I have a MVC type architecture for new user registration to my app. The user submits the registration form to the controller servlet. This servlet extracts the user parameters and passes them to a class constructor, which represents (and returns) a template(or dummy) user with all the fields initialized based on the arguments.
I remember people insisting on argument validation in methods or constructors before using them. Now I try to check the arguments for their validity(for example they are not null). So when I find any argument having invalid value, How do I notify the servlet that this particular argument is invalid, because I cannot return a value from the constructor.
Please help me.
Validate before calling the constructor. If anything is wrong get back to user with error. If everything is fine then only call constructor and create objects.