Flutter Developer Interview Questions & Answers

Preparing for a Flutter Developer interview? Here are some essential questions and their answers.

1. Flutter Basics & Dart Language

What is Flutter, and why did you choose it for app development?

Flutter is an open-source UI toolkit developed by Google for building natively compiled applications for mobile, web, and desktop from a single codebase.

Difference between StatefulWidget and StatelessWidget

class MyStatelessWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text("I never change!");
  }
}
    

2. State Management

When would you use GetX over Provider or BLoC?

- GetX: Best for small projects, minimal boilerplate.
- Provider: Good for dependency injection.
- BLoC: Best for large apps with structured state management.

3. Performance Optimization

How do you reduce widget rebuilds?

Use const widgets, ValueKey, and optimize ListView.builder.

4. API Integration & Database

How do you handle API calls in Flutter?

final dio = Dio();
Future<void> fetchData() async {
  final response = await dio.get("https://api.example.com/data");
  print(response.data);
}
    

5. Navigation & Routing

Explain Navigator 1.0 vs Navigator 2.0

- Navigator 1.0: Uses push/pop.
- Navigator 2.0: Declarative navigation.

6. Real-world Scenario-Based Questions

How did you handle a Flutter app crash in production?

Used Firebase Crashlytics and try-catch blocks for debugging.

7. Testing & CI/CD

What are the different types of testing in Flutter?

test("Addition test", () {
  expect(2 + 2, 4);
});
    

8. Flutter for Different Platforms

How do you handle platform-specific code in Flutter?

static const platform = MethodChannel('com.example/native');
Future<String> getNativeData() async {
  return await platform.invokeMethod('getBatteryLevel');
}
    

9. Design & UI/UX

What is CustomPainter in Flutter?

class MyPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()..color = Colors.blue;
    canvas.drawCircle(Offset(size.width / 2, size.height / 2), 40, paint);
  }
  @override
  bool shouldRepaint(CustomPainter oldDelegate) => false;
}
    

10. Problem-Solving & DSA

Find the first non-repeating character in a string

String firstNonRepeatingChar(String s) {
  Map count = {};
  for (var c in s.split('')) count[c] = (count[c] ?? 0) + 1;
  return s.split('').firstWhere((c) => count[c] == 1, orElse: () => '');
}
    

These questions will help you ace your Flutter Developer interview! Good luck! 🚀