public static TripleIDComparatorSPO getInstance() { if(instance==null) { instance = new TripleIDComparatorSPO(); } return instance; }
public static Comparator<TripleID> getComparator(TripleComponentOrder order) { if(order==TripleComponentOrder.SPO) { return TripleIDComparatorSPO.getInstance(); } return new TripleIDComparator(order); }