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org.apache.commons.collections

Class BoundedFifoBuffer

AbstractCollection
|
+--org.apache.commons.collections.BoundedFifoBuffer

All Implemented Interfaces:
BoundedCollection, Buffer


public class BoundedFifoBuffer
extends AbstractCollection
implements Buffer, BoundedCollection

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
Authors:
Avalon
Berin Loritsch
Paul Jack
Stephen Colebourne
Herve Quiroz

Constructor Summary

BoundedFifoBuffer()

Constructs a new BoundedFifoBuffer big enough to hold 32 elements.

BoundedFifoBuffer(int size)

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

BoundedFifoBuffer(Collection coll)

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

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.

boolean

isFull()

Returns true if this collection is full and no new elements can be added.

Iterator

iterator()

Returns an iterator over this buffer's elements.

int

maxSize()

Gets the maximum size of the collection (the bound).

Object

remove()

Removes the least recently inserted element from this buffer.

int

size()

Returns the number of elements stored in the buffer.

Constructor Details

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, may not be null
Throws:
- if the collection is null

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:
- if the size is less than 1

Method Details

add

public boolean add(Object element)

Adds the given element to this buffer.

Parameters:
element - the element to add
Returns:
true, always
Throws:
- if the given element is null
BufferOverflowException - if this buffer is full

clear

public void clear()

Clears this buffer.


get

public Object get()

Returns the least recently inserted element in this 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.

Returns:
true if this buffer is empty

isFull

public boolean isFull()

Returns true if this collection is full and no new elements can be added.

Returns:
true if the collection is full

iterator

public Iterator iterator()

Returns an iterator over this buffer's elements.

Returns:
an iterator over this buffer's elements

maxSize

public int maxSize()

Gets the maximum size of the collection (the bound).

Returns:
the maximum number of elements the collection can hold

remove

public Object remove()

Removes the least recently inserted element from this 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.

Returns:
this buffer's size