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jsync.io is a non-blocking, event-driven networking framework for Java

There is a newer version: 1.10.13

/*
 * Copyright (c) 2011-2013 The original author or authors
 * ------------------------------------------------------
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Apache License v2.0 which accompanies this distribution.
 *
 *     The Eclipse Public License is available at
 *     http://www.eclipse.org/legal/epl-v10.html
 *
 *     The Apache License v2.0 is available at
 *     http://www.opensource.org/licenses/apache2.0.php
 *
 * You may elect to redistribute this code under either of these licenses.
 */

package io.jsync.impl;

import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @author Tim Fox
 */
public class ConcurrentHashSet implements Set {

    private static final Object OBJ = new Object();
    private final Map map;

    public ConcurrentHashSet(int size) {
        map = new ConcurrentHashMap<>(size);
    }

    public ConcurrentHashSet() {
        map = new ConcurrentHashMap<>();
    }

    @Override
    public int size() {
        return map.size();
    }

    @Override
    public boolean isEmpty() {
        return map.isEmpty();
    }

    @Override
    public boolean contains(Object o) {
        return map.containsKey(o);
    }

    @Override
    public Iterator iterator() {
        return map.keySet().iterator();
    }

    @Override
    public Object[] toArray() {
        return map.keySet().toArray();
    }

    @Override
    public  T[] toArray(T[] a) {
        return map.keySet().toArray(a);
    }

    @Override
    public boolean add(E e) {
        return map.put(e, OBJ) == null;
    }

    @Override
    public boolean remove(Object o) {
        return map.remove(o) == null;
    }

    @Override
    public boolean containsAll(Collection c) {
        return map.keySet().containsAll(c);
    }

    @Override
    public boolean addAll(Collection c) {
        boolean changed = false;
        for (E e : c) {
            if (map.put(e, OBJ) == null) {
                changed = true;
            }
        }
        return changed;
    }

    @Override
    public boolean retainAll(Collection c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean removeAll(Collection c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void clear() {
        map.clear();
    }
}