Take a look at the following threads:
https://forum.processing.org/topic/how-to-get-this-class-code-work
and
https://forum.processing.org/topic/having-trouble-getting-various-things-to-happen-in-my-program-deals-with-constructors-changing-object-direction-when-it-bounces-and-1-more
from students in the same class than you...
I admit that with such great subject lines (like your*), they weren't easy to find in the list of recent threads.
One of them was even deleted by the owner, after I answered, which is rude. (But I have resurrection powers!)

* You are in a forum where most people just want help. The fact the URL of your message got a date shows you are not the first one to come up with this great subject line... Imagine if half of the messages in the Programming Questions had such kind of subject. A nightmare to find back a topic by glancing at the list...
The worst is that recently there is a surge of such titles void of information on the underlying topic.

Hey PhiLho !

Thanks a lot for the help ! You are awesome !