Concurrent HashSet
/** *Copyright [2009-2010] [dennis zhuang(killme2008@gmail.com)] *Licensed under the Apache License, Version 2.0 (the "License"); *you may not use this file except in compliance with the License. *You may obtain a copy of the License at * http://www.apache.org/licenses/LICENSE-2.0 *Unless required by applicable law or agreed to in writing, *software distributed under the License is distributed on an "AS IS" BASIS, *WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, *either express or implied. See the License for the specific language governing permissions and limitations under the License *//** *Copyright [2009-2010] [dennis zhuang(killme2008@gmail.com)] *Licensed under the Apache License, Version 2.0 (the "License"); *you may not use this file except in compliance with the License. *You may obtain a copy of the License at * http://www.apache.org/licenses/LICENSE-2.0 *Unless required by applicable law or agreed to in writing, *software distributed under the License is distributed on an "AS IS" BASIS, *WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, *either express or implied. See the License for the specific language governing permissions and limitations under the License *///package com.google.code.yanf4j.util; import java.io.Serializable; import java.util.AbstractSet; import java.util.Collection; import java.util.Iterator; import java.util.Map; import java.util.Set; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.ConcurrentMap; /** * A {@link ConcurrentHashMap}-backed {@link Set}. * * @author The Apache MINA Project (dev@mina.apache.org) * @version $Rev: 597692 $, $Date: 2007-11-23 08:56:32 -0700 (Fri, 23 Nov 2007) * $ */publicclass ConcurrentHashSet<E> extends MapBackedSet<E> { privatestaticfinallong serialVersionUID = 8518578988740277828L; public ConcurrentHashSet() { super(new ConcurrentHashMap<E, Boolean>()); } public ConcurrentHashSet(Collection<E> c) { super(new ConcurrentHashMap<E, Boolean>(), c); } @Override publicboolean add(E o) { Boolean answer = ((ConcurrentMap<E, Boolean>) map).putIfAbsent(o, Boolean.TRUE); return answer == null; } } /** * A {@link Map}-backed {@link Set}. * * @author The Apache MINA Project (dev@mina.apache.org) * @version $Rev: 597692 $, $Date: 2007-11-23 08:56:32 -0700 (Fri, 23 Nov 2007) * $ */class MapBackedSet<E> extends AbstractSet<E> implements Serializable { privatestaticfinallong serialVersionUID = -8347878570391674042L; protectedfinal Map<E, Boolean> map; public MapBackedSet(Map<E, Boolean> map) { this.map = map; } public MapBackedSet(Map<E, Boolean> map, Collection<E> c) { this.map = map; addAll(c); } @Override publicint size() { return map.size(); } @Override publicboolean contains(Object o) { return map.containsKey(o); } @Override public Iterator<E> iterator() { return map.keySet().iterator(); } @Override publicboolean add(E o) { return map.put(o, Boolean.TRUE) == null; } @Override publicboolean remove(Object o) { return map.remove(o) != null; } @Override publicvoid clear() { map.clear(); } } Related examples in the same category
