org.apache.commons.collections

Class BufferUtils


public class BufferUtils
extends java.lang.Object

Provides utility methods and decorators for Buffer instances.
Version:
$Revision: 1.20 $ $Date: 2004/04/01 20:12:00 $
Authors:
Paul Jack
Stephen Colebourne
Since:
Commons Collections 2.1

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 (validating) 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

predicatedBuffer

public static Buffer predicatedBuffer(Buffer buffer,
                                      Predicate predicate)
Returns a predicated (validating) buffer backed by the given buffer.

Only objects that pass the test in the given predicate can be added to the buffer. Trying to add an invalid object results in an IllegalArgumentException. It is important not to use the original buffer after invoking this method, as it is a backdoor for adding invalid objects.

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

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

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

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

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

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