Design of J2EE Dao layer and business logic layer

For example, to create a course selection management system for students, the database has three tables: students, teacher, and course.

Dao layer interface design:
Interface studentdao
{
Public void insertstudent (student Stu );

Public void removestudent (long ID );

Public void updatestudent (student Stu );

Public student findstudent (long ID );

/**
* Other Dao Methods
**/
}

Interface teacherdao
{
Public void insertteacher (teacher tea );

Public void removeteacher (long ID );

Public void updateteacher (teacher tea );

Public Teacher findteacher (long ID );

/**
* Other Dao Methods
**/
}

Interface coursedao
{
Public void insertcourse (course C );

Public void removecourse (long ID );

Public void updatecourse (course C );

Public Teacher findcourse (long ID );

/**
* Other Dao Methods
**/
}

Business layer interface design:
Interface studentservice
{
Public void savestudent (student Stu );

Public void deletestudent (long ID );

Public void updatestudent (student Stu );

Public student getstudent (long ID );

/**
* Other service methods
**/
}

Interface teacherservice
{
Public void saveteacher (teacher tea );

Public void deleteteacher (long ID );

Public void updateteacher (teacher tea );

Public Teacher getteacher (long ID );

/**
* Other service methods
**/
}

Interface courseservice
{
Public void savecourse (course C );

Public void deletecourse (long ID );

Public void updatecourse (course C );

Public Teacher getcourse (long ID );

/**
* Other service methods
**/
}

Write these two interfaces and create their implementation classes respectively, for example:
Public class studentdaoimpl implements studentdao;
Public class studentserviceimpl implements studentservice;

The methods in studentserviceimpl call the interface methods in studentdaoimpl.

The writing of other classes is similar.