public static AbstractTileProvider getPreviousTileProvider() {
        final String tileProviderId = getString(R.string.pref_previous_tileprovider, null);
        tileProvider = TileProviderFactory.getTileProvider(tileProviderId);
        if (tileProvider == null) {
            tileProvider = TileProviderFactory.getAnyTileProvider();
        }
        return tileProvider;
    }
@return zoom used for the map of a single cache
main/src/main/java/cgeo/geocaching/settings/Settings.java