ExportDatabaseCSVTask

 first :       implementation files('libs/opencsv-2.4.jar')

public class ExportDatabaseCSVTask extends AsyncTask<String, String, String> {
    private File file;
    private WeakReference<Context> context;
    private ProgressDialog dialog;
    private boolean isSuccess = true;
    private final String[] arrStr1 = {"Name", "column 1", "column 2", "column 3", "column 4", "column 5"};
    private String fileName;

    public ExportDatabaseCSVTask(Context ctx) {
        context = new WeakReference<>(ctx);
        Hawk.init(context.get()).build();
    }

    @Override
    protected void onPreExecute() {
        dialog = new ProgressDialog(context.get());
        this.dialog.setMessage("در حال ساخت فایل...");
        this.dialog.show();
    }

    protected String doInBackground(final String... args) {
        makeDir();
        writeData();
        return "";
    }

    private void makeDir() {
        File exportDir = new File(Constants.FOLDER_ADDRESS);
        if (!exportDir.exists()) {
            //noinspection ResultOfMethodCallIgnored
            exportDir.mkdirs();
        }

        ///// set name and type for export file
        fileName = "fileName" + Util.getDate() + ".csv";
        file = new File(exportDir, fileName);
    }

    private void writeData() {

        try {
            boolean isCreated = file.createNewFile();
            if (isCreated) {
                CSVWriter csvWrite = new CSVWriter(new FileWriter(file));
                List<User> users = AppDatabse.getInstance(context.get()).mUserDao().getAll();
                int x = AppDatabse.getInstance(context.get()).mUserDao().countUsers();
                csvWrite.writeNext(arrStr1);
                
                // fill columns
                for (int y = 0; y < x; y++) {
                    String[] arrStr = {users.get(y).getUserName(), String.valueOf(users.get(y).getUserMarhale()),
                            String.valueOf(users.get(y).getTrack1()), String.valueOf(users.get(y).getTrack2()),
                            String.valueOf(users.get(y).getTrack3()), String.valueOf(users.get(y).getTrack4()  };
                    csvWrite.writeNext(arrStr);
                }
                csvWrite.close();
            }

        } catch (IOException e) {
            Log.e("Activity", e.getMessage(), e);
        }
    }

    @SuppressLint("NewApi")
    @Override
    protected void onPostExecute(final String success) {

        if (this.dialog.isShowing()) {
            this.dialog.dismiss();
        }
        if (success.isEmpty()) {
            showSuccessfulDialog();
        } else {
            showFailedDialog();

        }
    }

    private void showSuccessfulDialog() {
        String msg = "اشتراک فایل :";
        setDialog(msg);
        isSuccess = true;
    }

    private void showFailedDialog() {
        String msg = "خطایی رخ داده است.";
        setDialog(msg);
        isSuccess = false;
    }

    private void setDialog(String message) {

        if (!isSuccess) {
            new MaterialAlertDialogBuilder(context.get())
                    .setMessage(message).show();
        } else {
            new MaterialAlertDialogBuilder(context.get())
                    .setMessage(message)
                    .setPositiveButton("بله", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            shareFile2();
                        }
                    })
                    .setNegativeButton("خیر", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            dialog.dismiss();
                        }
                    })
                    .show();
        }
    }

    private void shareFile2() {
        Intent sendIntent = new Intent(Intent.ACTION_SEND);
        sendIntent.setType("application/csv");
        sendIntent.putExtra(Intent.EXTRA_EMAIL, "");
        sendIntent.putExtra(Intent.EXTRA_SUBJECT, "فایل خروجی اپلیکیشن فلان  ");
        sendIntent.putExtra(Intent.EXTRA_TEXT, "");
        String temp_path = Constants.FOLDER_ADDRESS + "/" + fileName;
        File F = new File(temp_path);
        Uri U = Uri.fromFile(F);
        sendIntent.putExtra(Intent.EXTRA_STREAM, U);
        context.get().startActivity(Intent.createChooser(sendIntent, "ارسال به :"));
    }
}

////////////////////////////////////////////////////////////////////////////////

and in your Activty/Fragment  cal this method :

 private void exportCSVTask(Context context) {
        ExportDatabaseCSVTask task = new ExportDatabaseCSVTask(context);
        task.execute();
    }