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)
* $
*/
public class ConcurrentHashSet<E> extends MapBackedSet<E> {
private static final long serialVersionUID = 8518578988740277828L;
public ConcurrentHashSet() {
super(new ConcurrentHashMap<E, Boolean>());
}
public ConcurrentHashSet(Collection<E> c) {
super(new ConcurrentHashMap<E, Boolean>(), c);
}
@Override
public boolean 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 {
private static final long serialVersionUID = -8347878570391674042L;
protected final 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
public int size() {
return map.size();
}
@Override
public boolean contains(Object o) {
return map.containsKey(o);
}
@Override
public Iterator<E> iterator() {
return map.keySet().iterator();
}
@Override
public boolean add(E o) {
return map.put(o, Boolean.TRUE) == null;
}
@Override
public boolean remove(Object o) {
return map.remove(o) != null;
}
@Override
public void clear() {
map.clear();
}
}
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