get distance from latitude and longitude code android

1private double distance(double lat1, double lon1, double lat2, double lon2) {
2    double theta = lon1 - lon2;
3    double dist = Math.sin(deg2rad(lat1)) 
4                    * Math.sin(deg2rad(lat2))
5                    + Math.cos(deg2rad(lat1))
6                    * Math.cos(deg2rad(lat2))
7                    * Math.cos(deg2rad(theta));
8    dist = Math.acos(dist);
9    dist = rad2deg(dist);
10    dist = dist * 60 * 1.1515;
11    return (dist);
12}
13
14private double deg2rad(double deg) {
15    return (deg * Math.PI / 180.0);
16}
17
18private double rad2deg(double rad) {
19    return (rad * 180.0 / Math.PI);
20}
21