01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one
03: * or more contributor license agreements. See the NOTICE file
04: * distributed with this work for additional information
05: * regarding copyright ownership. The ASF licenses this file
06: * to you under the Apache License, Version 2.0 (the
07: * "License"); you may not use this file except in compliance
08: * with the License. You may obtain a copy of the License at
09: *
10: * http://www.apache.org/licenses/LICENSE-2.0
11: *
12: * Unless required by applicable law or agreed to in writing,
13: * software distributed under the License is distributed on an
14: * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15: * KIND, either express or implied. See the License for the
16: * specific language governing permissions and limitations
17: * under the License.
18: *
19: */
20: package org.apache.mina.util;
21:
22: import java.io.Serializable;
23: import java.util.AbstractSet;
24: import java.util.Collection;
25: import java.util.Iterator;
26: import java.util.Map;
27: import java.util.Set;
28:
29: /**
30: * A {@link Map}-backed {@link Set}.
31: *
32: * @author The Apache MINA Project (dev@mina.apache.org)
33: * @version $Rev: 597692 $, $Date: 2007-11-23 08:56:32 -0700 (Fri, 23 Nov 2007) $
34: */
35: public class MapBackedSet<E> extends AbstractSet<E> implements
36: Serializable {
37:
38: private static final long serialVersionUID = -8347878570391674042L;
39:
40: protected final Map<E, Boolean> map;
41:
42: public MapBackedSet(Map<E, Boolean> map) {
43: this .map = map;
44: }
45:
46: public MapBackedSet(Map<E, Boolean> map, Collection<E> c) {
47: this .map = map;
48: addAll(c);
49: }
50:
51: @Override
52: public int size() {
53: return map.size();
54: }
55:
56: @Override
57: public boolean contains(Object o) {
58: return map.containsKey(o);
59: }
60:
61: @Override
62: public Iterator<E> iterator() {
63: return map.keySet().iterator();
64: }
65:
66: @Override
67: public boolean add(E o) {
68: return map.put(o, Boolean.TRUE) == null;
69: }
70:
71: @Override
72: public boolean remove(Object o) {
73: return map.remove(o) != null;
74: }
75:
76: @Override
77: public void clear() {
78: map.clear();
79: }
80: }
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