All language subtitles for 011 Required Parameters_en

At the end of the last section, we added in this floating action, but button which it right here,

what if we hover over it?

You'll see that there's a little bit of a warning that says the parameter on press is required.

Let's take a look at the documentation around floating action button and see if we can't get a better

idea of what's going on.

So I'm going to go back over to my letter documentation, and again, on the top right hand side, I'll

look up floating action button.

And then once I pull up the documentation for that class, I'll scroll down to the constructor.

OK, so here's the floating action button constructor inside the list of all these named parameters.

You'll notice that there's one called on press right here and that's exactly what that warning message

was complaining about.

Now, right in front of Unpressed, you'll notice that there's this thing called at required.

At required.

Right here, as you might guess, means that we are required to pass in some value for this unpressed

property.

So if we create a action floating action button, we have to pass in a value for unpressed.

So let's first just add in that name property and then we'll figure out what value we're going to pass

into it.

Back inside my code editor, I'm going to expand the floating action button, I'll add in unpressed.

And then we'll just leave it right there.

We're going to go back over to the documentation very quickly and figure out what we need to assign

to this.

OK, so back over here, that type of unpressed says that it is supposed to be a void callback or I

don't know about you, but that sounds kind of scary.

Let me give it to you in very simple English.

Essentially, we have to pass in a function to this unpressed property.

Any time the user presses on the button, the function that we pass in will be invoked.

So all we have to do over here for unpressed is assign a function or create a function.

So to create a function right here, I'll put my set of parentheses and then my curly braces like so.

So any time a user presses this button, this function right here is going to be executed to test out

that behavior, let's add in a print statement inside of it.

So let's say print high there like so.

And then don't forget, we need to add a comma at the end of the function, otherwise the entire functionally

collapsed automatically.

It's going to put a comma right there.

So let's now save this, we'll try refreshing our emulator again and seeing if we can't get this print

message to display if we tap on that button.

So I'll pull up in my terminal, I'll hit Shift Oregon to reload our application.

Now I see a button on the bottom right hand side, it looks like the button is just a very plain blue

button and it's not currently showing that kind of plus inside of it that we had wanted.

So we're going to do a little bit of work on that front.

But let's see if we can press it and see that print statement appear.

So if I click on the button, sure enough, we see how they're inside of our terminal.

OK, well, that definitely works out.

So let's take a quick pause right here.

We'll come back the next section and we're going to figure out how we can get that little plus icon

to display inside the button as well.

It's a quick break and we'll see you in just a minute.