Class example -i don't understand the error

[Larz60+]

The professor must be a java programmer, as stated by Ichabod very poor example.
Since you say it's an assignment, the hints provided above should give you a clue so that you can finish the assignment.
trace out what a1 and a2's role are in the code.
There is also more than one way to answer, as you can add another attribute to SuperClass, or remove on from testObject