Java中如何实现一个简单的学生请假审批系统？

public class LeaveApprovalSystem {
    // 定义学生列表，保存已注册的学生信息
    List<Student> studentList;
    // 定义教师列表，保存已注册的教师信息
    List<Teacher> teacherList;
    // 定义请假申请列表，保存已提交的请假申请
    List<LeaveApplication> leaveApplicationList;
    
    // 学生注册功能
    public void registerStudent(Student student) {
        studentList.add(student);
    }
    
    // 教师注册功能
    public void registerTeacher(Teacher teacher) {
        teacherList.add(teacher);
    }
    
    // 学生提交请假申请功能
    public void submitLeaveApplication(Student student, LeaveApplication leaveApplication) {
        leaveApplicationList.add(leaveApplication);
    }
    
    // 教师审批请假申请功能
    public void approveLeaveApplication(Teacher teacher, LeaveApplication leaveApplication) {
        leaveApplication.setApprovalStatus("Approved");
    }
    
    // 教师拒绝请假申请功能
    public void rejectLeaveApplication(Teacher teacher, LeaveApplication leaveApplication) {
        leaveApplication.setApprovalStatus("Rejected");
    }
    
    // 学生取消请假申请功能
    public void cancelLeaveApplication(Student student, LeaveApplication leaveApplication) {
        leaveApplicationList.remove(leaveApplication);
    }
    
    // 学生查看请假申请状态功能
    public String getLeaveApplicationStatus(Student student, LeaveApplication leaveApplication) {
        return leaveApplication.getApprovalStatus();
    }
}

public class Main {
    public static void main(String[] args) {
        LeaveApprovalSystem system = new LeaveApprovalSystem();
        Student student = new Student("001", "张三");
        Teacher teacher = new Teacher("1001", "李老师");
        LeaveApplication leaveApplication = new LeaveApplication("2021-01-01", "2021-01-05", "家里有事情");
        
        system.registerStudent(student);
        system.registerTeacher(teacher);
        system.submitLeaveApplication(student, leaveApplication);
        
        system.approveLeaveApplication(teacher, leaveApplication);
        
        String status = system.getLeaveApplicationStatus(student, leaveApplication);
        System.out.println("请假申请状态：" + status);
    }
}