public void drawDashedLine(Graphics g,int x1,int y1,int x2,int y2,
                           double dashlength, double spacelength) {
  if((x1==x2)&&(y1==y2)) {
    g.drawLine(x1,y1,x2,y2);
    return;
    }
  double linelength=Math.sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
  double yincrement=(y2-y1)/(linelength/(dashlength+spacelength));
  double xincdashspace=(x2-x1)/(linelength/(dashlength+spacelength));
  double yincdashspace=(y2-y1)/(linelength/(dashlength+spacelength));
  double xincdash=(x2-x1)/(linelength/(dashlength));
  double yincdash=(y2-y1)/(linelength/(dashlength));
  int counter=0;
  for (double i=0;i<linelength-dashlength;i+=dashlength+spacelength){
      g.drawLine((int) (x1+xincdashspace*counter),
                 (int) (y1+yincdashspace*counter),
                 (int) (x1+xincdashspace*counter+xincdash),
                 (int) (y1+yincdashspace*counter+yincdash));
      counter++;
      }
  if ((dashlength+spacelength)*counter<=linelength)
     g.drawLine((int) (x1+xincdashspace*counter),
                (int) (y1+yincdashspace*counter),
                x2,y2);
}