how to pass function to other class and return response of function to main class in flutter

Question

i have a class that call it in main class but i want pass a function to sub class and run function to sub class and return response of function to main class how to do in flutter dart.

Solution

Do

class subclassName
final function NameOfFunction;

subclassName(this.NameOfFunction);

in main class

subclassName(the function you want to pass);

main

class _MyAppState extends State<MyApp> {
  var _questionIndex = 0;

  void _answerQuestion() {
    setState(() {
      _questionIndex = _questionIndex + 1;
    });
    print(_questionIndex);
  }

  @override
  Widget build(BuildContext context) {
    print("object");
    var questions = [
      {
      'questionText':'What\'s your favorite color?',
      'answers': ['Black','Red','Green','White'],
      },
      {
      'questionText':'What\'s your favorite animal?',
      'answers': ['Rabbit','Snak','Elephant','Lion'],
      },
      {
      'questionText':'who\'s your favorite instructor?',
      'answers': ['suhaib','max','khalid','moh'],
      }

    ];
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('My First App'),
        ),
        body: Column(
          children: [
            Question(
              questions[_questionIndex]['questionText'],
            ),
            ...(questions[_questionIndex]['answers'] as List<String>).map((answer){
              return Answer(_answerQuestion, answer);
            }).toList(),
          ],
        ),
      ),
    );
  }
}

sub class

class Answer extends StatelessWidget {
final String textanswer;
final Function answerQuestion;
  Answer(this.answerQuestion,this.textanswer);

  @override
  Widget build(BuildContext context) {
    return Container(
      child: RaisedButton(
        color: Colors.blue,
        textColor: Colors.white,
              child: Text(textanswer),
              onPressed: answerQuestion,
            ),
    );
  }
}