How to get last location on Glass reliably?

Question

Method getLastLocation() from LocationManager often return null and it's quite tricky to select best provider. The documentation says:

Warning: Do not use the LocationManager.getBestProvider() method or the constants GPS_PROVIDER or NETWORK_PROVIDER to listen for location updates. Glass uses a dynamic set of providers and listening only to a single provider may cause your application to miss location updates.

How to get best last location?

Answer 1

Because Glass uses dynamic set of providers, you need to get location from all of them and select the location with best accuracy:

 public static Location getLastLocation(Context context) {
      LocationManager manager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
      Criteria criteria = new Criteria();
      criteria.setAccuracy(Criteria.NO_REQUIREMENT);
      List<String> providers = manager.getProviders(criteria, true);
      List<Location> locations = new ArrayList<Location>();
      for (String provider : providers) {
           Location location = manager.getLastKnownLocation(provider);
           if (location != null && location.getAccuracy()!=0.0) {
               locations.add(location);
           }
      }
      Collections.sort(locations, new Comparator<Location>() {
          @Override
          public int compare(Location location, Location location2) {
              return (int) (location.getAccuracy() - location2.getAccuracy());
          }
      });
      if (locations.size() > 0) {
          return locations.get(0);
      }
      return null;
 }