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

Version:

$Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $

Author:

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	blockingBuffer(Buffer buffer, long timeoutMillis) Returns a synchronized buffer backed by the given buffer that will block on Buffer.get() and Buffer.remove() operations until timeout expires.
static Buffer	boundedBuffer(Buffer buffer, int maximumSize) Returns a synchronized buffer backed by the given buffer that will block on Collection.add(Object) and Collection.addAll(java.util.Collection) until enough object(s) are removed from the buffer to allow the object(s) to be added and still maintain the maximum size.
static Buffer	boundedBuffer(Buffer buffer, int maximumSize, long timeoutMillis) Returns a synchronized buffer backed by the given buffer that will block on Collection.add(Object) and Collection.addAll(java.util.Collection) until enough object(s) are removed from the buffer to allow the object(s) to be added and still maintain the maximum size or the timeout expires.
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, java.lang.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.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

EMPTY_BUFFER

public static final Buffer EMPTY_BUFFER

An empty unmodifiable buffer.

Constructor Detail

BufferUtils

public BufferUtils()

BufferUtils should not normally be instantiated.

Method Detail

synchronizedBuffer

public static Buffer synchronizedBuffer(Buffer buffer)

Returns a synchronized buffer backed by the given buffer. Much like the synchronized collections returned by 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:

java.lang.IllegalArgumentException - if the Buffer is null

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:

java.lang.IllegalArgumentException - if the Buffer is null

blockingBuffer

public static Buffer blockingBuffer(Buffer buffer,
                                    long timeoutMillis)

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

timeoutMillis - the timeout value in milliseconds, zero or less for no timeout

Returns:

a blocking buffer backed by that buffer

Throws:

java.lang.IllegalArgumentException - if the Buffer is null

Since:

Commons Collections 3.2

boundedBuffer

public static Buffer boundedBuffer(Buffer buffer,
                                   int maximumSize)

Returns a synchronized buffer backed by the given buffer that will block on Collection.add(Object) and Collection.addAll(java.util.Collection) until enough object(s) are removed from the buffer to allow the object(s) to be added and still maintain the maximum size.

Parameters:

buffer - the buffer to make bounded, must not be null

maximumSize - the maximum size

Returns:

a bounded buffer backed by the given buffer

Throws:

java.lang.IllegalArgumentException - if the given buffer is null

Since:

Commons Collections 3.2

boundedBuffer

public static Buffer boundedBuffer(Buffer buffer,
                                   int maximumSize,
                                   long timeoutMillis)

Returns a synchronized buffer backed by the given buffer that will block on Collection.add(Object) and Collection.addAll(java.util.Collection) until enough object(s) are removed from the buffer to allow the object(s) to be added and still maintain the maximum size or the timeout expires.

Parameters:

buffer - the buffer to make bounded, must not be null

maximumSize - the maximum size

timeoutMillis - the timeout value in milliseconds, zero or less for no timeout

Returns:

a bounded buffer backed by the given buffer

Throws:

java.lang.IllegalArgumentException - if the given buffer is null

Since:

Commons Collections 3.2

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:

java.lang.IllegalArgumentException - if the Buffer is null

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

Throws:

java.lang.IllegalArgumentException - if the Buffer or Predicate is null

typedBuffer

public static Buffer typedBuffer(Buffer buffer,
                                 java.lang.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:

java.lang.IllegalArgumentException - if the buffer or type 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:

java.lang.IllegalArgumentException - if the Buffer or Transformer is null