Kuis: Catat Skor

Termasuk bagian Proyek dalam perjalanan Flutter di Coddy. Pelajaran 13 dari 36.

Kuis lebih menyenangkan jika kamu bisa melihat perkembanganmu. Simpan skor dalam state, tambahkan satu poin untuk setiap jawaban yang benar, lalu tampilkan di bilah atas.

Tempat terbaik untuk menghitungnya adalah _pick, di dalam setState yang sama dengan tempat menyimpan jawaban. Bandingkan jawaban yang kamu berikan, answer, dengan jawaban yang benar:

setState(() {
  _picked = answer;
  if (answer == _question.correct) {
    _score++;
  }
});

Pengaman di bagian atas _pick sudah mencegah ketukan kedua, jadi setiap pertanyaan hanya bisa menambah paling banyak satu poin.

AppBar menerima actions:, yaitu list widget di sisi kanannya. Letakkan skor di sana, bungkus dengan Center agar posisinya berada di tengah tinggi bilah, dan beri padding 16 piksel di sisi kanan.

Tantangan

Sedang

Simpan skor:

tambahkan int _score = 0; ke state
di _pick, tambahkan satu ke nilainya saat jawaban benar
tampilkan Score: 0 (dengan skor sebenarnya) di actions bilah atas, dengan gaya titleMedium dari tema, di tengah, dengan padding 16 piksel di sebelah kanan

Coba sendiri

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
      ),
      home: const QuizScreen(),
    );
  }
}

class Question {
  const Question(this.text, this.answers, this.correct);

  final String text;
  final List<String> answers;
  final int correct;
}

const List<Question> questions = [
  Question('Which widget stacks its children from top to bottom?', ['Row', 'Column', 'Stack', 'Wrap'], 1),
  Question('Which language do you write Flutter apps in?', ['Kotlin', 'Swift', 'Dart', 'JavaScript'], 2),
  Question('What does setState do?', ['Rebuilds the widget', 'Saves the app', 'Closes the screen', 'Plays a sound'], 0),
  Question('Which widget shows a list you can scroll?', ['Container', 'SizedBox', 'Padding', 'ListView'], 3),
  Question('Which widget adds space around its child?', ['Padding', 'Center', 'Icon', 'Text'], 0),
];

class QuizScreen extends StatefulWidget {
  const QuizScreen({super.key});

  @override
  State<QuizScreen> createState() => _QuizScreenState();
}

class _QuizScreenState extends State<QuizScreen> {
  int _index = 0;
  int? _picked;

  Question get _question => questions[_index];
  bool get _answered => _picked != null;
  bool get _isLast => _index == questions.length - 1;

  void _pick(int answer) {
    if (_answered) return;
    setState(() {
      _picked = answer;
    });
  }

  void _next() {
    setState(() {
      _index++;
      _picked = null;
    });
  }

  Color? _colorFor(int answer) {
    if (!_answered) return null;
    if (answer == _question.correct) return Colors.green;
    if (answer == _picked) return Colors.red;
    return null;
  }

  @override
  Widget build(BuildContext context) {
    final question = _question;
    final textTheme = Theme.of(context).textTheme;
    return Scaffold(
      appBar: AppBar(title: const Text('Flutter Quiz')),
      body: Padding(
        padding: const EdgeInsets.all(24),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            Text(
              'Question ${_index + 1} of ${questions.length}',
              style: textTheme.labelLarge,
            ),
            const SizedBox(height: 24),
            Text(question.text, style: textTheme.headlineSmall),
            const SizedBox(height: 24),
            for (int i = 0; i < question.answers.length; i++)
              Padding(
                padding: const EdgeInsets.only(bottom: 12),
                child: FilledButton.tonal(
                  style: FilledButton.styleFrom(
                    backgroundColor: _colorFor(i),
                    foregroundColor: _colorFor(i) == null ? null : Colors.white,
                    padding: const EdgeInsets.all(16),
                  ),
                  onPressed: () => _pick(i),
                  child: Text(question.answers[i]),
                ),
              ),
            if (_answered && !_isLast)
              FilledButton(
                onPressed: _next,
                child: const Text('Next'),
              ),
          ],
        ),
      ),
    );
  }
}