When is it right for a constructor to throw an exception?

Question

When is it right for a constructor to throw an exception? (Or in the case of Objective C: when is it right for an init\'er to return nil?)

It seems to me that a cons

Answer 1

Speaking strictly from a Java standpoint, any time you initialize a constructor with illegal values, it should throw an exception. That way it does not get constructed in a bad state.