code: public void trimToSize() {
  		if (_size < _data.length) {
  			_data = _size == 0
  				? EMPTY_ARRAY
  				: copyOf(_data, _size);
  		}
  	}
docs: Trims the capacity of this <tt>ArrayList</tt> instance to be the list's
  current size.  An application can use this operation to minimize the
  storage of an <tt>ArrayList</tt> instance.