@Override public int compareTo(ChildContainer o) { // Compare by surname. int ret = child.getSurname().compareTo(o.getChild().getSurname()); if (ret == 0) { // Surname is the same, just by firstname. ret = child.getFirstname().compareTo(o.getChild().getFirstname()); // If still 0, use the id. if (ret == 0) { ret = child.getChildid().compareTo(o.getChild().getChildid()); } } return ret; }