org.apache.commons.collections
Class BoundedFifoBuffer

java.lang.Object
  |
  +--java.util.AbstractCollection
        |
        +--org.apache.commons.collections.BoundedFifoBuffer

All Implemented Interfaces:

Buffer, Collection

public class BoundedFifoBuffer

extends AbstractCollection

implements Buffer

The BoundedFifoBuffer is a very efficient implementation of Buffer that does not alter the size of the buffer at runtime.

The removal order of a BoundedFifoBuffer 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), remove() and 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 BoundedFifoBuffer:

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

This buffer prevents null objects from being added.

Since:

2.1

Version:

$Id: BoundedFifoBuffer.java,v 1.5 2002/10/13 12:59:04 scolebourne Exp $

Author:

Avalon, Berin Loritsch, Paul Jack, Stephen Colebourne

Constructor Summary

BoundedFifoBuffer()
Constructs a new BoundedFifoBuffer big enough to hold 32 elements.

BoundedFifoBuffer(Collection coll)
Constructs a new BoundedFifoBuffer big enough to hold all of the elements in the specified collection.

BoundedFifoBuffer(int size)
Constructs a new BoundedFifoBuffer big enough to hold the specified number of elements.

Method Summary

boolean	add(Object element) Adds the given element to this buffer.
void	clear() Clears this buffer.
Object	get() Returns the least recently inserted element in this 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 least recently inserted element from this buffer.
int	size() Returns the number of elements stored in the buffer.

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

BoundedFifoBuffer

public BoundedFifoBuffer()

Constructs a new BoundedFifoBuffer big enough to hold 32 elements.

BoundedFifoBuffer

public BoundedFifoBuffer(Collection coll)

Constructs a new BoundedFifoBuffer big enough to hold all of the elements in the specified collection. That collection's elements will also be added to the buffer.

Parameters:

coll - the collection whose elements to add

BoundedFifoBuffer

public BoundedFifoBuffer(int size)

Constructs a new BoundedFifoBuffer big enough to hold the specified number of elements.

Parameters:

size - the maximum number of elements for this fifo

Throws:

IllegalArgumentException - if the size is less than 1

Method Detail

add

public boolean add(Object element)

Adds the given element to this buffer.

Specified by:

add in interface Collection

Overrides:

add in class AbstractCollection

Parameters:

element - the element to add

Returns:

true, always

Throws:

NullPointerException - if the given element is null

BufferOverflowException - if this buffer is full

clear

public void clear()

Clears this buffer.

Specified by:

clear in interface Collection

Overrides:

clear in class AbstractCollection

get

public Object get()

Returns the least recently inserted element in this buffer.

Specified by:

get in interface Buffer

Returns:

the least recently inserted element

Throws:

BufferUnderflowException - if the buffer is empty

isEmpty

public boolean isEmpty()

Returns true if this buffer is empty; false otherwise.

Specified by:

isEmpty in interface Collection

Overrides:

isEmpty in class AbstractCollection

Returns:

true if this buffer is empty

iterator

public Iterator iterator()

Returns an iterator over this buffer's elements.

Specified by:

iterator in interface Collection

Specified by:

iterator in class AbstractCollection

Returns:

an iterator over this buffer's elements

remove

public Object remove()

Removes the least recently inserted element from this buffer.

Specified by:

remove in interface Buffer

Returns:

the least recently inserted element

Throws:

BufferUnderflowException - if the buffer is empty

size

public int size()

Returns the number of elements stored in the buffer.

Specified by:

size in interface Collection

Specified by:

size in class AbstractCollection

Returns:

this buffer's size