private boolean updateBackup(boolean pic) {
        StringBuilder sb = new StringBuilder();
        LinkedList<String> help = null;
        if (pic) {
            help = new LinkedList<>(pictureList);
        } else {
            help = new LinkedList<>(currentData);
        }
        if (!pic) {
            sb.append(Integer.toString(latestUrlNo));
            sb.append("\n");
        } else {
            int i = 0;
            int j = 0;
            do {
                if (downloadPicture(help.get(i), j) != false) {
                    j++;
                }
                i++;
            } while (j < 5 && help.size() > i);
        }

        while (help.size() > 0) {
            sb.append(help.pop());
            sb.append("\n");
        }
        String filepath;
        if (pic) {
            filepath = BACKUP_PICTURE_FILE_PATH;
        } else {
            filepath = BACKUP_FILE_PATH;
        }
        try {
            writeFile(sb.toString(), filepath);
        } catch (Exception e) {
            JOptionPane.showConfirmDialog(null, "Backupdatei " + filepath + " kann nicht geupdated werden", "Dateifehler", JOptionPane.OK_CANCEL_OPTION, JOptionPane.ERROR_MESSAGE);
            return false;
        }
        return true;
    }