Class UnboundedFifoBuffer
- java.lang.Object
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- java.util.AbstractCollection
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- org.apache.commons.collections.buffer.UnboundedFifoBuffer
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- 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 ofBuffer
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()
andget()
operations perform in constant time. Theadd(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
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Field Summary
Fields Modifier and Type Field 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 vesrionprotected int
tail
The current tail index.
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Constructor Summary
Constructors Constructor Description UnboundedFifoBuffer()
Constructs an UnboundedFifoBuffer with the default number of elements.UnboundedFifoBuffer(int initialSize)
Constructs an UnboundedFifoBuffer with the specified number of elements.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method 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 bufferint
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
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Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
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Field Detail
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serialVersionUID
private static final long serialVersionUID
Serialization vesrion- See Also:
- Constant Field Values
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buffer
protected transient java.lang.Object[] buffer
The array of objects in the buffer.
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head
protected transient int head
The current head index.
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tail
protected transient int tail
The current tail index.
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Constructor Detail
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UnboundedFifoBuffer
public UnboundedFifoBuffer()
Constructs an UnboundedFifoBuffer with the default number of elements. It is exactly the same as performing the following:new UnboundedFifoBuffer(32);
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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
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Method Detail
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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
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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
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size
public int size()
Returns the number of elements stored in the buffer.- Specified by:
size
in interfacejava.util.Collection
- Specified by:
size
in classjava.util.AbstractCollection
- Returns:
- this buffer's size
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isEmpty
public boolean isEmpty()
Returns true if this buffer is empty; false otherwise.- Specified by:
isEmpty
in interfacejava.util.Collection
- Overrides:
isEmpty
in classjava.util.AbstractCollection
- Returns:
- true if this buffer is empty
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add
public boolean add(java.lang.Object obj)
Adds the given element to this buffer.- Specified by:
add
in interfacejava.util.Collection
- Overrides:
add
in classjava.util.AbstractCollection
- Parameters:
obj
- the element to add- Returns:
- true, always
- Throws:
java.lang.NullPointerException
- if the given element is null
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get
public java.lang.Object get()
Returns the next object in the buffer.- Specified by:
get
in interfaceBuffer
- Returns:
- the next object in the buffer
- Throws:
BufferUnderflowException
- if this buffer is empty
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remove
public java.lang.Object remove()
Removes the next object from the buffer- Specified by:
remove
in interfaceBuffer
- Returns:
- the removed object
- Throws:
BufferUnderflowException
- if this buffer is empty
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increment
private int increment(int index)
Increments the internal index.- Parameters:
index
- the index to increment- Returns:
- the updated index
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decrement
private int decrement(int index)
Decrements the internal index.- Parameters:
index
- the index to decrement- Returns:
- the updated index
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iterator
public java.util.Iterator iterator()
Returns an iterator over this buffer's elements.- Specified by:
iterator
in interfacejava.util.Collection
- Specified by:
iterator
in interfacejava.lang.Iterable
- Specified by:
iterator
in classjava.util.AbstractCollection
- Returns:
- an iterator over this buffer's elements
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