Why this code doesn't work properly?

Question

This is an UI that makes a ball go down in a diagonal way, but the ball stays static; it seems something is not working adecuatedly with the threads. Could you please, tell me how to make the ball move?

https://code.sololearn.com/cEd16IG11o9J/#java

Answer 1

OK, I had already solved it. It wasn't moving because I hadn't created an instance of the Layout that I was working on, so the thread didn't have connection with the ball and the coordinates; but, I managed to solve it.

Updated code: https://code.sololearn.com/cEd16IG11o9J/#java

Unfortunately, I have now another problem and it is that every time I hit the button "¡Animate it!" it doesn´t create a new ball. Also, when I hit it twice the ball speeds up; As if the coordinates get accumulated in some way. Could you explain me please, why it's not creating a new one; why the ball's speed is incrementing and how to make it bounce within the limits of the frame?