Hope this will help
try {
File exportDir = new File(myDir + "/text/", filename);
if (exportDir .getParentFile().mkdirs()) {
exportDir .createNewFile();
FileOutputStream fos = new FileOutputStream(exportDir );
fos.write(outputString.getBytes());
fos.flush();
fos.close();
}
} catch (Exception e) {
e.printStackTrace();
}