Calcular distancia, expresada en KM, entre dos coordenadas GPS

ProjectHelpers.java

package com.benetjoandarder.helpers

import java.text.DecimalFormat;

public class ProjectHelpers {
    public static double calcDist(double lat1, double lon1, double lat2, double lon2){
        DecimalFormat df = new DecimalFormat("#.###");
        double R     = 6378.137;//Radio de la tierra en km
        double dLat  = Math.toRadians(lat2-lat1);
        double dLong = Math.toRadians(lon2-lon1);
        double a = Math.sin(dLat/2) * Math.sin(dLat/2) + Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) * Math.sin(dLong/2) * Math.sin(dLong/2);
        double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
        return R * c;
    }
}