Should I separate or keep them in same class? - oop

Question

I have some methods in my UserService.
class UserService {
Token generateTokenForLogin(String phone);
User login(String phone, String token);
Token generateTokenForRegistration(String phone);
User register(String phone, String token);
Token generateTokenForForgotPassword(String phone);
User forgotPassword(String phone, String token, String newPassword);
User updateUser(UpdateUserRequest request);
}
Should I separate these methods to
class LoginService {
Token generateTokenForLogin(String phone);
User login(String phone, String token);
}
class RegistrationService {
Token generateTokenForRegistration(String phone);
User register(String phone, String token);
}
class UserPasswordService {
Token generateTokenForForgotPassword(String phone);
User forgotPassword(String phone, String token, String newPassword);
}
class UserService {
User updateUser(UpdateUserRequest request);
}
Each method have 10+ LOC, I want to know which is a better way, thanks.

Answer 1

In OOP there are the SOLID principles. Where the S stands for Single Responsibility, where each function/class should have a clearly defined purpose. From the looks of it, i'd say your UserService Class does not follow this principle. I would indeed separate out the functionality, but I would have a different approach. Separate it into 2 classes, User Service and Token Generator like....
class UserService {
User login(String phone, String token);
User register(String phone, String token);
User forgotPassword(String phone, String token, String newPassword);
User updateUser(UpdateUserRequest request);
}
class TokenGenerator {
String newLoginToken(String phone);
String newRegistrationToken(String phone);
String newForgotPasswordToken(String phone);
}
Now your classes are seperated appropriately. TokenGenerator is dedicated to generating tokens, and UserService is dedicated to user services.
Seperate note, I like your self-documenting function names, however it seems a little verbose. I changed the function names to be more concise. Lastly, any reason why your "Generate Token" functions return type Token, but the login, register and forgot password token takes type String for token? Use built in variable types to avoid unneeded complexity if you can.
For maximum flexibility and robustness I would suggest creating an interface iUserService. Check the GoogleAPI UserService Interface for an example
Lastly, i thinkIt's great that you are worried about the quality of your code. In the future, I would check out the Code Review Stack Exchange. This exchange is dedicated to these types of questions.