on the line you declare the con variable explicitly give the whole lot: java.sql.connection (getting the case correct).
and the same for driver mananger java.sql.DriverManager.
Just to see if somehow you are not using the classes you expect to be.
It does look like you have another Connection class in the same package. Possibly a compiled version that's hanging around even if you've deleted the source code. If you examined what Connection.class referred to it would confirm it.