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

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