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// A simple class to hold the ball definition

public class Ball
{
public int dir = 1;  // direction of travel
public double x=0;   // current X
public double y=0;   // current y
public int maxheight=100;  // Y limit
public int maxwidth=100;   // X limit
public double speed=.1;    // step size for X
public java.awt.Color color;  // color

public void step()
  {
  x+=dir * speed;   // move X to next spot
  if (x>maxwidth)   // bounce off left/right wall
    {
    x-=speed;
    dir=-dir;
    }
  else if (x<0)
    {
    x+=speed;
    dir=-dir;
    }
 // describe bouncing with a sine wave
  y=Math.abs(Math.sin(x)*maxheight);
  }
}