我的Runnable自定义视图动画将无法启动。

I've been assigned to make a simple android app game in which the user controls a ball on the screen by tilting the phone. The app utilizes a custom view to draw all the objects and it uses a Runnable object to animate the ball. Note that x and y represent the ball's postilion, vx and vy represent the ball's velocity and fx and fy represent the forces being applied to it. ix and iy represent the phone's tilt; I set these two to dummy values in order to test the app without worrying about setting up the sensor manager for the time being : I've been assigned to make a simple android app