01: /*
02: * Copyright 2002-2004 The Apache Software Foundation
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
10: * Unless required by applicable law or agreed to in writing, software
11: * distributed under the License is distributed on an "AS IS" BASIS,
12: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13: * See the License for the specific language governing permissions and
14: * limitations under the License.
15: */
16: package org.apache.commons.collections;
17:
18: import java.util.Collection;
19:
20: /**
21: * Defines a collection that allows objects to be removed in some well-defined order.
22: * <p>
23: * The removal order can be based on insertion order (eg, a FIFO queue or a
24: * LIFO stack), on access order (eg, an LRU cache), on some arbitrary comparator
25: * (eg, a priority queue) or on any other well-defined ordering.
26: * <p>
27: * Note that the removal order is not necessarily the same as the iteration
28: * order. A <code>Buffer</code> implementation may have equivalent removal
29: * and iteration orders, but this is not required.
30: * <p>
31: * This interface does not specify any behavior for
32: * {@link Object#equals(Object)} and {@link Object#hashCode} methods. It
33: * is therefore possible for a <code>Buffer</code> implementation to also
34: * also implement {@link java.util.List}, {@link java.util.Set} or
35: * {@link Bag}.
36: *
37: * @since Commons Collections 2.1
38: * @version $Revision: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $
39: *
40: * @author Avalon
41: * @author Berin Loritsch
42: * @author Paul Jack
43: * @author Stephen Colebourne
44: */
45: public interface Buffer extends Collection {
46:
47: /**
48: * Gets and removes the next object from the buffer.
49: *
50: * @return the next object in the buffer, which is also removed
51: * @throws BufferUnderflowException if the buffer is already empty
52: */
53: Object remove();
54:
55: /**
56: * Gets the next object from the buffer without removing it.
57: *
58: * @return the next object in the buffer, which is not removed
59: * @throws BufferUnderflowException if the buffer is empty
60: */
61: Object get();
62:
63: }
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