Xuất dữ liệu ra file bị lỗi (Lần 2)

[dau_nam]

Mình không hiểu bị lỗi gì đấy mn à - nó bị xuất ra dữ liệu gì á

Đây là code ghi file nè

   public class FileManager  {
    public static final String STUDENT_FILE_NAME = ("student.txt");
    /**
     * save list student to file
     * 
     * @param studentList: list student to save
     */
    public void write(List<Staff> studentList)throws FileNotFoundException {
        FileOutputStream fos = null;
        ObjectOutputStream oos = null;
        try {
            FileInputStream fw = new FileInputStream("student.txt");
            FileOutputStream rr = new FileOutputStream("student.txt");
            Writer out = new OutputStreamWriter(rr, "UTF8");
            fos = new FileOutputStream(new File(STUDENT_FILE_NAME));
            ObjectOutputStream ss = new ObjectOutputStream(rr);
            ss = new ObjectOutputStream(fos);
            ss.writeObject(studentList);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            closeStream(fos);
            closeStream(oos);
        }
    }
    /**
     * read list student from file
     * 
     * @return list student
     */
    public List<Staff> read() {
        List<Staff> studentList = new ArrayList<>();
        FileInputStream fis = null;
        ObjectInputStream ois = null;
        try {
            fis = new FileInputStream(new File(STUDENT_FILE_NAME));
            ois = new ObjectInputStream(fis);
            studentList = (List<Staff>) ois.readObject();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } finally {
            closeStream(fis);
            closeStream(ois);
        }
        return studentList;
    }
    /**
     * close input stream
     * 
     * @param is: input stream
     */
    private void closeStream(InputStream is) {
        if (is != null) {
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    /**
     * close output stream
     * 
     * @param os: output stream
     */
    private void closeStream(OutputStream os) {
        if (os != null) {
            try {
                os.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    public Staff ReadFile(){
        Staff c=new Staff();
                try {
                    FileInputStream fis = new FileInputStream("student.txt");
                    ObjectInputStream ois = new ObjectInputStream(fis);
                   Object obj= ois.readObject();
                    c = (Staff) obj; 
                
                    System.out.println(c.toString());
                    ois.close();
                    System.out.println("Press Any Key To Continue...");
                    new java.util.Scanner(System.in).nextLine();
                } catch (Exception ex) {
                    System.out.println(ex);
                }
                return c;
    }
}

Còn đây là code nhân dữ liệu từ ArrayList khi nhập vào nè

public class ManageStaff implements Serializable{
        public static boolean isNumeric(String str) {
                return str.matches("-?\\d+(\\.\\d+)?");
            }
            
            ArrayList<Staff> listStaff= new ArrayList<>();
        ArrayList<Marketing> Mkt = new ArrayList<>();
        ArrayList<Manager> MaNa = new ArrayList<>();
        Staff staff=new Staff();
        Scanner input = new Scanner(System.in);
        ClearDisplay Cls=new ClearDisplay();
        private FileManager fileManager;
        List<Staff> ss;
        // lưu thông tin nhân viên
        
        public ManageStaff(){
                fileManager = new FileManager();
                ss = fileManager.read();
        }
        
        /// NHAP NHAN VIEN ( nhan viên )
       public void InputStaff(){
      
                boolean check= false;
                while(!check){
                    System.out.print(" ");
                    try{
                            
                                Cls.cls();
                                System.out.print("Nhập số lượng nhân viên cần nhập : ");
                                int Amount=input.nextInt();
                                FileWriter fw = new FileWriter("student.txt");
                                for (int i = 0; i < Amount; i++) {
                                Staff staff = new Staff("", "",0);
                                staff.inputStaff();
                                listStaff.add(staff); 
                                fileManager.write(listStaff);
                             
                                } 
                        }
                    catch(Exception e){
                        System.out.println("Giá trị phải là số, hãy nhập lại...");
                        input.nextLine();
                        break;
                        }
                        break;
                    }
                   
        }
}