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There is no reason to use a function ... as your examples. Stack Exchange Broke The Law – Stack Exchange Broke The Law · 2021-08-12 09:33:02 +00:00 Commented Aug 12, 2021 at 9:33 · And in the reality, in java, these maldas assigned to functional interfaces are implemented as objects via anonymous classes... More on stackoverflow.com

Java does not have functions, only methods. Functions are stand alone and exist outside the context of classes. Since this is not possible in Java, it doesn't have functions. Methods exist only in the context of classes. Even methods that one might consider functions abs, sin, etc. only exist in the context of the Math class and therefore are not functions. In Python, you can have both. If you just define a function outside any class, it is a function, yet if you define a function inside a class, it becomes a method. More on reddit.com

In Java, you can have your main function inside a class, but in order to make it worthwhile, you have to still instantiate an object of that class. That can get kind of confusing, so I prefer to just have an App class with main(), and ALL it does is instantiate a single object. That's it, that object then handles everything else. For example, if I'm making a game, I might do this: public class App { public static void main(String[] args) { Game myGame = new Game(); Game.start(); } } The reason I like this is because it allows some separation of the main entry point from the actual logic of the program. To answer the other part of your question, the difference between a method and a class is this: A class is a structure - a collection of 'like' things. These things, together, make up an object. For example, a Car class might have wheels, doors, windows and so on. A method is an OPERATION on the class - i.e. something that can access information, change information, or requests the information in some way, shape or form. An example of a method on the Car class could be boolean openTrunk(). This method would check the state of the trunk, and if it's closed, open it and return true, else return false. So to 'prevent users from messing up my program', no, that doesn't have anything to do with it, whenever you make any kind of interactive input, such as a textbox, it is up to you to ensure the user doesn't do anything wrong. The best way to think about it: All users are idiots, and will try to enter their birthday where it says Address. You need to be prepared for that, and ensure it doesn't crash your program. Perhaps you might have a Validator class, with a method validateAddress(String input)? This is an example of how you could use both a Class and Method to prevent your user from messing things up. Hope I helped. More on reddit.com