Develop Reference

Is phone using only GPS to get it's location?

I am conducting test where we are compering GPS position of Android phone and GPS device which we would like to integrate in our hardware. But for the test to be accurate, phone need to use only GPS and not cell towers and WiFi.
Here is the code, where I set which service does the phone use.
LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
locationManager
.requestLocationUpdates(LocationManager.GPS_PROVIDER,
MIN_MILLISECONDS_BEFORE_UPDATE_LOCATION,
MIN_METERS_BEFORE_UPDATE_LOCATION,
new MyLocationListener(this));
So will phone use only GPS to get it's location? I can' turn WIFI off, because phones are sending current locations to our data base. Both GPS device and phone are on a fixed location at the time of test.
I know that there are already questions how to use GPS for acquiring location, but I would like to make sure, that phone is using just GPS.

It can find location by only using GPS (Assuming that location is reachable, for example not underground or something like that) By using internet it just finds location faster. Since your device is stationary you should be ok.
Read more about it here.

default it use gps and if gps not working it will use internet so you dont need wright something
Use the LocationManager.
LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
Location location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
double longitude = location.getLongitude();
double latitude = location.getLatitude();
The call to getLastKnownLocation() doesn't block - which means it will return null if no position is currently available - so you probably want to have a look at passing a LocationListener to the requestLocationUpdates() method instead, which will give you asynchronous updates of your location.
private final LocationListener locationListener = new LocationListener() {
public void onLocationChanged(Location location) {
longitude = location.getLongitude();
latitude = location.getLatitude();
}
}
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 2000, 10, locationListener);
You'll need to give your application the ACCESS_FINE_LOCATION permission if you want to use GPS.
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
You may also want to add the ACCESS_COARSE_LOCATION permission for when GPS isn't available and select your location provider with the getBestProvider() method.

do I need to enable gps when using NETWORK_PROVIDER

I've written an android application that needs the user location, it was working fine when I used gps provider, but I don't want to use GPS because it uses a lot of battery, here is my code
LocationManager locaionManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,5*1000,0, new MyLocaionListener());
Location loco = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
Log.d("enabled=" ,"" + locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER));
This code returns a null Location Object, and the logCat shows enabled=false when the location service is disabled although I'm using NETWORK_PROVIDER But when I enable the location service from the phone settings I get enabled=true and I get my current location.
So my question is:
does network provider also uses the phone GPS? and how do GPS and NETWORK providers internally works.

Android get location from GPS

My situation is like that the user has their tablet with them all day and its gps or location can be turned off whole time to save battery, and then wanna post something using my application which requires them to turn on the location and then upon posting I wanna get the latitude and longitude of the device. Using LocationManager when I get the location its null. Any help would be appreciated.
I'm using the below code to get the location:
LocationManager lm = (LocationManager)ctx.getSystemService(Context.LOCATION_SERVICE);
Location location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
As I've checked around, it seems I have to put a listenere to update the device location so when I get the last known location it wouldn't be null, but how can I do that if the device's location is off before using the application? I wanna get the location where the user is posting using the application.
EDIT: I've changed my code to below, but loc is always null and loc2 always returns location. why is that?
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListener);
Location loc = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
Location loc2 = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
and this is the listener:
LocationListener locationListener = new LocationListener() {
public void onLocationChanged(Location location) {
}
public void onStatusChanged(String provider, int status, Bundle extras) {
}
public void onProviderEnabled(String provider) {
}
public void onProviderDisabled(String provider) {
}
};

You might want to consider using Network Location as well as GPS Location, as many users just keep the GPS radio off to conserve battery.
With Location Services set in "Battery Saving" mode, the device can get accurate geo-location data using Wi-Fi if available.
If you use Network Location data as well as GPS radio data, you would have a much better chance of getting location data when you need it.
However, if Location Services were disabled completely prior to being turned on in order to post something using your app, then you would need to register a Location Listener to get the first instance of location data.
Take a look at this post to see how to use both Network and GPS Location:
Android Location Manager, Get GPS location ,if no GPS then get to Network Provider location

GPS rarely works indoors. If your users are "visiting shops" then it makes sense the GPS provider will never return a valid location as there is no GPS signal available indoors.
The network provider uses both Wifi and cell towers, so as long as they at least have cell service, you should return a location. That explains why you are always able to retrieve a location update with the network provider.
I would recommend you look into the Fused Provider which is the newest Location API released by Google. This API will automatically handle switching between GPS, network, and passive location listeners for you based on both what settings the user has enabled and which provider gives the best data given the users situation.

Android Fall back to ACCURACY_COARSE if GPS in not available

I am using the Criteria object to get the best provider like so
final boolean isGpsEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
if(isGpsEnabled) {
Criteria crit = new Criteria();
crit.setAccuracy(Criteria.ACCURACY_FINE);
crit.setCostAllowed(true);
crit.setPowerRequirement(Criteria.NO_REQUIREMENT);
crit.setSpeedRequirement(false);
String provider = locationManager.getBestProvider(criteria, true);
locationManager.requestLocationUpdates(provider, 600000, 0, new myLocationListener());
}
On my phone (Android 4.1) I have both "Use GPS Satellites" and "Use Wireless Networks" options enabled. Now, the above code works great when I am outdoors and it gives me the GPS location.
But, when I am indoors it does not revert to the "network" provider. It just keeps trying to get the location via GPS and never get its (I wait 1 minute or so)
When I change the code of Criteria to use Criteria.ACCURACY_COARSE then it uses "network" provider.
How do I get it to first try the GPS (because it is enabled) and because we are indoor it will not be able to connect to a satellite to then fall back to using the "network". I can't get that working easily. I state again, GPS is enabled but no access to satellites so want it to get network location instead.
Thanks.

The solution was create the location manager and attach 2 listeners to receive updates. One for GPS and another for NETWORK. You set it to receive updates fairly quickly (or depending on your own case, I just needed to get the location) You then create a method that compares the location of the GPS and Network and find which one is more accurate. You do this at most 3 times to get on average which one is returning the most accurate position and then you stop the location updates.

What happens if Android device does not have GPS as a location provider

Given this code
if (!locator.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
//consider forcing user to turn on gps here
} else {
provider = LocationManager.GPS_PROVIDER;
}
What happens if the device does not have GPS. Right now if that provider isn't enabled then it I will jump the user to their system settings to turn it on. But what if it isn't there? How would this be handled. I dont want to necessarily lock those kind of users out of the app.

If the GPS provider is not available (or enabled), then try for whatever you can get:
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_HIGH);
criteria.setPowerRequirement(Criteria.POWER_HIGH);
LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
String provider = lm.getBestProvider(criteria, true);
This assumes that you prefer a rough position over no position at all.

You only need the GPS if you want precise locations. If the device simply does not have a GPS, then you can estimate with less accuracy through the NETWORK_PROVIDER. That's usually suitable if you just need the general location of a user (west side of a city, near a memorial, etc.). If you absolutely need a specific location that's within a specific accuracy for your app to work, then you're user without GPS is just out of luck.
Alternatively, if you enable GPS and the user doesn't have GPS, it simply won't get updates. In that case, you'll have to mention that the updates aren't precise because of lack of GPS, and the user will have to use a weaker version of your app.