LatLonDistanceCalculator.java

/**
 * This helper is used to calculate the distance between two Latitude/Longitude points in kilometers.
 */
public class LatLonDistanceCalculator {

    private static final int EARTH_RADIUS_IN_KILOMETERS = 6371;

    public static float calculateDistance(Point pointA, 
                                          Point pointB) {

        double dLat = Math.toRadians(pointB.getLatitude()
                - pointA.getLatitude());

        double dLng = Math.toRadians(pointB.getLongitude()
                - pointA.getLongitude());

        double a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
                Math.cos(Math.toRadians(pointA.getLatitude())) *
                Math.cos(Math.toRadians(pointB.getLatitude())) *
                Math.sin(dLng / 2) * Math.sin(dLng / 2);

        double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));

        return (float) (EARTH_RADIUS_IN_KILOMETERS * c);
    }

}