Class UnboundedFifoBuffer
java.lang.Object
java.util.AbstractCollection
org.apache.commons.collections.buffer.UnboundedFifoBuffer
- All Implemented Interfaces:
Serializable
,Iterable
,Collection
,Buffer
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:
-
Field Summary
FieldsModifier and TypeFieldDescriptionprotected Object[]
The array of objects in the buffer.protected int
The current head index.private static final long
Serialization vesrionprotected int
The current tail index. -
Constructor Summary
ConstructorsConstructorDescriptionConstructs an UnboundedFifoBuffer with the default number of elements.UnboundedFifoBuffer
(int initialSize) Constructs an UnboundedFifoBuffer with the specified number of elements. -
Method Summary
Modifier and TypeMethodDescriptionboolean
Adds the given element to this buffer.private int
decrement
(int index) Decrements the internal index.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.iterator()
Returns an iterator over this buffer's elements.private void
Read the buffer in using a custom routine.remove()
Removes the next object from the bufferint
size()
Returns the number of elements stored in the buffer.private void
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
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Field Details
-
serialVersionUID
private static final long serialVersionUIDSerialization vesrion- See Also:
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buffer
The array of objects in the buffer. -
head
protected transient int headThe current head index. -
tail
protected transient int tailThe current tail index.
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-
Constructor Details
-
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:
IllegalArgumentException
- if the size is less than 1
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-
Method Details
-
writeObject
Write the buffer out using a custom routine.- Parameters:
out
- the output stream- Throws:
IOException
-
readObject
Read the buffer in using a custom routine.- Parameters:
in
- the input stream- Throws:
IOException
ClassNotFoundException
-
size
public int size()Returns the number of elements stored in the buffer.- Specified by:
size
in interfaceCollection
- Specified by:
size
in classAbstractCollection
- Returns:
- this buffer's size
-
isEmpty
public boolean isEmpty()Returns true if this buffer is empty; false otherwise.- Specified by:
isEmpty
in interfaceCollection
- Overrides:
isEmpty
in classAbstractCollection
- Returns:
- true if this buffer is empty
-
add
Adds the given element to this buffer.- Specified by:
add
in interfaceCollection
- Overrides:
add
in classAbstractCollection
- Parameters:
obj
- the element to add- Returns:
- true, always
- Throws:
NullPointerException
- if the given element is null
-
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
-
remove
Removes the next object from the buffer- Specified by:
remove
in interfaceBuffer
- 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
Returns an iterator over this buffer's elements.- Specified by:
iterator
in interfaceCollection
- Specified by:
iterator
in interfaceIterable
- Specified by:
iterator
in classAbstractCollection
- Returns:
- an iterator over this buffer's elements
-