org.apache.commons.collections.buffer.CircularFifoBuffer Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of jt-all Show documentation
Provides a single jar containing all JAITools modules which you can use instead of including individual modules in your project. Note: It does not include the Jiffle scripting language or Jiffle image operator.
There is a newer version: 1.4.0
Show newest version
/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2003-2004 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 */
package org.apache.commons.collections.buffer;

import java.util.Collection;

/** 
 * CircularFifoBuffer is a first in first out buffer with a fixed size that
 * replaces its oldest element if full.
 * 
 * The removal order of a CircularFifoBuffer 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 {@link #add(Object)}, {@link #remove()} and {@link #get()} operations
 * all perform in 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 CircularFifoBuffer:
 * 
 *   Buffer fifo = BufferUtils.synchronizedBuffer(new CircularFifoBuffer());
 * 
 * 
 * This buffer prevents null objects from being added.
 * 
 * @since Commons Collections 3.0
 * @version $Revision: 1.2 $ $Date: 2004/01/14 21:43:08 $
 * 
 * @author Stefano Fornari
 * @author Stephen Colebourne
 */
public class CircularFifoBuffer extends BoundedFifoBuffer {

    /**
     * Constructor that creates a buffer with the default size of 32.
     */
    public CircularFifoBuffer() {
        super(32);
    }

    /**
     * Constructor that creates a buffer with the specified size.
     * 
     * @param size  the size of the buffer (cannot be changed)
     * @throws IllegalArgumentException  if the size is less than 1
     */
    public CircularFifoBuffer(int size) {
        super(size);
    }

    /**
     * Constructor that creates a buffer from the specified collection.
     * The collection size also sets the buffer size
     * 
     * @param coll  the collection to copy into the buffer, may not be null
     * @throws NullPointerException if the collection is null
     */
    public CircularFifoBuffer(Collection coll) {
        super(coll);
    }

    /**
     * If the buffer is full, the least recently added element is discarded so
     * that a new element can be inserted.
     *
     * @param element the element to add
     * @return true, always
     */
    public boolean add(Object element) {
        if (isFull()) {
            remove();
        }
        return super.add(element);
    }
    
}