BoundedFifoBuffer

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

All Implemented Interfaces:

java.io.Serializable, java.lang.Iterable, java.util.Collection, BoundedCollection, Buffer

Direct Known Subclasses:

CircularFifoBuffer
```
public class BoundedFifoBuffer
extends java.util.AbstractCollection
implements Buffer, BoundedCollection, java.io.Serializable
```
The BoundedFifoBuffer is a very efficient implementation of Buffer that is of a fixed size.
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.
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
`private java.lang.Object[]`	`elements` Underlying storage array
`private int`	`end` Index mod maxElements of the array position following the last buffer element.
`private boolean`	`full` Flag to indicate if the buffer is currently full.
`private int`	`maxElements` Capacity of the buffer
`private static long`	`serialVersionUID` Serialization version
`private int`	`start` Array index of first (oldest) buffer element

Constructor Summary

Constructors
Constructor and Description
`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

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`add(java.lang.Object element)` Adds the given element to this buffer.
`void`	`clear()` Clears this buffer.
`private int`	`decrement(int index)` Decrements the internal index.
`java.lang.Object`	`get()` Returns the least recently inserted element in this buffer.
`private int`	`increment(int index)` Increments the internal index.
`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.
`java.util.Iterator`	`iterator()` Returns an iterator over this buffer's elements.
`int`	`maxSize()` Gets the maximum size of the collection (the bound).
`private void`	`readObject(java.io.ObjectInputStream in)` Read the buffer in using a custom routine.
`java.lang.Object`	`remove()` Removes the least recently inserted element from this 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, 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, 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 version
    
    See Also:
    
    Constant Field Values
  - elements
```
private transient java.lang.Object[] elements
```
    Underlying storage array
  - start
```
private transient int start
```
    Array index of first (oldest) buffer element
  - end
```
private transient int end
```
    Index mod maxElements of the array position following the last buffer element. Buffer elements start at elements[start] and "wrap around" elements[maxElements-1], ending at elements[decrement(end)]. For example, elements = {c,a,b}, start=1, end=1 corresponds to the buffer [a,b,c].
  - full
```
private transient boolean full
```
    Flag to indicate if the buffer is currently full.
  - maxElements
```
private final int maxElements
```
    Capacity of the buffer
- 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, may not be null
    
    Throws:
    
    java.lang.NullPointerException - if the collection is null
- 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
  - isFull
```
public boolean isFull()
```
    Returns true if this collection is full and no new elements can be added.
    
    Specified by:
    
    isFull in interface BoundedCollection
    
    Returns:
    
    true if the collection is full
  - maxSize
```
public int maxSize()
```
    Gets the maximum size of the collection (the bound).
    
    Specified by:
    
    maxSize in interface BoundedCollection
    
    Returns:
    
    the maximum number of elements the collection can hold
  - 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
  - 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 BoundedFifoBuffer

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

elements

start

end

full

maxElements

Constructor Detail

BoundedFifoBuffer

BoundedFifoBuffer

BoundedFifoBuffer

Method Detail

writeObject

readObject

size

isEmpty

isFull

maxSize

clear

add

get

remove

increment

decrement

iterator