Get me out of doubt, for example when doing a program with mvc, since the view sends the messages to the controller so that this in turn sends the message to the model, then in the model goes the logic of the application, in the controller is the bridge between the view and the model, and ps the model only receives the actions made by the user and gives the respective answers, my question is as follows: When making a desktop application for example: a login, the person writes their respective user and password, and this travels to the controller which will ask the model if it is correct or not, because where I write the messages that will be returned to the user, incorrect password example, I write it in the model, controller or in the view, I can explain please.
Another query: When doing the validations for example of numbers, I believe in the model a validator class, which I call it in the controller ?, or simply what is valid in the model, which ps for the login example, when I enter the wrong password from the model with a method return a String with the message.
If you were so kind in answering me and if it is with a basic example it would be better, thank you.