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Welcome back in this video, we are going to get started with coddling cold, and the focus of this

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video will be to, first of all, set up Android Studio so that we can use it in order to learn the

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basics very easily.

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And then we're going to learn the difference between Vol and VR.

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These are super important keywords in Scotland development, and they are really the absolute basis

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because you need to have a way to store information for a runtime of your application.

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And in this case, we're storing, for example, the amount that something was clicked.

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So we're storing it in this variable called times clicked.

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But let's go ahead and create a separate project where we are going to not to have all of this boilerplate

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code.

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So the code, it just is created for us in order to get it even something running, let's really have

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a very simplified version of it in Android Studio.

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Therefore, let's go ahead and create a new project, and I'm going to create one with no activity.

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And I'm going to call this one Scotland basics, Caitlin basics like so you can call it however you

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want, and the package name is also not going to be very important in this case because we're not going

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to publish this application.

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It's really just for us to play around with calling.

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The only thing that is important is that you selected Scotland here, which should be done by default.

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And now let's create the project.

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Now what will potentially happen is that this green stays open, and you don't even know that there

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is a second screen open with the Scotland Basic, so you will find that there are two instances of Android

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Studio.

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OK, so let's go ahead and go into the app folder and then into Java.

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And what's important here is that you have Android selected here at the top.

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Otherwise the structure will look differently.

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As you see here.

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If I select Project, for example, of packages, everything looks very different.

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So let's go to Android and then on there Java, let's go under you tutorials, Kotlin basics, or however

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your package name was that you have selected, and let's create a new Kotlin class slash file.

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I'm just going to create a file, not a class and nothing else, just a file that I'm going to call

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basics.

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OK.

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So this creates this basic fact file for me, which is a cotton file.

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The extension KP stands for called then and now.

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Inside of it, you can see that it just has one line of code and that says Package you tutorials dot

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cotton basics.

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If it has any more code in here, you can just delete it.

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What's important is that it is just a Kotlin file.

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OK, now at this point, we can shut down this project part and we can get started with the code.

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So I'm going to start with the main function, so I'm using fun- main and then brackets and then curly

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brackets.

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So this one just ends for function.

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So we are creating a function, and this function is called main, which is a very special function.

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It's not the general function, it's really a function that is the starting point of our application.

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So if I were to create another function here, let's call it.

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Hello.

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You see that it has a different color.

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That's because it doesn't use.

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And second of all, I don't have this play button next to it.

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So this play button is only going to be available for the main function because, as I said, it's the

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entry or starting point for our application.

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It doesn't exist for this Hello keyboard.

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Now, inside of those brackets, I could add parameters, we're going to see what this means later on.

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For now, it doesn't matter.

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And then we have the curly brackets and they are important because they are the body of the function.

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So what's inside of those curly brackets?

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That's the body of the function, and that's where we can add the code that we want to be executed once

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we run the code.

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So if I run this now, nothing will happen because there's no code inside of the curly brackets.

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So even though the Gradle build will run, there's really not anything to be displayed.

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So you can see here no text, no nothing.

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Let's change that by quickly adding a print statement.

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So print is a very special method, and we can now enter something that it should say.

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So I'm just going to say print, hello world.

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So if I run this code again?

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It will display Helloworld here.

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You can see now it says Helloworld, this print method is just a code block that tells our I.D.

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OK, I want to display something so it displays it onto the console, which is this part here at the

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bottom.

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So you see run, you can close this by either clicking on the run here or by clicking this hide button.

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But then you can open it again by clicking on this run option here at the bottom.

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And then you can, of course, make changes to your code.

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So let's change it to, for example, Hello Dennis.

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And run it again.

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And there you are.

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You see it says, hello, Dennis, now in our console, which is this part here at the bottom.

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OK, so that's the print statement, and we're going to use print statements quite often because they

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just allow us to see the value of something.

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In this case, to something will be a variable.

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So I'm just going to go ahead and create a variable and I'm going to give it the name, my name.

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So the variable is going to be called my name.

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And then I'm assigning Dennis to it.

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All right.

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So let's use my name instead of using Dennis here.

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So instead of saying Dennis, I'm just going to say hello, empty space plus and then my name, by the

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way, you can also see that we are using parentheses here.

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So these parentheses that just say that this is a string.

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OK, we're going to learn about the data types in the next couple of videos, but for now, we're just

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focusing on variables.

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So we see that we have this new variable called my name.

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And then inside of it, we stored value.

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So we assign with this equals sign, we store the value Dennis.

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This allows us then to re-use this variable and use it in our print statement.

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So what we're doing here is we're just saying hello and this space and then at the point after that,

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we add the entry of my name.

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OK, so let's run this and see what's going to happen, and you will see that there will be no change.

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It will still say hello, Dennis.

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So now that's changed it to, for example, Frank.

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So my name is going to be frank.

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Now, let's change it.

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And here to bottom it will say Hello, Frank.

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Now there is another thing that we can do with variable, and that is to assign a different value to

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it so I can now go ahead and use my name and assign a new value to it.

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So I could just say, instead of frank, it should say Heidi.

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All right.

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So now my name is not going to be frank, but my name is going to be Heidi at that point, because even

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though it was assigned Frank at the beginning, it was overwritten later on.

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And then when it was actually retrieved or used, it had the value of Heidi.

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So let's run our project again, and we will see that now it says Hello, Heidi.

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So that is pretty much what you can do with variables, you can store values in them and we're going

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to see what kind of values you can store in them because currently we're just storing text in them,

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right?

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In this particular case, even names.

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But of course, you could store other types of text in them as well.

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And now we have used another keyword in the last video, which was vault, so we didn't use VAR, but

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instead we used it.

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Now the difference between VAR and Vault is that a VAR variable can be overwritten.

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A VAR variable can not be overwritten, can only be set once.

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So here we are, setting the value for that variable and it cannot be overwritten, which is why we

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get an error here.

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You see, we get a little problem.

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We can hover over it and it will say a vault cannot be reassigned, so we cannot assign a new value

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to a variable that is using the vault key word when it is created.

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So that means that this line is not going to work.

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Now we can get rid of it and then everything will be fine, but now we have the name of my name.

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So we are writing a variable where we want to only be able to assign it once we don't want our code

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at any point to be able to overwrite that value.

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And that is what you would use to value keyword for.

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And by the way, it's also more efficient in terms of processing power.

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So if you know that you don't want to ever override value for a given variable that you are creating,

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then use the keyword if you're not sure and you believe that you will have to override it at one point.

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Then you use VAR.

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Of course, you can start with volume.

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And then when you realize I actually want to override the value or reassign a new value to this variable,

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then you can change the declaration later on and change that to VAR.

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And you can go ahead and just say, change the name here to Claudia, for example.

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And let's run it real quick, and we'll see if we get.

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Hello, Claudia.

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OK, so that's basically the difference between VAR and Vault.

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In the next video, we're going to look at the data types of numbers.