Having trouble painting object...

[MarcGerrish]

Hopefully someone will know why I can't get this to work properly, as I've been trying to suss it outy myself for the last four hours and am not getting anywhere.

It's a simple program to display two balls and a 'passage' (three rectangles at this stage) on a 'playingfield'

I know that the commands causing the runtine errors are the "blueball.paint(g)" "redball.paint(g)" and "thepassage.paint(g)" Everything else works fine.

Any ideas anyone?

*snip*

class ball
{
  Rectangle location;
  Color ballcolor=Color.blue;

  ball(int x, int y, int wh)
  {
    location=new Rectangle(x,y,wh,wh);
  }

  public void paint(Graphics g)
  {
    g.setColor(ballcolor);
    g.fillOval(location.x,location.y,location.width,location.height);
  }
}

*snip 'class passage' - same as 'class ball'

class field extends Frame implements Runnable
{
  Thread runner;
  ball blueball,redball;
  passage thepassage;
  int screenx=600;
  int screeny=400;
  int divx=20;
  int passagey=100;
  Color bgcolor=new Color(255,128,0);
  Color divcolor=Color.black;

  field()
  {
    super("Demon Balls");
    setSize(screenx,screeny);
    setBackground(bgcolor);
    ball blueball=new ball(100,175,50);
    ball redball=new ball(250,175,50);
    passage thepassage=new passage(((screenx-divx)/2),((screeny-passagey)/2),divx,passagey);
    show();
    runner=new Thread(this);
    runner.start();
  }

  public void drawbg(Graphics g)
  {
    g.setColor(bgcolor);
    g.drawRect(0,0,screenx,screeny);
    g.setColor(divcolor);
    g.fillRect(((screenx-divx)/2),0,divx,screeny);
  }

  public void paint(Graphics g)
  {
    drawbg(g);
    blueball.paint(g);
    redball.paint(g);
    thepassage.paint(g);
  }

  public void run()
  {
    repaint();
    try{Thread.sleep(500);}
    catch(InterruptedException e){}
  }
}

public class demonballs
{
  public static void main(String args[])
  {
    field playingfield;
    playingfield=new field();
    playingfield.show();
  }
}

 

[MarcGerrish]

The error message mentions a null pointer exception. I know what this means; attempting to access an object that doesn't exist, but as far as I can see blueball, redball and thepassage have all been declared correctly :-s