Your First Flutter App: Polishing the App

In the previous challenge, I mentioned that there’s another way to calculate the difference that requires fewer lines of code - and that’s the subject of this challenge.

The new algorithm looks like this:

First, subtract the target value from the slider’s value. Then, if the result is a negative number, multiply it by -1 to make it a positive number.

At this point, pause the video and try changing the difference calculation to this new algorithm. Then keep watching to compare your work to my solution.

Alright that’s it - good luck.

How’d that challenge go for you? Hopefully, you did okay, but if you got stuck, feel free to follow along with me. With main.dart open, we’ll head over the pointsForCurrentRound method.

Firstly, we’ll delete all the code underneath the variable declarations. Then, we are gonna add a new variable for the difference.

int difference = _model.target - _model.current;

Then, we check if there’s a negative value. If so, we’ll multiply the difference by negative one, turning it positive.

if (difference < 0) {
    difference *= -1;
}

I hope that went well for you. Believe it or not, there’s actually a way to write this with even less code. We’ll take a look at this in the next episode.