## 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

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