public class

UnboundedFifoBuffer

extends AbstractCollection<E>
implements Serializable Buffer
java.lang.Object
   ↳ java.util.AbstractCollection<E>
     ↳ org.apache.commons.collections.buffer.UnboundedFifoBuffer

Class Overview

UnboundedFifoBuffer is a very efficient implementation of Buffer that can grow to any size. 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.

Summary

Fields
protected Object[] buffer The array of objects in the buffer.
protected int head The current head index.
protected int tail The current tail index.
Public Constructors
UnboundedFifoBuffer()
Constructs an UnboundedFifoBuffer with the default number of elements.
UnboundedFifoBuffer(int initialSize)
Constructs an UnboundedFifoBuffer with the specified number of elements.
Public Methods
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.
[Expand]
Inherited Methods
From class java.util.AbstractCollection
From class java.lang.Object
From interface java.lang.Iterable
From interface java.util.Collection
From interface org.apache.commons.collections.Buffer

Fields

protected Object[] buffer

The array of objects in the buffer.

protected int head

The current head index.

protected int tail

The current tail index.

Public Constructors

public UnboundedFifoBuffer ()

Constructs an UnboundedFifoBuffer with the default number of elements. It is exactly the same as performing the following: 

   new UnboundedFifoBuffer(32);

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
IllegalArgumentException if the size is less than 1

Public Methods

public boolean add (Object obj)

Adds the given element to this buffer.

Parameters
obj the element to add
Returns
  • true, always
Throws
NullPointerException if the given element is null

public Object get ()

Returns the next object in the buffer.

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

public boolean isEmpty ()

Returns true if this buffer is empty; false otherwise.

Returns
  • true if this buffer is empty

public Iterator iterator ()

Returns an iterator over this buffer's elements.

Returns
  • an iterator over this buffer's elements

public Object remove ()

Removes the next object from the buffer

Returns
  • the removed object
Throws
BufferUnderflowException if this buffer is empty

public int size ()

Returns the number of elements stored in the buffer.

Returns
  • this buffer's size