@@ -0,0 +1,1182 @@
+import java.util.*;%0A%0Apublic class Exercise7%0A%7B%0A%09public static void main(String%5B%5D args)%0A%09%7B%0A        Random random = new Random();%0A%09%09GameArena a;%0A        Ball balls%5B%5D;%0A        int ballCount;%0A        int maxSpeed = 5;%0A       %0A        try%0A        %7B%0A            ballCount = Integer.parseInt(args%5B0%5D);%0A            balls = new Ball%5BballCount%5D;%0A            %0A        %7D%0A        catch (Exception e)%0A        %7B%0A            System.out.println(%22%5CnUsage: java Exercise7 %3Cnumber_of_balls%3E%5Cn%5Cn%22);        %0A            return;%0A        %7D%0A%0A        a = new GameArena(1000,800);%0A%0A        for (int i=0; i%3Cballs.length; i++)%0A        %7B%0A            double x = random.nextDouble() * a.getArenaWidth();%0A            double y = random.nextDouble() * a.getArenaHeight();%0A            double s1 = maxSpeed - random.nextDouble()*maxSpeed*2;%0A            double s2 = maxSpeed - random.nextDouble()*maxSpeed*2;%0A%0A%09%09    balls%5Bi%5D = new Ball(x, y, 2, %22#FF0000%22);%0A            balls%5Bi%5D.setXSpeed(s1);%0A            balls%5Bi%5D.setYSpeed(s2);%0A%0A%09%09    a.addBall(balls%5Bi%5D);%0A        %7D%0A%0A%09%09while(true)%0A%09%09%7B%0A            for (int i=0; i%3Cballs.length; i++)%0A%09%09%09    balls%5Bi%5D.gravity(a.getArenaWidth(), a.getArenaHeight());%0A%0A%09%09%09a.pause();%0A%09%09%7D%0A%09%7D%0A%7D%0A

Add sample that to enable scalability testing