GPS-time in Android

Question

I'm looking for a way to display GPS-time in my app. What is the easiest way to do this?

(It has to be GPS-time due to slight time differences between gps time and internal system time)

Thanks

Answer 1

Getting the GPS time can be rather confusing! To extend discussions in accepted answer, getTime() in onLocationChanged() callback gives different answers depending on how the location (not necessarily GPS) information is retrieved, (based on Nexus 5 testing):

(a) If using Google FusedLocationProviderApi (Google Location Services API) then getProvider() will return 'fused' and getTime() will return devices time (System.currentTimeMillis())

(b) If using Android LocationManager (Android Location API), then, depending on the phone's 'location' settings and requestLocationUpdates settings (LocationManager.NETWORK_PROVIDER and/or LocationManager.GPS_PROVIDER), getProvider() will return:

• Either 'network', in which case getTime() will return the devices time (System.currentTimeMillis()).
• Or, 'gps', in which case getTime will return the GPS (satellite) time.

Essentially: 'fused' uses GPS & Wi-Fi/Network, 'network' uses Wi-Fi/Network, 'gps' uses GPS.

Thus, to obtain GPS time, use the Android LocationManager with requestLocationUpdates set to LocationManager.GPS_PROVIDER. (Note in this case the getTime() milliseconds part is always 000)

Here is an example using Android LocationManager (Android Location API):

public void InitialiseLocationListener(android.content.Context context) {

    android.location.LocationManager locationManager = (android.location.LocationManager)
            context.getSystemService(android.content.Context.LOCATION_SERVICE);

    android.location.LocationListener locationListener = new android.location.LocationListener() {

        public void onLocationChanged(android.location.Location location) {

            String time = new java.text.SimpleDateFormat("dd/MM/yyyy HH:mm:ss.SSS").format(location.getTime());

            if( location.getProvider().equals(android.location.LocationManager.GPS_PROVIDER))
                android.util.Log.d("Location", "Time GPS: " + time); // This is what we want!
            else
                android.util.Log.d("Location", "Time Device (" + location.getProvider() + "): " + time);
        }

        public void onStatusChanged(String provider, int status, android.os.Bundle extras) {
        }
        public void onProviderEnabled(String provider) {
        }
        public void onProviderDisabled(String provider) {
        }
    };

    if (android.support.v4.content.ContextCompat.checkSelfPermission(context,
            android.Manifest.permission.ACCESS_FINE_LOCATION) != android.content.pm.PackageManager.PERMISSION_GRANTED) {
        android.util.Log.d("Location", "Incorrect 'uses-permission', requires 'ACCESS_FINE_LOCATION'");
        return;
    }

    locationManager.requestLocationUpdates(android.location.LocationManager.NETWORK_PROVIDER, 1000, 0, locationListener);
    locationManager.requestLocationUpdates(android.location.LocationManager.GPS_PROVIDER, 1000, 0, locationListener);
    // Note: To Stop listening use: locationManager.removeUpdates(locationListener)
}