//Override the paint() method
   public void paint(Graphics g){
    //Downcast the Graphics object to a
    // Graphics2D object
    Graphics2D g2 = (Graphics2D)g;
     
    //Scale device space to produce inches on
    // the screen
    // based on actual screen resolution.
    g2.scale((double)res/72,(double)res/72);
  
    //Translate origin to center of Frame
    g2.translate((hSize/2)*ds,(vSize/2)*ds);
     
    //Draw x-axis
    g2.draw(new Line2D.Double(
                               -1.5*ds,0.0,1.5*ds,0.0));
    //Draw y-axis
    g2.draw(new Line2D.Double(
                               0.0,-1.5*ds,0.0,1.5*ds));

Figure 1