wyjątek IOExcetion?

Question

Dlaczego mi tutaj wyskakuje IOException przy zapisie i przy odczytywaniu z pliku?

 

package Data;


import java.io.IOException;

public class App {
    public static void main(String[] args){
        FileManager fileManager = new FileManager();
        Staff staff = new Staff();

        staff.add(new Employee("Jan","Kowalski", 2010, 'M',3));
        staff.add(new Employee("Agnieszka","Cuber",2900,'K',3));
        staff.add(new Employee("Adam", "Nowak", 1100, 'M', 4));
        staff.add(new Employee("Sylwia", "Zych", 2100, 'K', 3));
        staff.add(new Employee("Beata", "Dudek", 1900, 'K', 4));

        fileManager.WriteToFile(staff);
        try {
            fileManager.readFromFile();
        }catch (IOException | ClassNotFoundException e){
            e.printStackTrace();
        }

        Employee[] e = staff.getEmployee();
        for(int i = 0;i<staff.getEmployeesNumber();i++){
            System.out.println(e[i]);
        }

    }
}

 

package Data;

import java.io.Serializable;

public class Employee implements Serializable{
    private String firstName;
    private String lastName;
    private int salary;
    private char gender;
    private int section;

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public int getSalary() {
        return salary;
    }

    public int getSection() {
        return section;
    }

    public char getGender() {
        return gender;
    }
    public Employee(){};
    public Employee(String firstName, String lastName, int salary, char gender, int section){
        this.firstName=firstName;
        this.lastName=lastName;
        this.salary=salary;
        this.gender=gender;
        this.section=section;
    }
    public String toString(){
        return firstName + " " + lastName + " Wynagrodzenie: " + salary + " Płeć: " + gender + " Dział: " + section;
    }
}

package Data;
import java.io.*;

public class FileManager  {

    private final String FILE_NAME = "staff.txt";
    public void WriteToFile(Staff p){
        try(
                FileOutputStream ios = new FileOutputStream(FILE_NAME);
                ObjectOutputStream out = new ObjectOutputStream(ios);
                ){
            out.writeObject(p);
        } catch(IOException e){
            System.out.println("Błąd podczas zapisu danych");
        }
    }

    public Employee readFromFile() throws FileNotFoundException, ClassNotFoundException, IOException {
        Employee p1 = null;
        try (
                FileInputStream fis = new FileInputStream(FILE_NAME);
                ObjectInputStream in = new ObjectInputStream(fis);
        ) {
            p1 = (Employee) in.readObject();
        } catch (FileNotFoundException e) {
            System.out.println("Nie znaleziono pliku");
        } catch (IOException e) {
            e.printStackTrace();
            // System.out.println("Błąd podczas wczytywania danych");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return p1;
    }

}

package Data;
public class Staff {
    private static final int MAX_EMPLOYEES = 100;
    private Employee[] employee;
    private int employeesNumber;

    public Employee[] getEmployee() {
        return employee;
    }

    public Staff() {
        employee = new Employee[MAX_EMPLOYEES];
        employeesNumber=0;
    }

    public void add(Employee e) {
        if (employeesNumber<MAX_EMPLOYEES){
            employee[employeesNumber]=e;
            employeesNumber++;
        }


    }
}