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org.apache.commons.collections

Class BufferUtils

java.lang.Object
|
+--org.apache.commons.collections.BufferUtils


public class BufferUtils
extends java.lang.Object

Provides utility methods and decorators for Buffer instances.
Since:
Commons Collections 2.1
Authors:
Paul Jack
Stephen Colebourne

Field Summary

static Buffer

EMPTY_BUFFER

An empty unmodifiable buffer.

Constructor Summary

BufferUtils()

BufferUtils should not normally be instantiated.

Method Summary

static Buffer

blockingBuffer(Buffer buffer)

Returns a synchronized buffer backed by the given buffer that will block on Buffer#get() and Buffer#remove() operations.

static Buffer

predicatedBuffer(Buffer buffer, Predicate predicate)

Returns a predicated buffer backed by the given buffer.

static Buffer

synchronizedBuffer(Buffer buffer)

Returns a synchronized buffer backed by the given buffer.

static Buffer

transformedBuffer(Buffer buffer, Transformer transformer)

Returns a transformed buffer backed by the given buffer.

static Buffer

typedBuffer(Buffer buffer, Class type)

Returns a typed buffer backed by the given buffer.

static Buffer

unmodifiableBuffer(Buffer buffer)

Returns an unmodifiable buffer backed by the given buffer.

Field Details

EMPTY_BUFFER

public static final Buffer EMPTY_BUFFER

An empty unmodifiable buffer.

Constructor Details

BufferUtils

public BufferUtils()

BufferUtils should not normally be instantiated.

Method Details

blockingBuffer

public static Buffer blockingBuffer(Buffer buffer)

Returns a synchronized buffer backed by the given buffer that will block on Buffer.get() and Buffer.remove() operations. If the buffer is empty, then the Buffer.get() and Buffer.remove() operations will block until new elements are added to the buffer, rather than immediately throwing a BufferUnderflowException.

Parameters:
buffer - the buffer to synchronize, must not be null
Returns:
a blocking buffer backed by that buffer
Throws:
- if the Buffer is null

predicatedBuffer

public static Buffer predicatedBuffer(Buffer buffer, Predicate predicate)

Returns a predicated buffer backed by the given buffer. Elements are evaluated with the given predicate before being added to the buffer. If the predicate evaluation returns false, then an IllegalArgumentException is raised and the element is not added to the buffer.

Parameters:
buffer - the buffer to predicate, must not be null
predicate - the predicate used to evaluate new elements, must not be null
Returns:
a predicated buffer
Throws:
- if the Buffer or Predicate is null

synchronizedBuffer

public static Buffer synchronizedBuffer(Buffer buffer)

Returns a synchronized buffer backed by the given buffer. Much like the synchronized collections returned by java.util.Collections, you must manually synchronize on the returned buffer's iterator to avoid non-deterministic behavior:
 Buffer b = BufferUtils.synchronizedBuffer(myBuffer);
 synchronized (b) {
     Iterator i = b.iterator();
     while (i.hasNext()) {
         process (i.next());
     }
 }

Parameters:
buffer - the buffer to synchronize, must not be null
Returns:
a synchronized buffer backed by that buffer
Throws:
- if the Buffer is null

transformedBuffer

public static Buffer transformedBuffer(Buffer buffer, Transformer transformer)

Returns a transformed buffer backed by the given buffer.

Each object is passed through the transformer as it is added to the Buffer. It is important not to use the original buffer after invoking this method, as it is a backdoor for adding untransformed objects.

Parameters:
buffer - the buffer to predicate, must not be null
transformer - the transformer for the buffer, must not be null
Returns:
a transformed buffer backed by the given buffer
Throws:
- if the Buffer or Transformer is null

typedBuffer

public static Buffer typedBuffer(Buffer buffer, Class type)

Returns a typed buffer backed by the given buffer.

Only elements of the specified type can be added to the buffer.

Parameters:
buffer - the buffer to predicate, must not be null
type - the type to allow into the buffer, must not be null
Returns:
a typed buffer
Throws:
- if the buffer or type is null

unmodifiableBuffer

public static Buffer unmodifiableBuffer(Buffer buffer)

Returns an unmodifiable buffer backed by the given buffer.

Parameters:
buffer - the buffer to make unmodifiable, must not be null
Returns:
an unmodifiable buffer backed by that buffer
Throws:
- if the Buffer is null