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Welcome back.

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And this video, we are going to look into classes, so let's go ahead and create our own class, and

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therefore we can have a quick look at classes that we have seen already.

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And we've seen this class called main activity, which has this colon app complete activity here, which

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just means that this is going to be the class that our classes inheriting from.

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So this is a concept called inheritance, which we will look at later on.

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But basically, what we see is that we have this class key word and then we have a class name, which

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starts with a capital letter.

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So let's go ahead and create our own class, and I'm going to call this class person.

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So this by itself is valid code already.

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So we have this class person.

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And of course, this class doesn't have any properties.

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It doesn't have any methods, none of that.

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But this is a world class.

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Now, of course, we can extend that.

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We can go ahead and say that it should have a constructor.

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So a constructor allows us to add values to our objects when we create an object of our class, and

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these values could be something like the name.

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And it's just not worth the first name here and last name.

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So we could just go ahead and have these two variables here as the very built of the constructor.

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So these are the parameters of the constructor, so to say.

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And then in curly brackets, that's where the class body starts or where it is.

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So here it starts, and that's where it ends.

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So in here we have our class body and we can do all of the defining of our blueprint.

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So here we can go ahead and create all of the different properties and methods and those kind of things.

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So now this constructive year, as you've seen here, it wasn't even there.

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So there's no constructor there.

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And that is because it is not mandatory if we don't want to define the constructor specifically.

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So if we don't want to go ahead and make this one private, for example, or if we don't want to make

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this public or whatever, so we can just get rid of the constructor and make this code even easier to

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read.

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So we have class person and then and then we have these two values that need to be passed once we create

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an object of our class person.

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So how do we create an object of a class or how do we create an instance of a class?

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That's another way of saying it.

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Therefore, we just go ahead and use the name of our class.

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So in our case person and then in brackets, that's where we want to go ahead and.

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Adds the two values here, so I can see first name and last name, so I could do something like Dennis

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one you.

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All right, that's me.

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So I have this object of class person, which contains those two values, which are first name and last

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name.

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So if I now go ahead and create a variable called Dennis, it's going to be a variable of a type called

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person.

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So I could, of course, state that specifically here.

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I could say Dennis is going to be of type person, but as you know, Carlin does the job for us because

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it understands, OK, if I create an object here after the equal sign of a specific class, then it

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will be of that class.

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So of that type, so to speak.

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So by creating a class, we created our own type.

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All right.

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Such as we have seen in the past already.

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So we used a bunch of different types and now we are using our own type.

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So instead of using incense and strings and those kind of things, we use our own type, which is called

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person whenever we create a class.

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We can also have an in it there.

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So this is to initialize them, which is called once an object is created.

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So as soon as we run this code, it will automatically run this initialize.

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So we can just go ahead and write something like person created and I will run this code.

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We will see that person created is printed to our console.

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All right, so this is the initialism, and you can use it in order to initialize your object.

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Which pretty much means prepare your object.

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Another way of saying person created would be initialized a new person object.

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So that's another way what we could or another thing that we could state here.

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So what we can also say is what person we created.

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So, for example, that we create a person with a specific first and last name.

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So I'm just going to paste the code in here.

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So we say here initialize the new person with first name.

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Then we use the first name of our person and last name with them.

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We used to last name of our person.

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So you can see it's like us creating variables here when we use them in our constructor up there.

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All right.

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So if you run that now, we should see that the person that we created is Dennis Potuto.

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So let me run it again, initialize the new person object with first name Dennis and last name upon

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you, Tom.

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If you want to define default values for your first and last name, for example, you can do so as well.

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So, for example, I'm going to use John Doe here as default values.

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So John Doe.

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And now if I go ahead and create a new object and I'm just going to call this one, John.

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Then this will automatically be John Doe, this person, even though we didn't specifically say that

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this person should be called John Doe when creating this object.

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OK, so when we're getting the instance of this class person and here this is because we defined those

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default values.

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So if we run this, we can see.

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Initialize the new person object, my first name, John, last name, though.

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Let's say we only have the last name.

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So I'm just going to call this person John Peterson.

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It's going to be a new person.

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And here I just say that I want to define the last name as being Peterson.

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So if we run this now?

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Then we will have three people that were created and two or three instances of our class that were created,

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and the last one will have the last name Peterson and the first name John so that we are initialized

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a new person object with a first name, John and last name Peterson.

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All right.

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So this is just one example of how to create classes.

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There are multiple different ones that you can use, and in the next video, we are going to see how

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properties work and also how methods work so how we can create functions within classes.

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So we'll see you there.