/** Empties the map. */
  public void clear() {
    super.clear();
    byte[] keys = _set;
    long[] vals = _values;
    byte[] states = _states;

    Arrays.fill(_set, 0, _set.length, (byte) 0);
    Arrays.fill(_values, 0, _values.length, (long) 0);
    Arrays.fill(_states, 0, _states.length, FREE);
  }
 /**
  * removes the mapping at <tt>index</tt> from the map.
  *
  * @param index an <code>int</code> value
  */
 protected void removeAt(int index) {
   _values[index] = (long) 0;
   super.removeAt(index); // clear key, state; adjust size
 }