SAVE + READ FILE TXT

- Save file txt

FileOutputStream fos = openFileOutput("khoapham.txt", Context.MODE_PRIVATE);
fos.write(noidung.getBytes());
fos.close()

- Read file txt

FileInputStream fis = openFileInput("khoapham.txt");
BufferedReader br = new BufferedReader(new InputStreamReader(new DataInputStream(fis)));
String line = "";
while( (line = br.readLine()) != null ){
txtvNoiDung.append(line);
txtvNoiDung.append("\n");
}