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Flutter Interview Questions

Flutter is Google’s open-source UI toolkit for building cross-platform apps for mobile, web, desktop, and embedded devices from a single codebase.

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State management in Flutter refers to the way we manage the state of our application to ensure a responsive user interface. Various approaches exist for state management, including Provider, Riverpod, and Bloc.

Here’s a simple step-by-step guide using the Provider package:

  1. Add Dependency: Include the Provider package in your pubspec.yaml file.
  2. Create a Model: Define a class that holds your app's state.
  3. Wrap Your App: Use the ChangeNotifierProvider to wrap your main app widget.
  4. Consume State: Use Consumer widget to access the state in your widgets.

Example code snippet:

class Counter with ChangeNotifier {
  int _count = 0;
  int get count => _count;
  void increment() {
    _count++;
    notifyListeners();
  }
}

// In main.dart:
void main() {
  runApp(ChangeNotifierProvider(
    create: (context) => Counter(),
    child: MyApp(),
  ));
}
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In Flutter, everything is a widget. Widgets are the building blocks of a Flutter app’s user interface. They can be stateful (maintaining state) or stateless (not maintaining state).

Widgets work by composing small components into larger ones, allowing for a declarative UI approach:

  1. Stateless Widgets: Do not change over time. Example: Text, Icon.
  2. Stateful Widgets: Maintain state. Example: Checkbox, Slider.

Here’s a simple example of a Stateless widget:

class MyStatelessWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text('Hello, Flutter!');
  }
}
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Routing in Flutter refers to the process of navigating between different screens or pages within an app. Flutter provides a robust routing system to manage navigation effectively.

Here’s a step-by-step explanation of how routing works:

  1. Define Routes: You can define routes in the MaterialApp widget using the 'routes' property.
  2. Navigate: Use Navigator.push() to navigate to a new route and Navigator.pop() to return to the previous one.
  3. Named Routes: Use named routes for easier management of navigation.

Example code snippet:

void main() {
  runApp(MaterialApp(
    routes: {
      '/': (context) => HomeScreen(),
      '/details': (context) => DetailsScreen(),
    },
  ));
}

// Navigate to details screen:
Navigator.pushNamed(context, '/details');
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The pubspec.yaml file is a crucial part of any Flutter project. It serves as the configuration file for the Flutter app.

This file allows you to:

  1. Define Dependencies: Specify the packages your app needs to function, including both Flutter SDK and third-party packages.
  2. Set Metadata: Provide information such as the app name, description, version, and author.
  3. Assets Management: Declare any assets (images, fonts) your app will use.

Here's a basic example of a pubspec.yaml file:

name: my_flutter_app
version: 1.0.0

dependencies:
  flutter:
    sdk: flutter
  http: ^0.13.3

flutter:
  assets:
    - images/logo.png
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