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 * 038 * @since Commons Collections 2.1 039 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ 040 * 041 * @author Avalon 042 * @author Berin Loritsch 043 * @author Paul Jack 044 * @author Stephen Colebourne 045 */ 046 public interface Buffer extends Collection { 047 048 /** 049 * Gets and removes the next object from the buffer. 050 * 051 * @return the next object in the buffer, which is also removed 052 * @throws BufferUnderflowException if the buffer is already empty 053 */ 054 Object remove(); 055 056 /** 057 * Gets the next object from the buffer without removing it. 058 * 059 * @return the next object in the buffer, which is not removed 060 * @throws BufferUnderflowException if the buffer is empty 061 */ 062 Object get(); 063 064 }