Android activate gps with AlertDialog: how to wait for the user to take action?

Question

I've read different posts that there is no way to wait for the user to take an action when an AlertDialog is shown because it blocks the UI.

However, apps like Facebook for example displays the Gps is currently disabled. Do you want to enable gps? alert dialog and wait for the user to press yes/no. I'm thinking that it's possible to use 2 different activities, first one containing only the gps alert dialog, but this doesn't seem right and definetely doens't seem the way facebook does this.

Can anyone tell me how can i achieve this?

This is my code:

       @Override
    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    InitializeComponents();

    EnableGPSIfPossible();


        ListAsync lAsync = new ListAsync(this);
        lAsync .execute();
    }


    private void EnableGPSIfPossible()
{   
    final LocationManager manager = (LocationManager) getSystemService( Context.LOCATION_SERVICE );
     if ( !manager.isProviderEnabled( LocationManager.GPS_PROVIDER ) ) {
            buildAlertMessageNoGps();
        }
}

 private  void buildAlertMessageNoGps() {
        final AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setMessage("Yout GPS seems to be disabled, do you want to enable it?")
               .setCancelable(false)
               .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                   public void onClick(@SuppressWarnings("unused") final DialogInterface dialog, @SuppressWarnings("unused") final int id) {
                     startActivity(new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS));
                   }
               })
               .setNegativeButton("No", new DialogInterface.OnClickListener() {
                   public void onClick(final DialogInterface dialog, @SuppressWarnings("unused") final int id) {
                        dialog.cancel();
                   }
               });
        final AlertDialog alert = builder.create();
        alert.show();
    }

So, in my code the AsynTask starts imediately without waiting for the user to activate the gps. (which is a normal behaviour)

Thank you!

Answer 1

What you can actually do is this :

GPSManager.java :

public class GPSManager {

    private Activity activity;
    private LocationManager mlocManager;
    private LocationListener gpsListener;

    public GPSManager(Activity activity) {
        this.activity = activity;
    }

    public void start() {
        mlocManager = (LocationManager) activity
                .getSystemService(Context.LOCATION_SERVICE);

        if (mlocManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
            setUp();
            findLoc();
        } else {
            AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(
                    activity);
            alertDialogBuilder
                    .setMessage("GPS is disabled in your device. Enable it?")
                    .setCancelable(false)
                    .setPositiveButton("Enable GPS",
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog,
                                        int id) {
                                    Intent callGPSSettingIntent = new Intent(
                                            android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                                    activity.startActivity(callGPSSettingIntent);
                                }
                            });
            alertDialogBuilder.setNegativeButton("Cancel",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            dialog.cancel();
                        }
                    });
            AlertDialog alert = alertDialogBuilder.create();
            alert.show();

        }
    }

    public void setUp() {
        gpsListener = new GPSListener(activity, mlocManager);
    }

    public void findLoc() {
        mlocManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1, 1,
                gpsListener);

        if (mlocManager.getLastKnownLocation(LocationManager.GPS_PROVIDER) == null)
            Toast.makeText(activity, "LAST Location null", Toast.LENGTH_SHORT)
                    .show();
        else {
            gpsListener.onLocationChanged(mlocManager
                    .getLastKnownLocation(LocationManager.GPS_PROVIDER));
        }
    }
}

GPSListener.java :

public class GPSListener implements LocationListener {

    private Activity activity;
    private LocationManager lm;
    private int numberOfUpdates;

    public static final int MAX_NUMBER_OF_UPDATES = 10;

    public GPSListener(Activity activity, LocationManager lm) {
        this.activity = activity;
        this.lm = lm;
    }

    @Override
    public void onLocationChanged(Location loc) {
        if (numberOfUpdates < MAX_NUMBER_OF_UPDATES) {
            numberOfUpdates++;

            Log.w("LAT", String.valueOf(loc.getLatitude()));
            Log.w("LONG", String.valueOf(loc.getLongitude()));
            Log.w("ACCURACY", String.valueOf(loc.getAccuracy() + " m"));
            Log.w("PROVIDER", String.valueOf(loc.getProvider()));
            Log.w("SPEED", String.valueOf(loc.getSpeed() + " m/s"));
            Log.w("ALTITUDE", String.valueOf(loc.getAltitude()));
            Log.w("BEARING", String.valueOf(loc.getBearing() + " degrees east of true north"));

            String message;

            if (loc != null) {
                message = "Current location is:  Latitude = "
                        + loc.getLatitude() + ", Longitude = "
                        + loc.getLongitude();
                // lm.removeUpdates(this);
            } else
                message = "Location null";

            Toast.makeText(activity, message, Toast.LENGTH_SHORT).show();
        } else {
            lm.removeUpdates(this);
        }
    }

    @Override
    public void onProviderDisabled(String provider) {
        Toast.makeText(activity, "Gps Disabled", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onProviderEnabled(String provider) {
        Toast.makeText(activity, "Gps Enabled", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {

    }

}

And then from your activity :

GPSManager gps = new GPSManager(
                                    yourActivity.this);
                            gps.start();

Answer 2

I done that by using simple function but without displaying an alert box i redirected usercontrol to setting page

Here is the function i used

public void isGPSEnable(){
        LocationManager service = (LocationManager) getSystemService(LOCATION_SERVICE);
        boolean enabled = service
          .isProviderEnabled(LocationManager.GPS_PROVIDER);
        if (!enabled) {
          Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
          startActivity(intent);
        } 

}

Answer 3

I managed to get this to work.I got inspired by this article here which i found on stackoverlfow. http://developmentality.wordpress.com/2009/10/31/android-dialog-box-tutorial/

I basically moved the logic that i needed to execute on the "Yes" and "Cancel" buttons of the alert Dialog. After performing logic needed for Yes and Cancel buttons i start the asyncronous logic execution.

Here's my code:

public interface ICommand
{
    void execute();
}

The two concrete Commands used for Enable Gps and Cancel buttons of the alert Dialog:

public class CancelCommand implements ICommand
{
    protected Activity m_activity;

    public CancelCommand(Activity activity)
    {
        m_activity = activity;
    }

    public void execute()
    {
        dialog.dismiss();
        //start asyncronous operation here
    }
}


public class EnableGpsCommand extends CancelCommand
{
    public EnableGpsCommand( Activity activity) {
        super(activity);
    }

    public void execute()
    {
        // take the user to the phone gps settings and then start the asyncronous logic.
        m_activity.startActivity(new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS));
        super.execute();
    }
}

And now, from the Activity:

//returns true if the GpsProviderIsDisabled
//false otherwise
private boolean EnableGPSIfPossible()
{   
    final LocationManager manager = (LocationManager) getSystemService( Context.LOCATION_SERVICE );
    if ( !manager.isProviderEnabled( LocationManager.GPS_PROVIDER ) ) {
        buildAlertMessageNoGps();
        return true;
    }
    return false;
}


private  void buildAlertMessageNoGps()
{
    final AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage("Yout GPS seems to be disabled, do you want to enable it?")
        .setCancelable(false)
        .setPositiveButton("Yes", new CommandWrapper(new EnableGpsCommand(this)))
        .setNegativeButton("No", new CommandWrapper(new CancelCommand(this))); 

    final AlertDialog alert = builder.create();
    alert.show();
}

Now from the Activity OnCreate methodi just call:

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.newfriendlist);

    InitializeComponents();

    if (!EnableGPSIfPossible())
    {
        //then gps is already enabled and we need to do StartFriendRetrievalAsync from here.
        //otherwise this code is being executed from the EnableGpsIfPossible() logic.


        //Asyncronous logic here.
    }
}

I really hope this will help you when you get stuck at this point :).

Cheers