/*
* Copyright 2003-2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
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.
* <p>
* The removal order of a <code>CircularFifoBuffer</code> 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.
* <p>
* The {@link #add(Object)}, {@link #remove()} and {@link #get()} operations
* all perform in constant time. All other operations perform in linear
* time or worse.
* <p>
* Note that this implementation is not synchronized. The following can be
* used to provide synchronized access to your <code>CircularFifoBuffer</code>:
* <pre>
* Buffer fifo = BufferUtils.synchronizedBuffer(new CircularFifoBuffer());
* </pre>
* <p>
* This buffer prevents null objects from being added.
* <p>
* This class is Serializable from Commons Collections 3.1.
*
* @since Commons Collections 3.0
* @version $Revision: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $
*
* @author Stefano Fornari
* @author Stephen Colebourne
*/
public class CircularFifoBuffer extends BoundedFifoBuffer {
/** Serialization version */
private static final long serialVersionUID = -8423413834657610406L;
/**
* 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);
}
}