Flutter Function to reload variable-CodePudding

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

CodePudding user response：

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);
    });
  }
},