All language subtitles for 4. How to Play Multiple Sounds

So now that we've got our app, which currently has a single button, to be able to play a single sound
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namely note1, how can we have lots of buttons?
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More specifically, seven buttons. So that each of them plays a different sound. As a challenge,
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I want you to build seven buttons on the screen. And they should play the sound from note1 through
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to note7.
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Once you're done, this is what you should have.
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You should have seven buttons, each with a different color so you can tell them apart. And going from
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the top to the bottom,
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when you click on them, you should hear a different sound.
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So seven sounds, seven buttons, each having a different color.
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Don't worry too much about the layout for now.
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We're going to stretch it out a little bit later on.
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But for now, let's just concentrate on the functionality.
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So pause the video, and try to complete this challenge.
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All right.
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So this shouldn't be anything too difficult here.
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But we do have to write quite a bit of code.
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First things first.
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I'm going to get rid of our center widget and we're going to do that by holding down OPTION OR ALT, hitting
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ENTER and remove widgets.
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Now instead, I want my flat button to be inside a column.
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So I'm going to wrap it with a column.
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Now I have a column with a single flat button which simply has the text that says 'Click me' which I don't
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really need anymore.
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So I'm going to delete that.
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But what I do want, is I want our flat button to have a color.
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So I'm going to give it a red color to begin with.
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So this is gonna be our first button.
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And now that I'm done with that flat button, I'm going to copy it and for time sake, I'm gonna paste it
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in here six times. So we should have one, two, three, four, five, six and seven buttons.
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And now we're going to go through this and update each of them.
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So we're going to change the colors, so they each have a different color. And I'm just gonna go down the
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rainbow. If you are more creative, then feel free to pick your color palette
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All right.
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So that's done for all of our buttons.
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And now if we hit save and just check out the result to see if it looks, yes it looks pretty much like
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what we saw in the demo.
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We've got seven buttons, each with a different color.
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Now flat buttons, by default, come with a width and a height. But we don't have to worry about that too
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much for now.
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We're just going to focus on making it play different sounds. Because at the moment, they all play note
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1. And that is of course, we're telling it to play note1.
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Remember that the player is kind of like a C.D. player,
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right?
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And the part that we're putting here is the C.D. We're telling it what to play.
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So we want our first button to play note1.
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The second to play note 2, 3, 4 and so on.
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So now that we've updated all of our file names, telling each button to play a different sound,
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let's hit save and let's see if that worked.
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Perfect.
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So that should have been pretty simple. But you can see that our code isn't very pretty because there's
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a lot of repeated code in here,
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right?
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How can we get rid of the parts that are repeated so that we have less code on our screen which means
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less things to go wrong and less places to look for bugs?
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Well we're going to build a function. Remembering how we built functions in the Dicee module, we started
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with the void keyword,
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and then we gave our function a name. So let's call this one playSound.
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And inside this function, we're going to transplant our two lines of repeated code. And I'm going to simply
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cut it out from our onPressed for our flat button, and I'm going to paste it here to move that
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functionality over. And then, instead of having to type out two lines of code here, I'm simply going to
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call playSound. And let's go ahead and do the same for all the other places. I'm going to copy this function
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playSound and I'm going to replace all the places where I need that functionality namely creating a
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new audio player and playing a sound with this new function that I just created.
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Now some of you already realizing that there's a bit of a problem because we wanted each of the buttons
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to play a different sound, and not for all of them to play the same sound, note1. In Dicee,
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the only type of function that we learned about was the most basic type of function,
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and it looks like this.
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It simply has a name and it allows you to reduce repeated code by bundling code together into a block
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of code, and giving that entire block of code a name to refer to.
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So that means when it's needed, then you can call the function by its name, and it will search out where
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that function was created to execute all the lines of code inside the curly braces of that block of
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code.
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Now we're coming up against a bit of a problem here, because I want this button to play note1 and
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this one to play note2, and 3, and 4, and so on and so forth.
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So we actually need these two lines of code but we need one thing to be different about them.
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We need this to be either 1 or 2 or 3.
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So how can we do this?
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Well this is where input arguments to functions come in handy, because we can simply specify in these
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parentheses or round braces, which we've never used before we've always kept it empty.
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We kept it empty when we called it and
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we kept it empty when we created it. But now is their moment to shine. Inside the parentheses,
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we can specify that this function requires an input, and we specify the data type that the input has
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to be.
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So in this case if we're going from note1 to note7, then that input has to be an integer,
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right?
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It has to be a whole number either 1 or 3 or 7 and whatever it is that we need to replace this particular
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number.
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Now in addition to the data type, we have to give it a name because we can have multiple inputs and we
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need to be able to refer to it inside the function.
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So let's give this one a name of sound
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Number. It's the note number that we want to play.
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Now this is completely arbitrary.
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You can call it anything you want here. But this is what makes sense to me in this moment.
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So right now inside this function, we now have access to that input whatever it may be in the future.
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And we're going to say that instead of hard coding the file name that we're going to tell our player
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to play, we're going to instead replace it with a dollar sign and the name of that input.
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So now depending on what we pass in here, it will be replaced inside here and we'll play the sound that
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we specified in the input.
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So now you can see we've got some red squiggly lines around here because it's saying there's actually
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an input or a argument that's expected, but zero found.
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So let's provide that argument, let's put 1 and 2 and 3 and 4 and 5 and 6 and 7.
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OK.
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So now let's hit save. And we have exactly the same functionality as before. Our sound files are all different
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that's being played.
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But we've reduced the number of lines of code dramatically by using a function to group together the
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functionality that's repeatedly used in our code. In the next lesson,
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for those you guys who are new to programming and you want to learn about how these functions with inputs
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work in more detail,
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that's what I'm going to cover. Now if you're an experienced programmer and you want to skip ahead to
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learn more about Flutter development, then feel free to skip that lesson and continue to the next one.
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So make your choices, and I'll see you on your next lesson.