private void reverse() {
		Element tmpf = firstElement;
		Element tmps = firstElement.getNextElement();
		Element tmpt = firstElement.getNextElement().getNextElement();
		tmpf.setNextElement(null);
		while (tmpt.getNextElement() != null) {
			tmps.setNextElement(tmpf);
			tmpf = tmps;
			tmps = tmpt;
			tmpt = tmpt.getNextElement();
		}
		tmps.setNextElement(tmpf);
		tmpt.setNextElement(tmps);
		firstElement = tmpt;
		if (reversed) {
			reversed = false;
		} else {
			reversed = true;
		}
	}