I'm not sure if I understood your actual question: is it something like: "how to make use of the variables passed to the constructor in the getResultSet() method, so that once created, a dbQuery instance can return the result by simply calling getResultSet() -- with no parameters ?"
If so, I'll try to answer this question alone and just remind you that a class can hold state as instance variables.
Therefore, you can keep the queryTerm you get in the constructor and the Statement you are creating as instance variables
(I'm just pointing out a solution for your particular concern, assuming I got it right, as storing a Statement as an instance variable is a... "second best" practice, so to speak)
Again, as Mohamed pointed out, there is a lot to reconsider about your code, but I'd say let's clarify them one at a time...