Bouncing Circles

Hi,

I want to bounce multiple circles off the Boundaries of an applet.
Till now, I have been able to do only one bouncing circle, whose x and y coordinate are explicitly specified in the program.
I want to add the circles from an arrayList.
Do i have to have multiple threads for such a program ie one thread for one circle?

Any help or tutorial on the same?

Thanks!

How is this different from your previous thread Moving Circles?

You have already been asked once before to Use One Thread Per Question.