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‫-: Hi. Within this lecture we are going to connect our views

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‫with our Java code.

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‫So in order to do that

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‫I'm going to go over to my main activity.

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‫Okay? We are done with the user interface right now

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‫and we are gonna write some code.

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‫So first of all, it's very good idea to start

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‫with writing the methods that we have defined

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‫as on click methods in our xml

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‫so that we don't forget them, okay?

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‫I'm not writing it under on create

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‫but rather under my main activity I'm outside of on create

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‫I'm gonna say public void and I'm going to start with sum.

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‫So this is how we create methods, remember

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‫but we have to add, view view parameter over here

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‫in order to specify this method is going to be called

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‫by a view.

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‫So if you get a error like this

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‫just click over here and hit, hit alt enter

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‫in your keyboard and as you can see it's imported over here

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‫like import view and then say view.

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‫So we are doing this in order to let us know

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‫that this method will be get called by a view

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‫like a button or image view.

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‫So I'm going to continue doing that.

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‫I believe we have deduct, view view, okay, and we are done.

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‫Let's go for multiply.

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‫So public void multiply, view, view.

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‫And then for the last one we are gonna go

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‫for divide public void divide.

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‫And here you go.

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‫Now we are done with all the public methods over here

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‫in order to be sure

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‫that we have the on click methods in our coding section.

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‫So what do we want to do in this app?

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‫We want to get the input of the user right?

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‫We want to get the numbers that our user chooses to give us

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‫and that we are gonna do some kind

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‫of mathematical operation on those numbers

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‫and we are going to display the result on a result text.

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‫So we need our text we use in edit text

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‫inside of our coding section.

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‫We need to connect them first, right?

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‫And maybe you remember how to do this thing.

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‫So I'm gonna do this under on create

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‫and we're gonna talk about why we are doing this

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‫under on create.

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‫So I'm going to start with edit text and here you go.

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‫We have to do alt enter.

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‫So edit text is the type that I'm defining over here

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‫and you can call it whatever you want.

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‫For example, I'm gonna call this number 1 text.

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‫You can call it edit text, you can call it your name.

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‫But after that you have to say find view by Id

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‫and R.id. whatever Id you have given to your edit text.

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‫Like in my case, it's already number 1 text.

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‫So over here I'm choosing the ID that I have given in xml.

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‫Now I'm gonna do the same thing for number 2 text as well.

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‫I'm going to say find view by Id, R.ID dot number 2 text.

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‫And finally we have our text view, right?

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‫So I'm gonna call this result text and say

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‫findview by Id R.id result text.

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‫So beware that these are the same with this

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‫but this is just a coincidence.

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‫You can call this whatever you want, okay?

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‫But this is a convention.

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‫It is fine.

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‫It is a good way to call this things with the

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‫exact functionality that they're

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‫they're going to do in the app.

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‫So you can call this your name as well.

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‫It won't, it won't break, it will work

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‫but it's a good habit to choose good naming.

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‫Okay? So as you can see,

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‫I have all this texts over here like

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‫edit text, edit text two and text view.

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‫Now if I want to get text out of an edit text, I can do it

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‫like this, like number1text.getText, okay?

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‫And then if I say .toString like this

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‫it will give us the string that user has typed

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‫in that edit text.

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‫We are going to discuss why are we adding some two string

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‫or what is the get text and stuff later on.

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‫However, I want you to understand

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‫that we can use this get text .two string methods

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‫in order to get the current string in this edit text.

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‫But there is no point doing that under on create, right?

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‫Because when we create this activity

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‫the edit text will be completely empty like this.

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‫So when a user taps one of these buttons

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‫that's when we try and get the content

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‫of this edit text so that it can actually take these numbers

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‫and add them together and show the result, right?

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‫So we want to do this thing like

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‫number1Text.getText.toString in one of the methods

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‫actually in all of the methods.

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‫So if I write number1Text, can I reach the text,

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‫the variable that I have defined under on create?

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‫Of course I cannot because they are in

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‫different scope right? We have talked about this.

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‫So we have this coding block over here

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‫and this coding block over here, we cannot

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‫actually reach the variable that we have defined over here.

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‫So maybe you can think something like that.

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‫Yeah, let's just copy and paste things over here

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‫and over here and over every method that we have

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‫and it will actually work,

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‫but it's not very efficient, right?

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‫It's not efficient for us because we have to

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‫copy and paste and it's not efficient

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‫for memory consumption as well.

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‫Every time a user taps on one of these buttons

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‫then I will have to create this views from scratch.

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‫So it's kind of inefficient.

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‫So what, what do we do?

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‫Remember we talked about is we can actually

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‫define the variables and also the views inside of our class

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‫but outside all, all the methods so that we can

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‫reach them from anywhere we want,

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‫inside of the class obviously.

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‫For example, we have done this like, int myNumber

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‫so we can reach my number from any method.

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‫We can do the same thing for the edit text

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‫or text view or image view or buttons as well.

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‫For example, I'm gonna copy this

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‫and paste it over here and put a semicolon the end.

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‫Okay, so I'm going to do the same thing over here as well.

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‫Number 2 text

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‫and I'm going to do the same thing over here as well.

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‫So this is defining, okay?

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‫If I delete the types from here like this,

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‫this is initializing.

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‫So right now I'm initializing the views over here

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‫assigning the values to them

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‫and over here I'm defining them.

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‫So right now if I write number 1 text or number 2 text

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‫or result text from anywhere in coding section

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‫then I can actually reach those.

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‫So under on create or under some or under deduct.

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‫And they will be initialized

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‫they will be actually connected

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‫to the related IDs under on create.

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‫So it won't be any problem for me either.

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‫So right now if I come over here and say number 1

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‫as you can see, I can reach it.

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‫So that's good.

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‫Now we have defined all the views

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‫that we are going to be needing

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‫we are going to be using in this app.

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‫Now we can actually move on to the coding section as well.