class ConcurrentHashMap implements ConcurrentMap<K, V>, Serializable {

    @SuppressWarnings("unchecked") public V put(K key, V value) {
        if (key == null || value == null)
            throw new NullPointerException();
        return (V)internalPut(key, value);
    }

    public  ConcurrentHashMap();
    public  ConcurrentHashMap(int initialCapacity);
    public  ConcurrentHashMap(Map<? extends K, ? extends V> m);
    public  ConcurrentHashMap(int initialCapacity, float loadFactor);
    public  ConcurrentHashMap(int initialCapacity,
                             float loadFactor, int concurrencyLevel);

}