@SuppressWarnings("unused")
	private void checkTileServers() {
        for (TileServer tileServer : TILESERVERS) {
            String urlstring = getTileString(tileServer, 1, 1, 1);
            try {
                URL url = new URL(urlstring);
                Object content = url.getContent();
            } catch (Exception e) {
                log.log(Level.SEVERE, "failed to get content from url " + urlstring);
                tileServer.setBroken(true);
            }
        }
    }