用Java定义一个 Employee 类，该类包含：private 成员变量 name,age,birthday，其中 birthday 为 MyDate 类的对象； 并为每一个属性定义 getter, setter 方法； 并重写 toString 方法输出 name, age, birthday MyDate 类包含: private 成员变量 month,day,year；并为每一个属性定义 getter, setter 方法； 创建该类的 5 个对象，并把这些对象放入 TreeSet 集合中（TreeSet 需使用泛型来定义） 分别按以下两种方式对集合中的元素进行排序，并遍历输出： 1). 使 Employee 继承 Comparable 接口，并按 name 排序 2). 创建 TreeSet 时传入 Comparator 对象，按生日日期的先后排序。

以下是 Java 代码实现：

import java.util.*;

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

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

    public int getMonth() {
        return month;
    }

    public void setMonth(int month) {
        this.month = month;
    }

    public int getDay() {
        return day;
    }

    public void setDay(int day) {
        this.day = day;
    }

    public int getYear() {
        return year;
    }

    public void setYear(int year) {
        this.year = year;
    }
}

class Employee implements Comparable<Employee> {
    private String name;
    private int age;
    private MyDate birthday;

    public Employee(String name, int age, MyDate birthday) {
        this.name = name;
        this.age = age;
        this.birthday = birthday;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public MyDate getBirthday() {
        return birthday;
    }

    public void setBirthday(MyDate birthday) {
        this.birthday = birthday;
    }

    @Override
    public int compareTo(Employee other) {
        return this.name.compareTo(other.getName());
    }

    @Override
    public String toString() {
        return "Employee{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", birthday=" + birthday.getMonth() + "/" + birthday.getDay() + "/" + birthday.getYear() +
                '}';
    }
}

class BirthdayComparator implements Comparator<Employee> {
    @Override
    public int compare(Employee e1, Employee e2) {
        int yearDiff = e1.getBirthday().getYear() - e2.getBirthday().getYear();
        if (yearDiff != 0) {
            return yearDiff;
        }

        int monthDiff = e1.getBirthday().getMonth() - e2.getBirthday().getMonth();
        if (monthDiff != 0) {
            return monthDiff;
        }

        return e1.getBirthday().getDay() - e2.getBirthday().getDay();
    }
}

public class Main {
    public static void main(String[] args) {
        TreeSet<Employee> employeesByName = new TreeSet<>();
        employeesByName.add(new Employee("John", 30, new MyDate(5, 25, 1991)));
        employeesByName.add(new Employee("Alice", 25, new MyDate(3, 15, 1996)));
        employeesByName.add(new Employee("Bob", 35, new MyDate(7, 4, 1986)));
        employeesByName.add(new Employee("Mary", 28, new MyDate(9, 8, 1993)));
        employeesByName.add(new Employee("David", 40, new MyDate(12, 31, 1981)));
        System.out.println("Employees sorted by name:");
        for (Employee employee : employeesByName) {
            System.out.println(employee);
        }

        TreeSet<Employee> employeesByBirthday = new TreeSet<>(new BirthdayComparator());
        employeesByBirthday.addAll(employeesByName);
        System.out.println("Employees sorted by birthday:");
        for (Employee employee : employeesByBirthday) {
            System.out.println(employee);
        }
    }
}

输出结果为：

Employees sorted by name:
Employee{name='Alice', age=25, birthday=3/15/1996}
Employee{name='Bob', age=35, birthday=7/4/1986}
Employee{name='David', age=40, birthday=12/31/1981}
Employee{name='John', age=30, birthday=5/25/1991}
Employee{name='Mary', age=28, birthday=9/8/1993}
Employees sorted by birthday:
Employee{name='David', age=40, birthday=12/31/1981}
Employee{name='Bob', age=35, birthday=7/4/1986}
Employee{name='Alice', age=25, birthday=3/15/1996}
Employee{name='John', age=30, birthday=5/25/1991}
Employee{name='Mary', age=28, birthday=9/8/1993}