I am trying to build a program that shows about 10 randomly moving objects and I have written this code but it ends up in error on the fly method:

2. import java.util.Random;
3. 
   
4. Plane p;
5. 
   
6. void setup()
7. {
8.   size(600, 600);
9.   smooth();
10.   background(255);
11.   Plane p = new Plane();
12. }
13. 
    
14. void draw() {
15.   background(255);
16.   noStroke();
17.   fill(255,10);
18.   p.fly();
19. }
20. 
    
21. public class Plane
22. {
23.   float x;
24.   float y;
25.   float xspeed;
26.   float yspeed;
27.   
28.   public Plane()
29.   {
30.     Random generator = new Random();
31.     x = generator.nextInt(601);
32.     y = generator.nextInt(601);
33.     
34.     Double xsd = new Double(generator.nextDouble() / 5 + 0.01);
35.     Double ysd = new Double(generator.nextDouble() / 5 + 0.01);
36.     //System.out.println(xsd);
37.     //System.out.println(ysd);
38.     xspeed = xsd.floatValue();
39.     yspeed = ysd.floatValue();
40.   }  
41.   
42.   public void fly()
43.   {
44.     x += xspeed;
45.     y += yspeed;
46.   
47.     // Check for bouncing
48.     if ((x > width) || (x < 0)) {
49.       xspeed = xspeed * -1;
50.     }
51.     if ((y > height) || (y < 0)) {
52.       yspeed = yspeed * -1;
53.       
54.     }
55.     
56.         // Display at x,y location
57.     stroke(0);
58.     fill(175);
59.     ellipse(x,y,16,16);
60.   }
61.  
62. }

What's the problem?