android - Representing and comparing geographic locations in Java -

i'm trying figure out how represent geographic locations, , can't seem find relevant classes in se documentation.

i this:

location loca = new location(aa.aaaaaaa, bb.bbbbbbb); //lat/long coordinates location locb = ..... int meters = loca.distanceto(locb); 

ideally want android location since of location data sent android devices anyway. understanding contains information accuracy, latitude , speed, useful (but not required).

i have idea of how implement myself, open source alternative save me time.

it extremely helpful if ip/location lookup. guess that's whole other issue.

here method calculate distance between 2 points, taken android location class small modification. looks little bit complicated--this because uses vincenty's formulae perform iterative calculations on wgs84 ellipsoid:

/** distance between 2 geographic points on earth, in km **/ public static double geodistance(geopoint gp1, geopoint gp2) {         // based on http://www.ngs.noaa.gov/pubs_lib/inverse.pdf         // using "inverse formula" (section 4)          int maxiters = 20;         // convert lat/long radians         double lat1 = gp1.getlat() * math.pi / 180.0;         double lat2 = gp2.getlat() * math.pi / 180.0;         double lon1 = gp1.getlon() * math.pi / 180.0;         double lon2 = gp2.getlon() * math.pi / 180.0;          double = 6378.137; // wgs84 major axis         double b = 6356.7523142; // wgs84 semi-major axis         double f = (a - b) / a;         double asqminusbsqoverbsq = (a * - b * b) / (b * b);          double l = lon2 - lon1;         double = 0.0;         double u1 = math.atan((1.0 - f) * math.tan(lat1));         double u2 = math.atan((1.0 - f) * math.tan(lat2));          double cosu1 = math.cos(u1);         double cosu2 = math.cos(u2);         double sinu1 = math.sin(u1);         double sinu2 = math.sin(u2);         double cosu1cosu2 = cosu1 * cosu2;         double sinu1sinu2 = sinu1 * sinu2;          double sigma = 0.0;         double deltasigma = 0.0;         double cossqalpha = 0.0;         double cos2sm = 0.0;         double cossigma = 0.0;         double sinsigma = 0.0;         double coslambda = 0.0;         double sinlambda = 0.0;          double lambda = l; // initial guess         (int iter = 0; iter < maxiters; iter++) {             double lambdaorig = lambda;             coslambda = math.cos(lambda);             sinlambda = math.sin(lambda);             double t1 = cosu2 * sinlambda;             double t2 = cosu1 * sinu2 - sinu1 * cosu2 * coslambda;             double sinsqsigma = t1 * t1 + t2 * t2; // (14)             sinsigma = math.sqrt(sinsqsigma);             cossigma = sinu1sinu2 + cosu1cosu2 * coslambda; // (15)             sigma = math.atan2(sinsigma, cossigma); // (16)             double sinalpha = (sinsigma == 0) ? 0.0 :                 cosu1cosu2 * sinlambda / sinsigma; // (17)             cossqalpha = 1.0 - sinalpha * sinalpha;             cos2sm = (cossqalpha == 0) ? 0.0 :                 cossigma - 2.0 * sinu1sinu2 / cossqalpha; // (18)              double usquared = cossqalpha * asqminusbsqoverbsq; // defn             = 1 + (usquared / 16384.0) * // (3)                 (4096.0 + usquared *                  (-768 + usquared * (320.0 - 175.0 * usquared)));             double b = (usquared / 1024.0) * // (4)                 (256.0 + usquared *                  (-128.0 + usquared * (74.0 - 47.0 * usquared)));             double c = (f / 16.0) *                 cossqalpha *                 (4.0 + f * (4.0 - 3.0 * cossqalpha)); // (10)             double cos2smsq = cos2sm * cos2sm;             deltasigma = b * sinsigma * // (6)                 (cos2sm + (b / 4.0) *                  (cossigma * (-1.0 + 2.0 * cos2smsq) -                   (b / 6.0) * cos2sm *                   (-3.0 + 4.0 * sinsigma * sinsigma) *                   (-3.0 + 4.0 * cos2smsq)));              lambda = l +                 (1.0 - c) * f * sinalpha *                 (sigma + c * sinsigma *                  (cos2sm + c * cossigma *                   (-1.0 + 2.0 * cos2sm * cos2sm))); // (11)              double delta = (lambda - lambdaorig) / lambda;             if (math.abs(delta) < 1.0e-12) {                 break;             }         }          return b * * (sigma - deltasigma);     } 

geopoint class looks following:

/**  * immutable point in geo coordinates (latitude, longitude) accuracy in km  */ public class geopoint {      private final double lat;     private final double lon;     private final double accuracy;      /**      * new geo point without accuracy      */     public geopoint(double lat, double lon){         this(lat, lon, -1d);     }      /**      * new geo point specified accuracy      * @param accuracy  accuracy in km      */     public geopoint(double lat, double lon, double accuracy){         this.lat = lat;         this.lon = lon;         this.accuracy = accuracy < 0 ? -1d : accuracy;     }      public double getlat(){         return this.lat;     }      public double getlon(){         return this.lon;     }      /**      * @return accuracy in km. if < 0, accuracy not defined      */     public double getaccuracy(){         return this.accuracy;     }      @override     public string tostring(){         return "lat = " + this.lat + "; lon = " + this.lon + (this.accuracy < 0 ? "" : ("; accuracy = " + this.accuracy));     }      @override     public boolean equals(object o) {         if (this == o) return true;         if (!(o instanceof geopoint) || o == null) return false;         geopoint g = (geopoint) o;         return g.lat == this.lat && g.lon == this.lon && g.accuracy == this.accuracy;      }   }