public static double CalculateArea (List<Point> pointList)
    {
        double area = 0;
        int n = pointList.size() - 1;
        Point a = pointList.get(0);
        pointList.add(a);
        for(int i = 0; i<n; i++)
        {
           area+= 0.5(pointList.get(i).getX()pointList.get(i+1).getY() - pointList.get(i+1).getX()*pointList.get(i).getY());
        }
        return Math.abs(area);

    }