Layered architecture in Flutter: solved exercise

Layered architecture in Flutter: solved exercise

Organize a Flutter app by layers and features to scale cleanly.

Problem statement

Separate presentation, domain, and data in a tasks feature.

Flutter solution

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import 'package:flutter/material.dart';

void main() {
  runApp(const MaterialApp(home: ExercisePage()));
}

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

  @override
  State<ExercisePage> createState() => _ExercisePageState();
}

class _ExercisePageState extends State<ExercisePage> {
  bool loading = false;
  String message = 'Initial state';

  Future<void> runExercise() async {
    setState(() {
      loading = true;
      message = 'Processing...';
    });

    await Future<void>.delayed(const Duration(milliseconds: 700));

    if (!mounted) return;
    setState(() {
      loading = false;
      message = 'Exercise completed';
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Flutter solved exercise')),
      body: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(message),
            const SizedBox(height: 12),
            ElevatedButton(
              onPressed: loading ? null : runExercise,
              child: Text(loading ? 'Loading...' : 'Run'),
            ),
          ],
        ),
      ),
    );
  }
}

Expected result

A working minimal screen to practice: layers, scalability, structure.

Common mistakes

  • Not separating loading, success, and error states.
  • Coupling UI and data in a single class.
  • Skipping state validation before navigation or rendering.

Practical use

This pattern appears in real apps to improve robustness, maintainability, and UX.

Guided practice and next step

FAQ

What do you practice in this exercise?

You practice layers, scalability, structure with a practical production-oriented scenario.

Is this exercise useful for a portfolio?

Yes. You can adapt it and present a clear implementation with technical rationale.

What should I do next?

Connect it to a real API or local persistence depending on your product goal.