Java recursively gets a small example of all the file paths in a directory

private List<String> ergodic(File file,List<String> resultFileName){
        File[] files = file.listFiles();
        if(files==null)return resultFileName;//Determine if the directory is empty
        for (File f : files) {
            if(f.isDirectory()){//Determine whether folder
                resultFileName.add(f.getPath());
                ergodic(f,resultFileName);//Call itself to find the subdirectory
            }else
                resultFileName.add(f.getPath());
        }
        return resultFileName;
    }

When called, return ergodic(new File(forderPath), resultList);
The result is a directory containing all file paths under subdirectories, including subdirectories of subdirectories...