Calculate Distance(In KM) between two Locations

Use this method to calculate distance between two location in Kilometers. Note that Location is combination of Latitude and Longitude.

double distance(double lat1, double lon1, double lat2, double lon2) {
    double theta = lon1 - lon2;
    double distance = Math.sin(degTorad(lat1))
            * Math.sin(degTorad(lat2))
            + Math.cos(degTorad(lat1))
            * Math.cos(degTorad(lat2))
            * Math.cos(degTorad(theta));
    distance = Math.acos(distance);
    distance = radToDeg(distance);
    distance = distance * 60 * 1.1515;
    return (distance);
}

double degTorad(double deg) {
    return (deg * Math.PI / 180.0);
}

double radToDeg(double rad) {
    return (rad * 180.0 / Math.PI);
}