private String appendPath(String path1, String path2) {
        if (path1 == null || path1.length() == 0) {
            return path2 == null ? "." : path2;
        } else if (path2 == null || path2.length() == 0) {
            return path1;
        } else {
            return path1  + File.pathSeparator + path2;
        }
    }