android - LocationClient getLastLocation() return null

Question

Like the questions someone encountered before I tested one the nexus s(4.0.4 with google play service available) and avd (4.2.2 with google api), in both case locationclient's getLastLocation() always return null.

public class MainActivity extends Activity implements LocationListener,
        GooglePlayServicesClient.ConnectionCallbacks,
        GooglePlayServicesClient.OnConnectionFailedListener {

    private LocationClient mLocationClient;
    private LocationRequest mLocationRequest;
    boolean mUpdatesRequested = false;
    boolean mConnected = false;
    SharedPreferences mPrefs;
    SharedPreferences.Editor mEditor;
    private TextView mText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mText = (TextView) findViewById(R.id.text);
        mLocationRequest = LocationRequest.create();
        mLocationRequest
                .setInterval(LocationUtils.UPDATE_INTERVAL_IN_MILLISECONDS);
    mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        mLocationRequest
.setFastestInterval(LocationUtils.FAST_INTERVAL_CEILING_IN_MILLISECONDS);
        mUpdatesRequested = false;
        mPrefs = getSharedPreferences(LocationUtils.SHARED_PREFERENCES,
                Context.MODE_PRIVATE);
        mEditor = mPrefs.edit();
        mLocationClient = new LocationClient(this, this, this);
    }
    @Override
    public void onStart() {
        super.onStart();
        /*
         * Connect the client. Don't re-start any requests here; instead, wait
         * for onResume()
         */
        mLocationClient.connect();
    }

    @Override
    protected void onResume() {
        super.onResume();
        // If the app already has a setting for getting location updates, get it
        if (mPrefs.contains(LocationUtils.KEY_UPDATES_REQUESTED)) {
            mUpdatesRequested = mPrefs.getBoolean(
                    LocationUtils.KEY_UPDATES_REQUESTED, false);
            // Otherwise, turn off location updates until requested
        } else {
            mEditor.putBoolean(LocationUtils.KEY_UPDATES_REQUESTED, false);
            mEditor.commit();
        }
    }
    @Override
    public void onStop() {
        // If the client is connected
        if (mLocationClient.isConnected()) {
            stopPeriodicUpdates();
        }
        // After disconnect() is called, the client is considered "dead".
        mLocationClient.disconnect();
        super.onStop();
    }

    @Override
    public void onPause() {
        // Save the current setting for updates
        mEditor.putBoolean(LocationUtils.KEY_UPDATES_REQUESTED,
                mUpdatesRequested);
        mEditor.commit();
        super.onPause();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    public void getLocation(View v) {
        // If Google Play Services is available
        if (isGooglePlayServicesAvailable()) {
            if (!mConnected)
                mText.setText("location client is not connected to service yet");
            else {
                // Get the current location
                Location currentLocation = mLocationClient.getLastLocation();
                // Display the current location in the UI
                mText.setText(LocationUtils.getLocationString(currentLocation));
            }
        }
    }

    private boolean isGooglePlayServicesAvailable() {

        // Check that Google Play services is available
        int resultCode = GooglePlayServicesUtil
                .isGooglePlayServicesAvailable(this);

        // If Google Play services is available
        if (ConnectionResult.SUCCESS == resultCode) {
            // In debug mode, log the status
            Log.d(LocationUtils.APPTAG, "google play service is available");

            // Continue
            return true;
            // Google Play services was not available for some reason
        } else {
            // Display an error dialog
            Dialog dialog = GooglePlayServicesUtil.getErrorDialog(resultCode,
                    this, 0);
            if (dialog != null) {
                Log.e(LocationUtils.APPTAG,
                        "google play service is unavailable");
            }
            return false;
        }
    }

    private void stopPeriodicUpdates() {
        mLocationClient.removeLocationUpdates(this);
        // mConnectionState.setText(R.string.location_updates_stopped);
    }

    @Override
    public void onConnectionFailed(ConnectionResult arg0) {
        mConnected = false;
        Log.d(LocationUtils.APPTAG, "connection failed");
    }

    @Override
    public void onConnected(Bundle arg0) {
        mConnected = true;
        Log.d(LocationUtils.APPTAG,
                "location client connected to the location server");
        LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        lm.requestLocationUpdates(LocationManager.PASSIVE_PROVIDER, 0, 0,
                new android.location.LocationListener() {
                    @Override
                    public void onStatusChanged(String provider, int status,
                            Bundle extras) {}

                    @Override
                    public void onProviderEnabled(String provider) {}

                    @Override
                    public void onProviderDisabled(String provider) {}

                    @Override
                    public void onLocationChanged(final Location location) {
                    }
                });
        Log.d(LocationUtils.APPTAG, "done trying to get location");
    }

    @Override
    public void onDisconnected() {
        // TODO Auto-generated method stub
        mConnected = false;
        Log.d(LocationUtils.APPTAG,
                "location client disconnected from the location server");
    }

    @Override
    public void onLocationChanged(Location arg0) {}

}

most of them came from examples given by google. In the code above hava tried the method like that:

LocationRequest request = LocationRequest.create();
request.setNumUpdates(1);
mLocationClient.requestLocationUpdates(request, this);

and

LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

        lm.requestLocationUpdates(LocationManager.PASSIVE_PROVIDER, 0, 0,
                new android.location.LocationListener() {
                    @Override
                    public void onStatusChanged(String provider, int status,Bundle extras) {}

                    @Override
                    public void onProviderEnabled(String provider) {}

                    @Override
                    public void onProviderDisabled(String provider) {}

                    @Override
                    public void onLocationChanged(final Location location) {}
                });

In onConnected() before calling getLastLocation(), but still get no luck. Where's the mistake, Thanks in advance.

Answer 1

Currently the Fused Location Provider will only maintain background location if at least one client is connected to it. Once the first client connects, it will immediately try to get a location. If your activity is the first client to connect and you call getLastLocation() right away in onConnected(), that might not be enough time for the first location to come in.