UnboundedFifoBuffer

java.lang.Object
- java.util.AbstractCollection
- - org.apache.commons.collections.buffer.UnboundedFifoBuffer

All Implemented Interfaces:

java.io.Serializable, java.lang.Iterable, java.util.Collection, Buffer
```
public class UnboundedFifoBuffer
extends java.util.AbstractCollection
implements Buffer, java.io.Serializable
```
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.
Since:

Commons Collections 3.0 (previously in main package v2.1)

Version:

$Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`protected java.lang.Object[]`	`buffer` The array of objects in the buffer.
`protected int`	`head` The current head index.
`private static long`	`serialVersionUID` Serialization vesrion
`protected int`	`tail` The current tail index.

Constructor Summary

Constructors
Constructor and Description
`UnboundedFifoBuffer()` Constructs an UnboundedFifoBuffer with the default number of elements.
`UnboundedFifoBuffer(int initialSize)` Constructs an UnboundedFifoBuffer with the specified number of elements.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`add(java.lang.Object obj)` Adds the given element to this buffer.
`private int`	`decrement(int index)` Decrements the internal index.
`java.lang.Object`	`get()` Returns the next object in the buffer.
`private int`	`increment(int index)` Increments the internal index.
`boolean`	`isEmpty()` Returns true if this buffer is empty; false otherwise.
`java.util.Iterator`	`iterator()` Returns an iterator over this buffer's elements.
`private void`	`readObject(java.io.ObjectInputStream in)` Read the buffer in using a custom routine.
`java.lang.Object`	`remove()` Removes the next object from the buffer
`int`	`size()` Returns the number of elements stored in the buffer.
`private void`	`writeObject(java.io.ObjectOutputStream out)` Write the buffer out using a custom routine.

Methods inherited from class java.util.AbstractCollection
addAll, clear, 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, clear, contains, containsAll, equals, hashCode, parallelStream, remove, removeAll, removeIf, retainAll, spliterator, stream, toArray, toArray

Methods inherited from interface java.lang.Iterable
forEach

- Field Detail
  - serialVersionUID
```
private static final long serialVersionUID
```
    Serialization vesrion
    
    See Also:
    
    Constant Field Values
  - buffer
```
protected transient java.lang.Object[] buffer
```
    The array of objects in the buffer.
  - head
```
protected transient int head
```
    The current head index.
  - tail
```
protected transient int tail
```
    The current tail index.
- Constructor Detail
  - 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:
    
    java.lang.IllegalArgumentException - if the size is less than 1
- Method Detail
  - writeObject
```
private void writeObject(java.io.ObjectOutputStream out)
                  throws java.io.IOException
```
    Write the buffer out using a custom routine.
    
    Parameters:
    
    out - the output stream
    
    Throws:
    
    java.io.IOException
  - readObject
```
private void readObject(java.io.ObjectInputStream in)
                 throws java.io.IOException,
                        java.lang.ClassNotFoundException
```
    Read the buffer in using a custom routine.
    
    Parameters:
    
    in - the input stream
    
    Throws:
    
    java.io.IOException
    
    java.lang.ClassNotFoundException
  - 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
  - add
```
public boolean add(java.lang.Object obj)
```
    Adds the given element to this buffer.
    
    Specified by:
    
    add in interface java.util.Collection
    
    Overrides:
    
    add in class java.util.AbstractCollection
    
    Parameters:
    
    obj - the element to add
    
    Returns:
    
    true, always
    
    Throws:
    
    java.lang.NullPointerException - if the given element is null
  - get
```
public java.lang.Object get()
```
    Returns the next object in the buffer.
    
    Specified by:
    
    get in interface Buffer
    
    Returns:
    
    the next object in the buffer
    
    Throws:
    
    BufferUnderflowException - if this buffer is empty
  - remove
```
public java.lang.Object remove()
```
    Removes the next object from the buffer
    
    Specified by:
    
    remove in interface Buffer
    
    Returns:
    
    the removed object
    
    Throws:
    
    BufferUnderflowException - if this buffer is empty
  - increment
```
private int increment(int index)
```
    Increments the internal index.
    
    Parameters:
    
    index - the index to increment
    
    Returns:
    
    the updated index
  - decrement
```
private int decrement(int index)
```
    Decrements the internal index.
    
    Parameters:
    
    index - the index to decrement
    
    Returns:
    
    the updated index
  - iterator
```
public java.util.Iterator iterator()
```
    Returns an iterator over this buffer's elements.
    
    Specified by:
    
    iterator in interface java.lang.Iterable
    
    Specified by:
    
    iterator in interface java.util.Collection
    
    Specified by:
    
    iterator in class java.util.AbstractCollection
    
    Returns:
    
    an iterator over this buffer's elements

Class UnboundedFifoBuffer

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.util.AbstractCollection

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Collection

Methods inherited from interface java.lang.Iterable

Field Detail

serialVersionUID

buffer

head

tail

Constructor Detail

UnboundedFifoBuffer

UnboundedFifoBuffer

Method Detail

writeObject

readObject

size

isEmpty

add

get

remove

increment

decrement

iterator