private int compareUnit(App a) {
if (!hasUnit()) return a.hasUnit() ? 1 : compareAppapp(a);
else if (!a.hasUnit()) return -1;
else {
int c = unit.compareTo(a.getUnit());
return c != 0 ? c : compareAppapp(a);
}
}
private int compareAppapp(App a) {
if (!hasAppapp()) return a.hasAppapp() ? 1 : 0;
else if (!a.hasAppapp()) return -1;
else return appapp.compareTo(a.getAppapp());
}