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‫Instructor: Hi, within this lecture we are going to learn

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‫about a concept called classes.

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‫So far we have been working with classes anyway, right?

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‫So we have all these methods inside of our main activity.

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‫And if you look closely in your main activity,

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‫main activity is actually a class itself as well.

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‫So we have all these methods and we have all

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‫this class surrounding all these methods as well.

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‫So class is the bigger part, over here,

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‫class is like a blueprint of programming.

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‫So you get to choose your structure,

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‫you get to choose your methods,

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‫you get to choose your variables, properties, like options

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‫that you're gonna get or you are gonna provide in your code.

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‫For example, let us think that we're going to have

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‫some musicians, okay?

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‫We can create some musician names, for example,

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‫like string musician one and string musician two, right?

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‫And assume that we' re going to have the age

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‫of those musicians as well, like age one and age two.

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‫And suppose that you also have instrument of that musicians,

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‫like string instrument one, string instrument two.

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‫So suppose that you're gonna have like a hundred musicians

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‫and it would be a little bit difficult for you

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‫to do it like this.

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‫Like musician one is James, age one is 50,

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‫instrument one is guitar.

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‫So after one point you will lose track

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‫and it will get complicated for you, right?

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‫So rather than doing this, you can create a class or model

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‫of a musician and you can give it any property you want,

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‫and you can have a more structural way of dealing with data.

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‫So this is where class comes in.

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‫Like you can create your own class,

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‫you can create your own structure, your own blueprint,

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‫and you can have your own way

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‫of having properties, having methods.

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‫Over here we have this main activity

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‫and it's a class itself as well.

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‫So this extends to something called a compact activity.

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‫And we're gonna see what extending means later.

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‫Oh, but this is actually a class and we are working inside

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‫of a class anyway, so you should have a class.

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‫And we have created class over here before, right?

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‫We said new Java.

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‫So that's what we're going to do, now.

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‫I'm gonna create a musician's class

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‫and be aware that I'm making this M upper case

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‫because that's how we write class names.

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‫So all we had to do

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‫is just write public class musicians actually,

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‫inside of a Java document.

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‫So this is our class.

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‫Now I get to choose

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‫what kind of properties that I will have

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‫inside of a musician object.

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‫So for example, I can say string name,

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‫and then I can say string instrument.

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‫And if I want to add an age,

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‫I can edit, it's age and that's it.

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‫Now I get to create a musician object

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‫out of a musician class.

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‫It's the same thing like creating a string object

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‫from a string class like this.

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‫So let me come over here

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‫maybe under on create or let me create my own new method,

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‫so that it would be a separate method,

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‫so you can keep track of things in a better way, okay.

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‫You don't have to create methods right now.

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‫All we have to say public void.

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‫And over here, let me call this, make musicians.

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‫So it would be explicit as much as possible, okay?

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‫And under this make musicians method,

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‫I'm going to create a musician object.

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‫So if you come over here and take a look,

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‫we already did something like that.

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‫So it's the, it's basically the same thing

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‫like saying string, my string, okay,

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‫we are gonna say musicians like this.

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‫And as you can see now it's appearing

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‫in the results as well.

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‫So musicians is our class

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‫and we are going to create an object out of that class.

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‫And we can name it anything we want.

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‫Like James for example.

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‫So James is a musician's object right now.

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‫James is not a integer, is not a string, is not a bullion.

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‫James is musicians and I can just say new musicians.

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‫And I can actually give the property values afterwards

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‫if I want to.

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‫Like I can say James dot,

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‫and I can reach all the properties that I have defined

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‫inside of my musicians class.

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‫Now what do I have over there?

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‫I have the name, I have these instrument, I have the age.

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‫Now if I say James dot, I can reach all of those

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‫as you can see, age, instrument, name.

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‫If I had another method or something,

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‫some kind of property over there,

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‫I could have reached those as well.

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‫So I can just say James dot age is 50,

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‫James dot instrument is guitar.

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‫And I can just say James dot name is

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‫of course James itself.

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‫So this is how you deal with classes.

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‫This is how you create models for your own objects.

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‫Now I get to create whatever I want,

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‫like an object inside of my,

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‫under a development environment.

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‫Of course, there are a lot of other things to consider

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‫when you deal with classes

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‫and we're gonna see a lot of those

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‫in the next lecture as well.