Calculate Haversine Distance in Java

The haversine formula is an equation important in navigation, giving great-circle distances between two points on a sphere from their longitudes and latitudes. It is a special case of a more general formula in spherical trigonometry, the law of haversines, relating the sides and angles of spherical triangle

The hav­er­sine formula is used to cal­cu­late the dis­tance between two points on the Earth’s surface spe­cified in lon­gitude and latitude. It is a special case of a more general formula in spherical trigonometry, the law of haversines, relating the sides and angles of spherical "triangles".

d is the dis­tance between two points with lon­gitude and lat­itude (ψ,φ) and r is the radius of the Earth.

public class HaversineDistance {

public static double haversineDistance(double lat1,double lat2,double lon1,double lon2) {

           double deltaLat = Math.toRadians(lat1 - lat2);

           double deltaLong = Math.toRadians(lon1 - lon2);

           double lat1R = Math.toRadians(lat1);

           double lat2R = Math.toRadians(lat2);

           double a = (Math.sin(deltaLat/2.0) * Math.sin(deltaLat/2.0)) +

                      (Math.sin(deltaLong/2.0) * Math.sin(deltaLong/2.0) *

                      Math.cos(lat1R) * Math.cos(lat2R));

           double c = 2.0*Math.atan2(Math.sqrt(a), Math.sqrt(1.0 - a));

           double d = 3959.0*c;

           return d;

         }

         public static void main(String[] args) {

           System.out.println(haversineDistance(21.7679,40.4230,78.8718,98.7372));

         }

}