Fllutter Countdown - restart countdown on action

Question

I am using the countdown_flutter component to count down. When starting it is working normal. however, I would like to restart the counter (call the component again) so that the countdown starts again when I press a button or another action:

my code:

_buildCount() {
    return Expanded(
      child: Container(
        child: Center(
          child: CountdownFormatted(
            duration: Duration(seconds: 15),
            onFinish: () {
              _controller.nextQuestion();
              print('finished!');
            },
            builder: (BuildContext ctx, String remaining) {
              return Text(
                remaining,
                style: TextStyle(fontSize: 20),
              ); // 01:00:00
            },
          ),
        ),

      ),
    );
  }

onNext: () {
                setState(() {
                  _scoreKeeper.add(
                    Icon(
                      correct ? Icons.check : Icons.close,
                      color: correct ? Colors.green : Colors.red,
                    ),
                  );

                  if (_scoreKeeper.length < _controller.number) {
                    _buildCount(); // I would like to recall him here
                    _controller.nextQuestion();
                  } else {
                    _stopWatch.stop();
                    FinishDialog.show(
                      context,

                      usuarioLogado: usuarioLogado,

                    );
                  }
                });
              },

Answer 1

I use in my quiz game also a countdown and i realize it like the following code example.

For the first time you can set the countdown value in the initState method and then you can write a resetTimer() function to reset the countdown. This function can you call in onPressed by a RaisedButton or whatever you want. Don't forget to cancel the timer with the cancel() function.

import 'package:flutter/material.dart';
import 'dart:async';

void main() => runApp(TimerExample());

class TimerExample extends StatefulWidget {
  @override
  _TimerExampleState createState() => _TimerExampleState();
}

class _TimerExampleState extends State<TimerExample> {
  Timer _timer;
  int _countdown;

  @override
  void initState() {
    super.initState();
    _countdown = 10;
    startTimer();
  }

  @override
  void dispose() {
    _timer.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Container(
          child: Center(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                Text(_countdown.toString()),
                RaisedButton(
                  onPressed: () => resetTimer(),
                  child: Text('Reset Timer'),
                )
              ],
            ),
          ),
        ),
      )
    );
  }

  void startTimer() {
    const oneSecond = const Duration(seconds: 1);
    _timer = new Timer.periodic(
      oneSecond,
          (Timer timer) => setState(
            () {
          if (_countdown < 1) {
            timer.cancel();
          } else {
            _countdown--;
          }
        },
      ),
    );
  }

  void resetTimer() {
    _timer.cancel();
    _countdown = 10;
    startTimer();
  }
}