    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements.  See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache License, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License.  You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the License for the specific language governing permissions and
    015     * limitations under the License.
    016     */
    017    package org.apache.commons.collections;
    018
    019    import java.util.Collection;
    020
    021    /**
    022     * Defines a collection that allows objects to be removed in some well-defined order.
    023     * <p>
    024     * The removal order can be based on insertion order (eg, a FIFO queue or a
    025     * LIFO stack), on access order (eg, an LRU cache), on some arbitrary comparator
    026     * (eg, a priority queue) or on any other well-defined ordering.
    027     * <p>
    028     * Note that the removal order is not necessarily the same as the iteration
    029     * order.  A <code>Buffer</code> implementation may have equivalent removal
    030     * and iteration orders, but this is not required.
    031     * <p>
    032     * This interface does not specify any behavior for
    033     * {@link Object#equals(Object)} and {@link Object#hashCode} methods.  It
    034     * is therefore possible for a <code>Buffer</code> implementation to also
    035     * also implement {@link java.util.List}, {@link java.util.Set} or
    036     * {@link Bag}.
    037     * <p>
    038     * <strong>Note:</strong> this class should be bytecode-identical to the
    039     * version in commons collections. This is required to allow backwards
    040     * compability with both previous versions of BeanUtils and also allow
    041     * coexistance with both collections 2.1 and 3.0.
    042     *
    043     * @since Commons Collections 2.1
    044     * @version $Revision: 555824 $ $Date: 2007-07-13 01:27:15 +0100 (Fri, 13 Jul 2007) $
    045     *
    046     * @author Avalon
    047     * @author Berin Loritsch
    048     * @author Paul Jack
    049     * @author Stephen Colebourne
    050     */
    051    public interface Buffer extends Collection {
    052
    053        /**
    054         * Gets and removes the next object from the buffer.
    055         *
    056         * @return the next object in the buffer, which is also removed
    057         * @throws BufferUnderflowException if the buffer is already empty
    058         */
    059        Object remove();
    060
    061        /**
    062         * Gets the next object from the buffer without removing it.
    063         *
    064         * @return the next object in the buffer, which is not removed
    065         * @throws BufferUnderflowException if the buffer is empty
    066         */
    067        Object get();
    068
    069    }