Try something like this
            Geocoder geoCoder = new Geocoder(
                getBaseContext(), Locale.getDefault());
            try {
                List<Address> addresses = geoCoder.getFromLocation(
                    srcGeoPoint.getLatitudeE6()  / 1E6, 
                    srcGeoPoint.getLongitudeE6() / 1E6, 1);
                String add = "";
                if (addresses.size() > 0) 
                {
                    for (int i=0; i<addresses.get(0).getMaxAddressLineIndex(); 
                         i++)
                       add += addresses.get(0).getAddressLine(i) + "\n";
                }
                Toast.makeText(getBaseContext(), add, Toast.LENGTH_SHORT).show();
            } catch (IOException e) {                
                e.printStackTrace();
            }   
taken from: http://mobiforge.com/developing/story/using-google-maps-android
see geocoding and reverse geocoding about halfway down the page
you might also want to look at  https://developers.google.com/maps/documentation/geocoding/