public int count(@NonNull final Collection<? extends ICoordinate> points) {
        int total = 0;
        for (final ICoordinate point : points) {
            if (point != null && contains(point)) {
                total += 1;
            }
        }
        return total;
    }
Count the number of points present in the viewport.

@param points a collection of (possibly null) points
@return the number of non-null points in the viewport
main/src/main/java/cgeo/geocaching/location/Viewport.java