private int copmareDrug(Drug d) {
if (!hasDrug()) return d.hasDrug() ? 1 : 0;
else if (!d.hasDrug()) return -1;
else {
int c = drug.compareTo(d.getDrug());
return c;
}
}
public void addTrade(Drug drug) {
if (trade == null) trade = new ArrayList<Drug>();
trade.add(drug);
drug.setGeneric(this);
}