säkki

Here's the problem little simplified:

I have made two classes Person and CardIndex.

I created Objects from both
Person myP = new Person("FirstName", "LastName");
CardIndex cInd = new CardIndex();

CardIndex is basically a vector where I dump those Persons.

Classes have some other stuff in them too, and Person is a super-class for two other Classes, so in CardIndex-vector can be at least three kind of classes or something like that.
Problem:
I have to sort the cInd by LastName using sort()-method. I'm lost

//Collections.sort(cInd**!*"*#) brainMalfunction. Thanks for any help.