You should have no problem creating the class you want. I use a similar class to return a connection when I need it. It uses somewhat of a singleton
pattern in that if there is already a connection, I just return it, otherwise I open a new connection.
If it is a standalone application this is a good idea. If this is for a web app, use a Connection Pool.
Major psuedo code:
Just make sure you are using static methods and objects in your class for the connection.
Now, about putting a ResultSet into an ArrayList. The answer to your question is yes:
But a good question for you is why do you need to do that?