How to change values in OnTap Function when used in a for loop in Flutter

user_12232976 0
Viewed 1399

This is how my code looks like:

        List<Widgets> abc = [];

        for(int a = 0;a<5;a++)
        {
        abc.add(FlatButton(onTap:(){ print(a);},
                           child:Text("Hello - ${a}")
                           )
                 );
        }

When user clicks on "Hello - 2" Button, I want the output on console to be 2 but the output displayed is 5.

I have simplified the original problem in the form of this small programming question.I have checked a lot on internet but was unable to get any answer. Help me out please!!

flutter-layout dart flutter android ios
2 Answers

Your code is working just fine.

List<Widget> abc = [];

  @override
  Widget build(BuildContext context) {
    for (int a = 0; a < 5; a++) {
      abc.add(FlatButton(
          onPressed: () {
            print(a);
          },
          child: Text("Hello - $a")));
    }
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: ListView.builder(
          itemCount: abc.length,
          itemBuilder: (context, index) {
            return abc[index];
          },
        ),
      ),
    );

And how can it return 5 when the max value of a is 4?

user_50495590

You need to store the number in each button. Something like this. I have no idea how to use flutter so however you're supposed to do this, do it that way.

class customButton extends StatelessWidget {
int number = 0;
@override
customButton(int num){
  this.number = num;
}
@override
Widget build(BuildContext context){
return Text('button content' + number.toString());
}
}

class _MyHomePageState extends State<MyHomePage> {

@override
Widget build(BuildContext context) {
List<customButton> buttons = new List();

for(int a = 0; a < 5; a++){
  buttons.add(new customButton(a));
}

return Scaffold(
  appBar: AppBar(
    title: Text(widget.title),
  ),
  body: Center(
    child: Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: buttons
    ),
  )
);
}
}
user_45354590
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