Chetu Flutter Interview Questions & Answers (2025)

Flutter Interview Questions & Answers – Chetu Company Preparation

Flutter is one of the fastest-growing frameworks for cross-platform app development. If you are preparing for an interview (like with Chetu Company), here’s a complete list of commonly asked Flutter Interview Questions & Answers to help you revise quickly.

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🔹 1. What is State Management in Flutter?

State management is how you manage and update the data that affects your UI. It ensures the UI automatically reflects changes in the application state.

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🔹 2. Why not always use setState?

• setState is simple but works only inside a widget.
• Not suitable for large apps as it causes unnecessary widget rebuilds.
• Difficult to scale and manage complex states.

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🔹 3. Package vs Plugin in Flutter

• Package: Reusable Dart code (e.g., http, provider).
• Plugin: Dart code + Native code (Java/Kotlin for Android, Swift/Obj-C for iOS) to access device features (e.g., camera, shared_preferences).

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🔹 4. What are Keys in Flutter?

Keys are used to preserve widget state when widgets are rebuilt, especially in lists. They help Flutter differentiate between widgets with the same type.

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🔹 5. Stream in Flutter (Key Points)

• Delivers asynchronous data over time.
• Can emit multiple values (unlike Future).
• Often used with StreamBuilder for real-time updates.

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🔹 6. Stateful vs Stateless Widget

• Stateless: UI does not change once built (static UI).
• Stateful: UI can change dynamically based on user interaction or data.

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🔹 7. Stateful Widget Lifecycle Explanation

1. createState → Creates state object.
2. initState → Called once, good for initialization.
3. didChangeDependencies → Called when dependencies change.
4. build → Builds the widget tree.
5. didUpdateWidget → Called when widget config changes.
6. setState → Triggers UI rebuild.
7. deactivate → Called when widget is removed from tree.
8. dispose → Cleanup before widget is destroyed.

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🔹 8. What is a Mixin in Flutter?

A way to reuse a class’s code in multiple class hierarchies. It allows adding functionality without inheritance.

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🔹 9. What is Extension in Flutter?

Extensions add new methods/properties to existing classes without modifying their source code.

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🔹 10. What is ChangeNotifier?

A simple class for state management that notifies listeners when notifyListeners() is called.

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🔹 11. What is Dependency Injection?

A design pattern where objects are provided their dependencies instead of creating them internally, improving reusability and testability.

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🔹 12. ListView vs ListView.builder (Key Points)

• ListView: Builds all items at once (good for small lists).
• ListView.builder: Builds items lazily (on demand), best for large/long lists.

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🔹 13. What is Tree Shaking?

A Dart/Flutter compiler optimization that removes unused code from the final build, reducing app size.

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🔹 14. Method Channel (Key Points)

• Used for communication between Dart and native code (Android/iOS).
• Works via a message-passing mechanism.
• Example: Accessing camera, Bluetooth, or sensors.

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🔹 15. Firebase Notifications in Flutter

Firebase Cloud Messaging (FCM) allows sending push notifications to Android/iOS apps using Firebase.

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🔹 16. How to Use Firebase Notifications?

1. Add firebase_core and firebase_messaging packages.
2. Initialize Firebase in main.dart.
3. Request notification permissions.
4. Use FirebaseMessaging.onMessage and FirebaseMessaging.onBackgroundMessage to handle notifications.

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🔹 17. Async & Await in Flutter

• async: Marks a function asynchronous, returns a Future.
• await: Pauses execution until a Future completes.

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🔹 18. MaterialApp vs Scaffold

• MaterialApp: Root widget, app-level configuration (theme, routes, navigation).
• Scaffold: Screen-level widget providing layout (AppBar, Drawer, FAB, BottomNav).

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🔹 19. About Flutter

Flutter is an open-source framework by Google for building cross-platform apps (Android, iOS, Web, Desktop) using a single codebase. It uses the Dart language and provides fast performance with a widget-based architecture.

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🔹 20. How to Remove Debug Banner in Flutter?

• Set inside MaterialApp:

MaterialApp(
  debugShowCheckedModeBanner: false,
);

• Or run app in release mode: flutter run --release.

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✨ Final Note:
These questions are commonly asked in Flutter interviews at Chetu and other companies. Revising them will boost your confidence and help you give crisp, clear answers.

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