Intro

Recently I developed an application for Android that used reverse geocoding, ie. get a human readable address from a latitude/longitude position. To test what position i got for different location and to test what addresses that translated to i developed this little neat application.

Application info and download

Application to test Positioning and Reverse geocoding (Address from lat/lng). Optionally Save results to sdcard.

Download application (.apk)

Download source-code (.rar)

Explanation of code

Permissions

First off, we need to add the needed permissions to AndroidManifest.xml

The permissions are for; accessing internet which is used by the geocoder, using GPS and Network location, and writing files to SD-card.

Get user location

Getting the location of the user is done with the LocationManager and LocationListener. Start with getting in instance of the LocationManager.

locationManager = (LocationManager)
        this.getSystemService(Context.LOCATION_SERVICE);

Then I start requesting location updates, we also supply which listener that will handle location events.

locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,
        0, 0, locationListener);
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,
        0, 0, locationListener);

The listener i'm using is very simple and looks like this:

LocationListener locationListener = new LocationListener() {
  public void onLocationChanged(Location location) {
    txt_lat.setText("" + location.getLatitude());
    txt_lng.setText("" + location.getLongitude());
  }
  public void onStatusChanged(String provider, int status, Bundle extras) {}
  public void onProviderEnabled(String provider) {}
  public void onProviderDisabled(String provider) {}
};

Reverse geocoding

Now when we have a lat/lng position, either from a location update or manually inputed in the text boxes, its time to do some reverse geocoding. This is done with the Geocoder class, and looks like this:

Geocoder myLocation = new Geocoder(getApplicationContext(), Locale.getDefault());
List<Address> geo_adresses = myLocation.getFromLocation(lat, lng, 1);

now check if there was a resulting address, in that case get it. And in this application I wanted to see all different address fields that returned.

if(geo_adresses.size()>0){
  Address add = geo_adresses.get(0);
  for(int i = 0; i <= add.getMaxAddressLineIndex(); ++i){
    sb.append("AdressLine" + i + ": " + add.getAddressLine(i)+ "\n");
  }
  sb.append("AddminArea: "+ add.getAdminArea()+ "\n");
  sb.append("CoutryName: "+ add.getCountryName()+ "\n");
  sb.append("Premises: "+ add.getPremises()+ "\n");
  sb.append("SubAdminArea: "+ add.getSubAdminArea()+ "\n");
  sb.append("SubLocality: "+ add.getSubLocality()+ "\n");
  sb.append("Thoroughfare: "+ add.getThoroughfare()+ "\n");
  sb.append("SubThoroughfare: "+ add.getSubThoroughfare()+ "\n");

  txt_out.setText(sb.toString());
}

Conclusion

I found this little application very handy to test situations that don't occur during testing at home/office or with the emulator, to see what values you can expect to get from users when the application is live.