null: was is the default returned value?

What value does the jdbc driver return from the various getXXX()
functions when the DB return value is null?

I've been having some trouble using getObject() and getStr() on
ResultSets that contain null values for some fields.

If I do Object o = r.getObject("col") and the returned value is null I
get a nullPointeException. But for String s = r.getStr("col") I get a
value that prints out as "null" ... so if getStr() works I don't
understand why getObject() doesn't ...

Thanks,

Jc