GeoUtil.java

public class GeoUtil {

  public static double distance(double lat1, double lon1, double lat2, double lon2, char unit) {
    double theta = lon1 - lon2;
    double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2))
        + Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * Math.cos(deg2rad(theta));
    dist = Math.acos(dist);
    dist = rad2deg(dist);
    dist = dist * 60 * 1.1515;
    if (unit == 'K') {
      dist = dist * 1.609344;
    } else if (unit == 'N') {
      dist = dist * 0.8684;
    }
    return (dist);
  }

  private static double deg2rad(double deg) {
    return (deg * Math.PI / 180.0);
  }

  private static double rad2deg(double rad) {
    return (rad * 180.0 / Math.PI);
  }
}