private boolean compareArzt(Arzt first, Arzt second) { boolean strings = (first.getPrename().equals(second.getPrename()) && first.getSurname().equals(second.getSurname()) && first.getBehandelndeKrankheit().equals(second.getBehandelndeKrankheit())); boolean op = true; if (first.getOpTermin() == null && second.getOpTermin() == null) { op = true; } else if (first.getOpTermin() == null ^ second.getOpTermin() == null) { op = false; } else if (first.getOpTermin().compareTo(second.getOpTermin()) != 0) { op = false; } return strings && op; }