设计Person类，有姓名、地址、电话号码和电子邮件等属性。其子类为Student和Employee，其中Employee类又有教员类Faculty和职员类staff。学生类有班级状态（大一、大二、大三或大四），这些状态为常量。Employee类有办公室、工资和受聘日期。定义一个名为MyDate的类，包含year、month和day数据域。Faculty类有办公时间和级别。Staff类有职务称号。重写每个类中的toString方法，显示相应的类名和人名。 编写测试类Test1，要求随机产生不同的对象，并将这些对象存储到数组中，并用方法printMessages(Person[] persons)将对象的信息输出。 版本2： 在上面实现类的基础上，为每个类增加一个将当前对象序列化到指定文件的方法writeToFile(File f)。为Student类创建一个新的子类Postgraduate，有研究方向和导师姓名两个新增数据域。编写测试类Test2，要求随机产生不同的对象，并将这些对象序列化到指定的文件中，并用方法printMessages(Person[] persons)将对象的信息输出。

好的，我理解了您的问题。以下是第一个问题的回答：

public class Person {
    private String name;
    private String address;
    private String phoneNumber;
    private String email;

    public Person(String name, String address, String phoneNumber, String email) {
        this.name = name;
        this.address = address;
        this.phoneNumber = phoneNumber;
        this.email = email;
    }

    @Override
    public String toString() {
        return "Person: " + name;
    }
}

public class Student extends Person {
    public static final int FRESHMAN = 1;
    public static final int SOPHOMORE = 2;
    public static final int JUNIOR = 3;
    public static final int SENIOR = 4;

    private int status;

    public Student(String name, String address, String phoneNumber, String email, int status) {
        super(name, address, phoneNumber, email);
        this.status = status;
    }

    @Override
    public String toString() {
        return "Student: " + super.toString();
    }
}

public class Employee extends Person {
    private String office;
    private double salary;
    private MyDate hireDate;

    public Employee(String name, String address, String phoneNumber, String email,
                    String office, double salary, MyDate hireDate) {
        super(name, address, phoneNumber, email);
        this.office = office;
        this.salary = salary;
        this.hireDate = hireDate;
    }

    @Override
    public String toString() {
        return "Employee: " + super.toString();
    }
}

public class Faculty extends Employee {
    private String officeHours;
    private String rank;

    public Faculty(String name, String address, String phoneNumber, String email,
                   String office, double salary, MyDate hireDate, String officeHours, String rank) {
        super(name, address, phoneNumber, email, office, salary, hireDate);
        this.officeHours = officeHours;
        this.rank = rank;
    }

    @Override
    public String toString() {
        return "Faculty: " + super.toString();
    }
}

public class Staff extends Employee {
    private String title;

    public Staff(String name, String address, String phoneNumber, String email,
                 String office, double salary, MyDate hireDate, String title) {
        super(name, address, phoneNumber, email, office, salary, hireDate);
        this.title = title;
    }

    @Override
    public String toString() {
        return "Staff: " + super.toString();
    }
}

public class MyDate {
    private int year;
    private int month;
    private int day;

    public MyDate(int year, int month, int day) {
        this.year = year;
        this.month = month;
        this.day = day;
    }
}

public class Test1 {
    public static void main(String[] args) {
        Person[] persons = new Person[10];
        Random random = new Random();

        for (int i = 0; i < 10; i++) {
            int rand = random.nextInt(4);
            String name = "Person " + i;
            String address = "Address " + i;
            String phoneNumber = "Phone " + i;
            String email = "Email " + i;

            if (rand == 0) {
                persons[i] = new Student(name, address, phoneNumber, email, Student.FRESHMAN);
            } else if (rand == 1) {
                persons[i] = new Faculty(name, address, phoneNumber, email, "Office " + i, 50000, new MyDate(2021, 1, 1), "9:00 - 17:00", "Professor");
            } else if (rand == 2) {
                persons[i] = new Staff(name, address, phoneNumber, email, "Office " + i, 40000, new MyDate(2021, 1, 1), "Staff " + i);
            } else {
                persons[i] = new Employee(name, address, phoneNumber, email, "Office " + i, 60000, new MyDate(2021, 1, 1));
            }
        }

        printMessages(persons);
    }

    public static void printMessages(Person[] persons) {
        for (Person person : persons) {
            System.out.println(person);
        }
    }
}

以上是第一个问题的回答，如果您有任何疑问，可以随时问我。