如何使用Java编写一个简单的学生请假审批结果通知系统？

import java.util.ArrayList;
import java.util.List;

class Student {
    private String name;
    private List<LeaveApplication> applications;

    public Student(String name) {
        this.name = name;
        this.applications = new ArrayList<>();
    }

    public void submitLeaveApplication(String leaveDate, String reason) {
        LeaveApplication application = new LeaveApplication(this, leaveDate, reason);
        applications.add(application);
    }

    public List<LeaveApplication> getApplications() {
        return applications;
    }

    public String getName() {
        return name;
    }
}

class LeaveApplication {
    private Student student;
    private String leaveDate;
    private String reason;
    private boolean approved;

    public LeaveApplication(Student student, String leaveDate, String reason) {
        this.student = student;
        this.leaveDate = leaveDate;
        this.reason = reason;
        this.approved = false;
    }

    public Student getStudent() {
        return student;
    }

    public void setApproved(boolean approved) {
        this.approved = approved;
    }

    public boolean isApproved() {
        return approved;
    }

    public String getLeaveDate() {
        return leaveDate;
    }

    public String getReason() {
        return reason;
    }
}

class Teacher {
    public void approveLeaveApplication(LeaveApplication application) {
        application.setApproved(true);
    }
}

class Admin {
    public void processLeaveApplications(List<LeaveApplication> applications) {
        for (LeaveApplication application : applications) {
            if (application.isApproved()) {
                // 发送请假审批通过通知给学生
                System.out.println("请假申请已通过：" + application.getStudent().getName());
            } else {
                // 发送请假审批拒绝通知给学生
                System.out.println("请假申请已拒绝：" + application.getStudent().getName());
            }
        }
    }
}

public class LeaveApprovalSystem {
    public static void main(String[] args) {
        Student student = new Student("小明");
        student.submitLeaveApplication("2021-01-01", "家中有事");
        
        Teacher teacher = new Teacher();
        List<LeaveApplication> applications = student.getApplications();
        for (LeaveApplication application : applications) {
            teacher.approveLeaveApplication(application);
        }
        
        Admin admin = new Admin();
        admin.processLeaveApplications(applications);
    }
}