Please provide explanation for the following code:
public void travel(double dt)
{
  for (int i = 0; i < Arr.size(); i++)
  Arr.getBallAt(i).collision(cueBall);

  cueBall.travel(dt);

  for (int i = 0; i < Arr.size(); i++)
  Arr.getBallAt(i).travel(dt);//ball.AI(dt);

  for (int i = 0; i < Arr.size(); i++)
  ballMoved = cueBall.check(Arr.getBallAt(i));

  repaint();
}