public void saveRoster() throws RosterAccessException {
    try {
      PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(ROSTER_FILE)));

      for (Student eachStudent : students.values()) {
        out.println(
            eachStudent.getStudentId()
                + DELIMITER
                + eachStudent.getFirstName()
                + DELIMITER
                + eachStudent.getLastName()
                + DELIMITER
                + eachStudent.getCohort());

        out.flush();
      }

      out.close();
    } catch (IOException e) {
      throw new RosterAccessException();
    }
  }