class IfcSpfReader {

    public static List<String> showFiles(String dir) {
        List<String> goodFiles = new ArrayList<>();

        File folder = new File(dir);
        File[] listOfFiles = folder.listFiles();

        for (int i = 0; i < listOfFiles.length; i++) {
            if (listOfFiles[i].isFile())
                goodFiles.add(listOfFiles[i].getAbsolutePath());
            else if (listOfFiles[i].isDirectory())
                goodFiles.addAll(showFiles(listOfFiles[i].getAbsolutePath()));
        }
        return goodFiles;
    }

}