After creating the repository class, let's create the service class where we will autowire the repository class using the @autowired annotation. Let's create a service class named UserService.kt with the @Service annotation that implements the UserInterface and overrides all functions.

Here is the piece of code for the UserService.kt:

@Service
class UserService: UsersInterface {
    
    @Autowired
    private lateinit var userRepository: UserRepository

    ------
    ------
}

Let's override and modify the functions with the help of UserRepository. Here is the full code of the UserService class:

@Service
class UserService: UsersInterface {
    @Autowired
    private lateinit var userRepository: UserRepository

    override fun getAllUserList(): List<UserModel> {
        return userRepository.getAllUserList()
    }

    override fun getUserByID(id: Int): UserModel? {
        return userRepository.getUserByID(id)
    }

    override fun addNewUser(userModel: UserModel) {
        userRepository.addNewUser(userModel)
    }

    override fun updateUser(userModel: UserModel, id: Int) {
        userRepository.updateUser(userModel, id)
    }

    override fun deleteUser(id: Int) {
        userRepository.deleteUser(id)
    }
}

• getAllUserList(): This function will fetch all the users
• getUserByID(id: Int): This function will fetch a user by ID
• addNewUser(userModel: UserModel): This function will insert a new user
• updateUser(userModel: UserModel, id: Int): This function will update a user by ID
• deleteUser(id: Int): This function will delete a user by ID