CODEWITHSUNDEEP
flutterdart
joe
joe

Reputation: 9494

Instantiate child button with given value, but it is not changed

I am learning new Dart/Flutter and try to make my own exercise. I believe I am missing something fundamental here.

Problem:
My button is showing question mark. But I instantiate it with value already

Question:
How to instantiate button with given text?

import 'package:complete_guide/question.dart';
import 'package:flutter/material.dart';

import 'answer.dart';


void main() {
  runApp(MyApp());
}


class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  int index = 0;
  List<String> questions = [
    "How may I help you?",
    "What is you favorite dog?"
  ];

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

  void showText(inputText){
    print(inputText);
  }

  @override
  Widget build(BuildContext context) {

    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text("Stay Strong")
        ),
         body: Center(
           child: Column(
             children: [
               Question(questions[index]),
               Answer("iddqd", _answerQuestion),
               Answer("idkfa", _answerQuestion),
               Answer("show me the money", _answerQuestion),
             ],
           ),
         ),
      )
    );
  }
}

class Answer extends StatelessWidget {
  final Function selectHandler;
  String answerText = "?";

  Answer(answerText, this.selectHandler);

  @override
  Widget build(BuildContext context) {
    return Container(
      width: double.infinity,
      child: ElevatedButton(
        child: Text(answerText),
        onPressed: selectHandler,
      )
    );
  }
}


class Question extends StatelessWidget {
  final String questionText;

  Question(this.questionText);

  @override
  Widget build(BuildContext context) {
    return Container(
      width: double.infinity,
      margin: EdgeInsets.all(10),
      child: Text(
        this.questionText,
        style: TextStyle(fontSize: 20, color: Colors.orange),
        textAlign: TextAlign.center,
      ),
    );
  }
}

Upvotes: 0

Views: 56

Answers (1)

Christopher Moore
Christopher Moore

Reputation: 17143

Please do not ignore analyzer warnings. They are there for a reason.

First, answerText should be marked as final. It should not be initialized so that it can be assigned a value in the constructor. Finally, you need to use the this. syntax that you've used for all of your other constructor parameters.

There is also no need of providing a default value of '?' for answerText because the constructor uses it as a required parameter, so that default value will never be used.

class Answer extends StatelessWidget {
  final Function selectHandler;
  final String answerText;

  Answer(this.answerText, this.selectHandler);

  @override
  Widget build(BuildContext context) {
    return Container(
      width: double.infinity,
      child: ElevatedButton(
        child: Text(answerText),
        onPressed: selectHandler,
      )
    );
  }
}

Upvotes: 1

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