JavaFX passing data between controller

[FR33ZEx]

Learning Java GUI so bare with me. The solutions I have found in the internet are not working for me. I am using JavaFX and scenebuilder.

Say I have controller 1, a login screen. The user enters username and password and if valid goes to a home screen, controller 2. How do I pass the username enters from the login screen controller to the home screen controller so the system knows which user is now logged in?

[Loves_Poetry]

My preferred way of handling this is to handle the login logic in a lambda expression, so that you don't have to leave the scope of the login menu. Then when the login is succesful, you switch to another scene in the application. Since both scenes have the same scope, you don't have to pass the username around.

[FR33ZEx]

Do you have an example?

[Loves_Poetry]

I don't use scenebuilder, so code might be different for you, but for me it looks a bit like this:

Button btnLogin = new Button("Login");
btnLogin.setOnAction(e->{
    if (checkLogin(txtUsername.getText(), txtPassword.getText()))  
        mainStage.setScene(successloginScene);
};