مشکل در نمایش درصد پیشرفت هنگام دانلود فایلهایی غیر از عکس و آهنگ

سلام من وقتی از پروژه file downloader استاد استفاده میکنم هنگام دانلود فایل هایی مثل txt یا apk دانلود انجام میشه اما پروگرس بار حرکتی نمیکنه ولی برای فایل های عکس یا آهنگ مشکلی نیست و همه چیز خوب پیش میره

این هم کد:

 public class FileDownloader {

    public static void download(final String downloadPath, final String filepath, final OnProgressDownloadListener listener) {
        Thread thread = new Thread(new Runnable() {

            @Override
            public void run() {
                try {
                    URL url = new URL(downloadPath);
                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.setDoOutput(true);
                    connection.connect();

                    final int fileSize = connection.getContentLength();

                    File file = new File(filepath);
                    if (file.exists()) {
                        file.delete();
                    }

                    FileOutputStream outputStream = new FileOutputStream(filepath);

                    InputStream inputStream = connection.getInputStream();
                    byte[] buffer = new byte[G.DOWNLOAD_BUFFER_SIZE];
                    int len = 0;
                    int downloadedSize = 0;
                    while ((len = inputStream.read(buffer)) > 0) {
                        outputStream.write(buffer, 0, len);
                        downloadedSize += len;

                        final float downloadPercent = 100.0f * (float) downloadedSize / fileSize;
                        if (listener != null) {

                            final int finalDownloadedSize = downloadedSize;
                            G.HANDLER.post(new Runnable() {

                                @Override
                                public void run() {
                                    listener.onProgressDownload((int) downloadPercent, finalDownloadedSize, fileSize);
                                }
                            });
                        }

                    }

                    outputStream.close();
                }
                catch (MalformedURLException e) {
                    e.printStackTrace();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });

        thread.start();
    }
}

OnProgressDownloadListener listener = new OnProgressDownloadListener() {

                                    private String convertByteToMB(int byteLength) {
                                        float sizeInKB = (float) byteLength / 1024;
                                        float sizeInMB = (float) sizeInKB / 1024;
                                        return String.format("%.1fMB", sizeInMB);
                                    }


                                    @Override
                                    public void onProgressDownload(int percent, int downloadedSize, int fileSize) {
                                        prgDownload.setProgress(percent);
                                        txtDownload.setText(percent + "% " + convertByteToMB(downloadedSize) + "/" + convertByteToMB(fileSize));
                                        if (percent >= 100) {
                                            txtDownload.setText("Download Complete");
                                        }
                                    }
                                };
FileDownloader.download(filepath, G.DIR_APP + "/" + filename, listener);