HaversineFormula.java

public class HaversineFormula {

    static double lat1, lat2, deg;

    public HaversineFormula() {}

    public static double calculate(double initialLat, double initialLong, double finalLat, double finalLong){

        int R = 6371; // km
        double dLat = toRadians(finalLat - initialLat);
        double dLon = toRadians(finalLong - initialLong);
        lat1 = toRadians(lat1);
        lat2 = toRadians(lat2);

        double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
                Math.sin(dLon/2) * Math.sin(dLon/2) * Math.cos(lat1) * Math.cos(lat2);
        double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
        return (int) Math.round((R * c) * 100)/(double) 100;
    }

    public static double toRadians(double deg) {
        return deg * (Math.PI/180);
    }
}