Get the last known location

Using the Google Play services location APIs, your app can request the last known location of the user's device. In most cases, you are interested in the user's current location, which is usually equivalent to the last known location of the device.

Specifically, use the fused location provider to retrieve the device's last known location. The fused location provider is one of the location APIs in Google Play services. It manages the underlying location technology and provides a simple API so that you can specify requirements at a high level, like high accuracy or low power. It also optimizes the device's use of battery power.

This lesson shows you how to make a single request for the location of a device using the getLastLocation() method in the fused location provider.

Set up Google Play services

To access the fused location provider, your app's development project must include Google Play services. Download and install the Google Play services component via the SDK Manager and add the library to your project. For details, see the guide to Setting Up Google Play Services.

Specify app permissions

Apps whose features use location services must request location permissions, depending on the use cases of those features.

Create location services client

In your activity's onCreate() method, create an instance of the Fused Location Provider Client as the following code snippet shows.

private lateinit var fusedLocationClient: FusedLocationProviderClient

override fun onCreate(savedInstanceState: Bundle?) {
    // ...

    fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
}

private FusedLocationProviderClient fusedLocationClient;

// ..

@Override
protected void onCreate(Bundle savedInstanceState) {
    // ...

    fusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
}

Get the last known location

Once you have created the Location Services client you can get the last known location of a user's device. When your app is connected to these you can use the fused location provider's getLastLocation() method to retrieve the device location. The precision of the location returned by this call is determined by the permission setting you put in your app manifest, as described in the guide on how to request location permissions.

To request the last known location, call the getLastLocation() method. The following code snippet illustrates the request and a simple handling of the response:

fusedLocationClient.lastLocation
        .addOnSuccessListener { location : Location? ->
            // Got last known location. In some rare situations this can be null.
        }

fusedLocationClient.getLastLocation()
        .addOnSuccessListener(this, new OnSuccessListener<Location>() {
            @Override
            public void onSuccess(Location location) {
                // Got last known location. In some rare situations this can be null.
                if (location != null) {
                    // Logic to handle location object
                }
            }
        });

The getLastLocation() method returns a Task that you can use to get a Location object with the latitude and longitude coordinates of a geographic location. The location object may be null in the following situations:

• Location is turned off in the device settings. The result could be null even if the last location was previously retrieved because disabling location also clears the cache.
• The device never recorded its location, which could be the case of a new device or a device that has been restored to factory settings.
• Google Play services on the device has restarted, and there is no active Fused Location Provider client that has requested location after the services restarted. To avoid this situation you can create a new client and request location updates yourself. For more information, see Receiving Location Updates.

Maintain a current best estimate

You might expect the Location object that's contained in the most recent call to getLastLocation() to be the most accurate. However, because the accuracy of a location varies, the most recent value isn't necessarily the best. You should include logic for choosing which location to show based on several criteria. The set of criteria also varies, depending on the use cases of your app and results from field testing.

To validate the accuracy of a location that's returned from getLastLocation(), complete steps that include the following:

• Check whether the location retrieved is significantly newer than the previously fetched location.
• Check whether the accuracy claimed by the location is better or worse than that of the previous estimate.
• Check the provider that's associated with the new location. Decide whether you trust this provider more than the one used in your app's cached location.