在Java中寻找ConcurrentHashSet吗？

方法一：Collections.newSetFromMap(new ConcurrentHashMap<Object,Boolean>())

方法二：（引用自Apache Mina，位置org.apache.mina.util.ConcurrentHashSet）

package org.apache.mina.util;import java.util.Collection;import java.util.Set;import java.util.concurrent.ConcurrentHashMap;import java.util.concurrent.ConcurrentMap;/** * A {@link ConcurrentHashMap}-backed {@link Set}. * * @author <a href="http://mina.apache.org" mce_href="http://mina.apache.org">Apache MINA Project</a> */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; }}