org.apache.commons.collections
Class BoundedFifoBuffer

java.lang.Object
  |
  +--java.util.AbstractCollection
        |
        +--org.apache.commons.collections.BoundedFifoBuffer
All Implemented Interfaces:
Buffer, java.util.Collection

public class BoundedFifoBuffer
extends java.util.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 1.5.2.1 2004/05/22 12:14:02 scolebourne Exp $
Author:
Avalon, Berin Loritsch, Paul Jack, Stephen Colebourne

Constructor Summary
BoundedFifoBuffer()
          Constructs a new BoundedFifoBuffer big enough to hold 32 elements.
BoundedFifoBuffer(java.util.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(java.lang.Object element)
          Adds the given element to this buffer.
 void clear()
          Clears this buffer.
 java.lang.Object get()
          Returns the least recently inserted element in this buffer.
 boolean isEmpty()
          Returns true if this buffer is empty; false otherwise.
 java.util.Iterator iterator()
          Returns an iterator over this buffer's elements.
 java.lang.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
equals, 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(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:
java.lang.IllegalArgumentException - if the size is less than 1

BoundedFifoBuffer

public BoundedFifoBuffer(java.util.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
Method Detail

size

public int size()
Returns the number of elements stored in the buffer.

Specified by:
size in interface java.util.Collection
Specified by:
size in class java.util.AbstractCollection
Returns:
this buffer's size

isEmpty

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

Specified by:
isEmpty in interface java.util.Collection
Overrides:
isEmpty in class java.util.AbstractCollection
Returns:
true if this buffer is empty

clear

public void clear()
Clears this buffer.

Specified by:
clear in interface java.util.Collection
Overrides:
clear in class java.util.AbstractCollection

add

public boolean add(java.lang.Object element)
Adds the given element to this buffer.

Specified by:
add in interface java.util.Collection
Overrides:
add in class java.util.AbstractCollection
Parameters:
element - the element to add
Returns:
true, always
Throws:
java.lang.NullPointerException - if the given element is null
BufferOverflowException - if this buffer is full

get

public java.lang.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

remove

public java.lang.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

iterator

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

Specified by:
iterator in interface java.util.Collection
Specified by:
iterator in class java.util.AbstractCollection
Returns:
an iterator over this buffer's elements


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