I'm not sure about your approach to connect to DB (I really haven't tried it myself). But I suggest you to use DriverManager (for standalone applications) to get the connection to the DB, which is the preferred method. Check the JDBC tutorial
Line 19 is "Statement st = con.createStatement();" which can only mean that "con" is null. That means that d.connect("jdbc:oracle:thin:@oracle:8080:STUDENTINFO",p) returns null, which in turn means the URL is wrong.
I second Vijitha's advice to use DriverManager: If there's a problem this will throw an SQLException instead of returning null.