Answer 1

really java was designed for modular programming just so you know. The only way to "not use modules" in java is to write everything inside of the
public static void main(String[] args){}
block but even that is encapsulated inside of the class it runs in. if you are having trouble understanding java as an object oriented language let me know and ill make you some easy examples with details you can check out. what language were you learning before?