private static void splitFile(File f, String fileNamePrefix) throws IOException {
        int qtyRaws;
        int qtyFiles = 8;

        try (FileReader input = new FileReader(f);
             LineNumberReader count = new LineNumberReader(input)) {
            while (count.skip(Long.MAX_VALUE) > 0) {
            }

            qtyRaws = count.getLineNumber() + 1;
        }

        String fileName = f.getName();
        Path dir = Files.createDirectory(Paths.get(f.getParent(), "Parts_of_" + fileName));

        try (BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(f)))) {

            for (int i = 0; i < qtyFiles; i++) {
                String filePartName = String.format("%s_%s.%03d", fileNamePrefix, fileName, i);
                File newFile = new File(dir.toString(), filePartName);
                try (BufferedWriter out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(newFile)))) {
                    for (int j = 0; j < Math.ceil(qtyRaws / qtyFiles); j++) {
                        out.write(reader.readLine());
                        out.newLine();
                    }
                }
            }
        }
    }