public static synchronized void setMapSource(final MapSource newMapSource) {
        if (newMapSource != null && newMapSource.isAvailable()) {
            putString(R.string.pref_mapsource, newMapSource.getId());
            // cache the value
            mapSource = newMapSource;
        }
    }
@return zoom used for the map of a single cache
main/src/main/java/cgeo/geocaching/settings/Settings.java