head

protected int head


tail

protected int tail

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
Throws:
- if the size is less than 1

Method Details

add

public boolean add(final Object obj)

Adds the given element to this buffer.

Parameters:
obj - the element to add
Returns:
true, always
Throws:
- if the given element is null

get

public Object get()

Returns the next object in the buffer.

Returns:
the next object in the buffer
Throws:
BufferUnderflowException - if this buffer is empty

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

Returns:
the removed object
Throws:
BufferUnderflowException - if this buffer is empty

size

public int size()

Returns the number of elements stored in the buffer.

Returns:
this buffer's size