This code will find the position of all contours.
List<Moments> mu = new ArrayList<Moments>(Contours.size());
for (int i = 0; i < Contours.size(); i++) {
mu.add(i, Imgproc.moments(Contours.get(i), false));
Moments p = mu.get(i);
int x = (int) (p.get_m10() / p.get_m00());
int y = (int) (p.get_m01() / p.get_m00());
Core.circle(rgbaImage, new Point(x, y), 4, new Scalar(255,49,0,255));
}