Any implementation of Map, i.e. two keys?

Question

I need a map that has two keys, e.g.

Map2 _employees;

So that I can

_empl         


        

Answer 1

I imagine the main key would be empId, so I would build a Map with that as the key, i.e. empId ---> Employee. All other unique attributes (e.g. ssn) would be treated as secondary and will use separate Maps as a lookup table for empId (e.g. ssn ---> empId).

This implementation makes it easy to add/remove employees, since you only need to change one Map, i.e. empId ---> Employee; the other Maps can be rebuilt only when needed.