All language subtitles for 4. Explain how to use null safety with examples

Hello, guys, as this material, I will talk about the north safety and how to deal with that, it

is very easy and very similar to the previous STK and almost nothing different, only about the possible

initialization and also those old buttons that has been duplicated, which shows these buttons.

And I want to show you the old which all team and you watch it and the new teams.

I will give you this link and the description of this tutorial.

OK, and later on this course, I also used the text buttons instead of the flat button, for example,

I used both at.

If an as deprecated, it will still work for you, even if you are on the not safety.

OK, so let's continue answering and here I will show you how to deal with that.

So, as I said, the main difference is about the variable initialization and protect team that thought

to help us to deal with the problems.

So in order to get started, I created a new project and I initialized the scaffold and a container

and a text, this text take Hello World as a strength and I give it some static text outline to the

center and text the style of font size 25, add color of white color.

And I just text.

By the censor, if I say right now, as you can see, it moved up a little bit.

I would keep the center for a good look and I dropped this container was a sensor to be a light as the

center of the screen.

And here I initialize and your file, which is the home which is contained those widgets and.

I use it anyway on screen in here.

For sure, the title deal with signal safety, for example, for sure, it's not a title, but.

Just for clarifying, so let's continue now instead of the strike, let's initialise drink in here and

use it.

So drink, let's say text content equal to hello.

What it's still my Canaro.

We just need to access symbolical.

Let's use this in here.

Let's start the up and see.

So nothing changed.

All right, great.

So what if we says.

And as you can see, it makes our focus on this one here, they ask us if we want to articulate, modify,

let's add it.

Let's start our up and see.

OK, great.

So what's the State Department, the state?

What if I mean thought this strange must be initialized later on so we can initialize it somewhere else

in here?

But for sure, the best place to be initialised is something called and it's state.

Now, I'm explaining this before we start coding.

And if you are new to the flutter, you may not understand it very well, but believe me, later on

it will be very useful and it would be more clear.

So presences in here converted to stateful widget and now there is something called interstate that's

only available in a state for which it OK, it must be straightforward, Richard, in order to use it.

So and here, let's say text contents equal to hello.

What?

Like this Head Start and see what will happen.

OK, so it works well and everything else we expected, so this means that we must initialize this string

or any other if we initialized any end, for example, or any other element we must initialize later

on if we want to use it.

OK, we cannot use it without initializing it.

OK, so I want to show you something else that's delicious and delicious, and if wants is for you to

be all we can add on interrogation Mark in here, but we won't get an error in here.

This error, remind us to add thoughts, as you might might be not OK.

So I focus on this one.

They would ask us to out and I'll check that's ordered and restart the up and see what will happen.

I took my camera because we gave just TextField and not in here.

Let's try it right now.

We can't right now because this text must have a string.

We can't give it to an empty string, for example.

It would work fine, but we we must give it something.

A string.

OK, so.

If it is like this, we can't deal with it by initializing it also in here, so we say in here word,

OK, and we can use it in here, OK?

And for we must ask.

And I'll check it out and see.

So it works as we expect it very well.

Now, if I don't want to initialize that, we can do a check in here, for example, check if it is

not because it is in our volume so we can check it.

I mean, this volume might be not so we can check it if it is equal to not as this is the case, we

show something else, for example.

The value is not let's do like this.

It starts at.

OK, so this is just us up here on the screen.

Let's change this to one eighty one eighty eight, so.

OK, so here it is, the value is not so because the text content is not in here before you become I

mean this for you become printed on the screen.

OK, so once you understand this, you will know how to deal with it very affordable and how to initialize

it and how to use it.

So that's the main thing that you need to know about the safety and as a previous section of the safety,

I showed you money.

I mean, I touched many.

OK, so as I section one and the deal was not safety and now the number of it is three, but it may

change later if I had any new lecture.

And if you press on these resources, you will find any money attached resources.

So check it out.

And if you have any questions later on, you can ask me and I will answer you and details.