Flutter Function to reload variable

Question

I wanted to make like a currency converter so I created this,

final montant = TextEditingController()..text = '500';
double convertEuro(montant) {
  double convtEur = (double.parse(montant.text) / 3.2);
  return convtEur;
}

double converted = 0;

I had a problem with my function here because the function when the screen loads it's null so I created that converted variable ( It's a stupid move I know at least to get rid of the error on my screen but only showing the initial value from my textController above

Text(
    "${double.parse(montant.text)}" +
        "DT = $converted" +
        " €",
 )

Anyway, the function is triggered when a button is pressed.

onPressed: () {
                if (_formKey.currentState.validate()) {
                  converted = convertEuro(montant);
                }
              },

Can anyone help me how to change that variable value and make it change on my screen when the button is pressed?

Screenshot

@ישואוהבאותך : Thank you . Last question Can I use it on multiple variables on same time .? like updating 3 or 4 variables in same setState? — LearningFlutterDev
– LearningFlutterDev, Commented Nov 26, 2021 at 18:36
Yes, you can set multiple variables. You can also just call the setState without any code inside of it. something like this: setState(() { }); — ישו אוהב אותך
– ישו אוהב אותך, Commented Nov 26, 2021 at 18:40

Shourya Shikhar · Accepted Answer · 2021-11-26 18:22:23Z

0

You can do like this:

setState(() {
  converted = convertEuro(montant);
});

In this, you're basically doing a rebuild of the widget. Thus to implement this in your code, put setState under the onPress:

onPressed: () {
  if (_formKey.currentState.validate()) {
    setState(() {
      converted = convertEuro(montant);
    });
  }
},

answered Nov 26, 2021 at 18:22

Shourya Shikhar

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2 Comments

LearningFlutterDev Over a year ago

Yes great Thank you . Last question Can I use it on multiple variables on same time .? like updating 3 or 4 variables in same setState?

Shourya Shikhar Over a year ago

@LearningFlutterDev yes, you can.

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