Java Lesson 8 | Intro to using multiple classes

Hey, this is Jake with Mac Heads 101. It's going to be another Java tutorial, and today I'm going to be giving you an intro to using multiple classes. I'm going to be making a couple more tutorials on this, but it's just going to be an introduction.

So, the first thing we have to do, um, obviously, is actually create a new class. So, file, new class, and that's source folders, the projects, which was our project. A name, and I'll just call it "second" because I don't really need to call it anything else. All right, so this is our second class.

What I'm going to do is I'm going to build a method in here, right? And then I'm going to be able to call that method in this class, and I'm going to show you how. We're not building a main method in here because Java actually runs from this main method. In this main method, we're going to be calling a method from this class.

So, I'm just going to make a very simple method, public void, and I'm going to explain what all this means. Print, and I'm going to call it print. All right, public means it is a public method, which means I can use it in this class. All the other classes have access to it. If I made it private, I would not be able to call the method in this class.

Void means it does not return a value, as in if I had something like, um, public double, I would have to make it return a double. So, like, return 18, and then I could, when I called that method, I could set a variable equal to that, um, because it was returning 18. But void means it's not going to be returning anything because all we're going to do is printing.

And I got a little ahead of myself there, so I apologize. But, um, system.out.printLn, and in here, I'm just gonna be writing "Hello, World." So I can't make anything better to write.

All right, so we have a method called print. So the first thing we have to do here is create an object for the second class. So, seconds, and I'll call s equals new second, and empty parameters.

Okay, so now we have a method, an object, and in order to call, um, a method, we do that from that class. We do that object dot, and our method name was print, and it took no parameters.

And so if I run it, it calls that print method, and it prints "Hello, World." All right, and so that is just a really quick introduction to, um, using multiple classes.

In the next tutorial, I'm going to be getting a little more in depth. I'm going to be talking about methods that return values, methods that take parameters, possibly setters, getters, and constructors if I have time. So I'll see you the...