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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.collections;
18  
19  import java.util.Collection;
20  
21  /***
22   * Defines a collection that allows objects to be removed in some well-defined order.
23   * <p>
24   * The removal order can be based on insertion order (eg, a FIFO queue or a
25   * LIFO stack), on access order (eg, an LRU cache), on some arbitrary comparator
26   * (eg, a priority queue) or on any other well-defined ordering.
27   * <p>
28   * Note that the removal order is not necessarily the same as the iteration
29   * order.  A <code>Buffer</code> implementation may have equivalent removal
30   * and iteration orders, but this is not required.
31   * <p>
32   * This interface does not specify any behavior for 
33   * {@link Object#equals(Object)} and {@link Object#hashCode} methods.  It
34   * is therefore possible for a <code>Buffer</code> implementation to also
35   * also implement {@link java.util.List}, {@link java.util.Set} or 
36   * {@link Bag}.
37   * <p>
38   * <strong>Note:</strong> this class should be bytecode-identical to the 
39   * version in commons collections. This is required to allow backwards 
40   * compability with both previous versions of BeanUtils and also allow 
41   * coexistance with both collections 2.1 and 3.0.
42   *
43   * @since Commons Collections 2.1
44   * @version $Revision: 555824 $ $Date: 2007-07-13 01:27:15 +0100 (Fri, 13 Jul 2007) $
45   * 
46   * @author Avalon
47   * @author Berin Loritsch
48   * @author Paul Jack
49   * @author Stephen Colebourne
50   */
51  public interface Buffer extends Collection {
52  
53      /***
54       * Gets and removes the next object from the buffer.
55       *
56       * @return the next object in the buffer, which is also removed
57       * @throws BufferUnderflowException if the buffer is already empty
58       */
59      Object remove();
60  
61      /***
62       * Gets the next object from the buffer without removing it.
63       *
64       * @return the next object in the buffer, which is not removed
65       * @throws BufferUnderflowException if the buffer is empty
66       */
67      Object get();
68  
69  }