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Flutter inteview questions for you

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This repository contains a list of interview questions for Flutter developers. The questions are divided into different categories. The questions are not limited to the ones mentioned here. You can add more questions to the list. The questions are not specific to any company or organization or any experience level. The questions are based on the contribution of the community. You can contribute to this repository by adding more questions to the list.

Table of Contents

General Questions

1.  Give a brief introduction about yourself.
Your name, your educational background, your experience, your hobbies, etc.
2. What are your strengths and weaknesses?
3. What are your hobbies, and what do you do in your free time?
4. What do you know about our company, and why do you want to work here?
5. Why did you choose this career?
6. Where do you see yourself in 5 years?
7. Why should we hire you?
8. Why did you leave your last job, or why are you looking for a new job?
9. How do you define agile development or What is agile development?
10. Suppose you are working on a project and you have to deliver a feature in 2 weeks. As a team leader, how will you manage the project? What are the things you will keep in mind?
11. Suppose you got a bug in your project, How do you approach it?
12. How do you know if a feature is ready to be released?
13. How do you know which architecture to use for a project?
14. What do you understand by scalability? How do you achieve scalability in your project?
15. How do you handle conflicts in your team?
16. How do you handle communication gap in your team when you are working remotely or in a different time zone?
17. Have you ever worked in a team where you had to work with people from different cultures? If yes, then how did you handle it?
18. Have you deployed your app on play store or app store? If yes, then how did you do it? What are the challenges or difficulties you faced while deploying your app? How did you overcome them?
19. What do you think is the area where you need to improve yourself?

OOP Questions

1. What do you understand by OOPs?
2. What are the features of OOPs?
3. Is dart a pure object-oriented programming language?
4. Types of modifiers in dart? What do you understand by each modifier?
5. What do you understand by abstraction? 
6. What is the difference between interface and abstract class? When to use which?
7. What do you understand by encapsulation? Explain with an example.
8. What do you understand by inheritance and how is it achieved in dart? Explain with an example.
9. What do you understand by polymorphism and how is it achieved in dart? Explain with an example.
10. What is difference between final and const keyword in dart?
11. Does dart support multiple inheritance?
12. What is the difference between Array and List in dart?
13. What is singleton class? How do you create a singleton class in dart?

Programming Concept Questions

1. What is the difference between synchronous and asynchronous programming? How do you handle asynchronous programming in dart?
2. Explain SOLID principles.
3. What do you understand by the term "code smell"?
4. What is the difference between a function and a method?
5. What do you understand by clean code? How do you write clean code?
6. Is dart a compiled or interpreted language?
7. Do you know any other programming language apart from dart? If yes, then what are the differences between dart and that language?
8. What do you understand by Dependency Injection? How many types of dependency injection are there? Have you heard about Inversion of Control? If yes, then what is the difference between Dependency Injection and Inversion of Control? 
9. How do you handle dependency injection in dart? Explain with an example.
10. How do you handle cyclic dependency? 
11. How many design patterns do you know? Explain them.
12. What do you understand by null safety? How do you handle null safety in dart? How many types of null safe operators are there in dart?
13. What is TDD? How do you implement TDD in your project?
14. Types of testing, Is it necessary to write test cases for every feature? If yes, then why?
15. Why should we write test cases? What are the advantages of writing test cases?
16. Sometimes there is a need to write a code which is not reusable. How do you handle it?
17. Suppose you deployed your app on play store or app store. After some time, you got a bug in your app in production but not in development. How do you approach it?
18. Do you think it is a good practice to write comments in your code? If yes, then why? If no, then why?

19. What do you understand by caching? How do you handle caching in your project?
20. What is an API? REST API?
21. What is difference between REST API and SOAP API?
22. Why do we use POST requests when we can pass data in GET requests as well?
23. What is the difference between PUT and PATCH requests?
24. Suppose you made a POST request to an API and you got a response 201. What does it mean?
25. What is the difference between HTTP and HTTPS? Which one is faster and why?
26. Should you store your API keys in your code? If yes, then why? If no, then why?
27. Have you used graphql in your project? How is it different from REST API?
28. Difference between 401 and 403 status code?

Flutter and Dart Questions

29. What is Dart and Flutter?
30. What are the advantages of using Flutter, over native app development, along with the disadvantages?
31. Does flutter provide native performance on all platforms?
32. How does flutter achieve native performance?
33. What do you understand by hot restart, and hot reload?
34. How does hot reload work?
35. Explain JIT (Just In Time) and AOT (Ahead Of Time) compilation. How does JIT and AOT compilation work in flutter?
36. What do you understand by the term "widget tree"?
37. What is BuildContext?
38. What is the difference between StatelessWidget and StatefulWidget? How do you know which one to use for a particular feature?
39. What is State management? How do you handle state management in flutter?
40. What are the different types of state management in flutter? How many of them are you familiar with? Which one do you prefer and why?
41. Explain the difference between setState() and setState((){}).
42. Can you use setState() in initState() method? If yes, then how? If no, then why?
43. Explain Keys in flutter. What are the different types of keys in flutter? How do you use keys in flutter? When do you use keys in flutter?
44. Are you familiar with the concept of "Inherited Widget"? If yes, then explain it.
45. You got an error 'setState() or markNeedsBuild() called during build'. Why do you think this error occurred? How do you handle it?
46. Can you get the context of a widget outside the build method? If yes, then how? If no, then why?
47. How do you handle the dependency changes in a widget, when the state of a widget changes?
48. Suppose you have a list of widgets and you want to update the state of a particular widget in the list. How do you do it?
49. How do you handle back button press in flutter?
50. What do you understand by type casting? How do you handle type casting in flutter? Explain with an example.
51. You got an error "The method 'xxx' isn't defined for the class 'xxx'". How do you handle it?
52. How do you handle long running tasks in flutter? Explain with an example.
53. Do you need permission to access the internet in flutter? If yes, then how do you handle it? If no, then why?
54. How do you handle localizations in flutter?
55. What do you understand by the term "responsive design"? How do you handle responsive design in flutter?
56. How do you handle network calls in flutter? What packages do you use for network calls?
57. Wh
58. Have you implemented any payment gateway in your project? What are the challenges you faced while implementing it? How did you overcome them?
59. How do you handle the error in network calls in flutter?
60. Have you used environment variables in your project? If yes, then how do you handle it?
61. Have you used product flavors in your project? If yes, then how do you handle it?

Streams Questions

1. What are streams in dart? How many types of streams are there in dart? How do you handle streams in flutter?
2. What is the difference between Future and Stream?
3. Suppose you have a list of Future objects and you want to wait for all the futures to complete. How do you do it?
4. Explain FutureBuilder and StreamBuilder. How do you use them?
5. How do you handle socket programming in flutter, if you have to implement a chat application?
6. Since dart is a single threaded language, how do you handle multiple tasks in dart?
7. Using dart, how do you handle multiple tasks in parallel?

Google Maps Questions

1. Have you used Google Maps in your project? How do you create a mark certain area on the map? 
2. Can you create a custom marker on the map? If yes, then how? If no, then why?
3. What do you understand by clustering in Google Maps? How do you handle clustering in Google Maps?
4. How do you get the current location of the user? How do you get the location of the user when the user moves?
5. Do you know any other map packages apart from Google Maps? If yes, then what are the differences between Google Maps and that package?

Animations Questions

1. What do you understand by the term "animations"? How do you handle animations in flutter?
2. Explain the difference between Implicit and Explicit animations.
3. Suppose you want to animate a widget from one position to another position. How do you do it?
4. What do you understand by the term "tween"? How do you use tween in flutter?
5. What do you understand by the term "curve"? How do you use curve in flutter?
6. What is SingleTickerProviderStateMixin? Why do we use it?
7. How do you handle complex animations in flutter while maintaining the performance?
8. Have you used Hero animations in your project? If yes, what do you think of it? Do you think it is a good practice to use Hero animations in your project? If yes, then why? If no, then why?
9. How do you handle page transitions in flutter?

Bloc Questions

1. What do you understand by the term "bloc"? Why do we use bloc while we can use setState() to update the state of a widget?

The term "bloc" refers to a business logic component or block. It is a design pattern used for managing application state and separating business logic from the UI layer. We use bloc instead of directly using setState() to update the state of a widget for several reasons:

  • Separation of Concerns: Bloc promotes a clear separation of business logic and UI, making the codebase more maintainable and easier to understand. It allows for better organization of code by keeping the business logic separate from the UI-related code.

  • Reusability: By encapsulating the business logic in blocs, you can reuse them across multiple widgets and screens, promoting code reusability. Blocs can be shared and used in different parts of the application, reducing code duplication.

  • Testability: Blocs can be easily tested since they are decoupled from the UI layer. This enables more effective unit testing, as you can test the business logic independently of the UI components. By writing tests for blocs, you can ensure the correctness and reliability of your application's state management.

  • Scalability: The bloc pattern helps manage complex state management and prevents the codebase from becoming messy and difficult to maintain. As your application grows in size and complexity, using blocs provides a structured and scalable approach to handle state changes and business logic. It allows for better organization and modularity, making it easier to add new features or modify existing ones.

In summary, the use of blocs in state management offers benefits such as separation of concerns, reusability, testability, and scalability. It provides a structured and organized way to handle application state and business logic, resulting in a more maintainable and robust codebase.

2. Is it a good practice to use bloc in a small project? If yes, then why? If no, then why?

Using bloc pattern in a small project can be subjective and depends on several factors. Here are some points to consider:

Yes, it's a good practice to use bloc in a small project

  • Scalability: If you anticipate that your small project might grow in complexity and size over time, using the bloc pattern can provide a structured approach to state management from the beginning, making it easier to scale and maintain the codebase as it evolves.
  • Code organization: The bloc pattern promotes a separation of concerns, even in small projects. This can result in cleaner, more organized code, making it easier to understand and maintain.
  • Reusability: Even in a small project, if you foresee the potential need to reuse certain logic or components across different screens or widgets, implementing blocs can help enhance code reusability.

No, it may not be necessary in a small project

  • Simplicity: If your small project has straightforward state management needs and the logic is not too complex, using the bloc pattern might introduce unnecessary overhead. In such cases, a simpler state management approach like using Flutter's built-in setState() method might suffice and be more straightforward.
  • Development time: Implementing the bloc pattern requires additional setup and boilerplate code. If time is a constraint and your small project has a tight deadline, opting for a simpler state management approach could be more efficient.

Ultimately, the decision to use bloc in a small project depends on the project's specific requirements, expected growth, and complexity. Consider the trade-offs and choose the approach that best aligns with the project's needs and development constraints.

3. Explain state, event, and bloc.

State: State represents the current condition or data of a widget or an application. It defines what the UI should display based on the data it holds. For example, a state could be a loading state, an error state, or a data-loaded state.

Event: An event represents an action or a trigger that occurs in the application. It can be user interaction, network responses, timers, or any other action that can cause a state change. Events are dispatched to the bloc to inform it of a state change request.

Bloc: A bloc (business logic component) is responsible for managing the state of an application or a widget. It listens to events, processes them, and emits new states accordingly. A bloc is the central component that handles the business logic and acts as a bridge between events and states.

4. Can you explain the difference between bloc and cubit?

The key difference between bloc and cubit lies in their level of complexity and flexibility:

Bloc: Bloc provides a more comprehensive and flexible approach to state management. It involves defining separate classes for events, states, and the bloc itself. Blocs handle complex state management scenarios, asynchronous operations, and can be easily tested. Blocs are suitable for medium to large-scale applications.

Cubit: Cubit (short for "business logic unit") is a simplified version of bloc with less boilerplate code. It combines the functionality of events and states into a single class. Cubits are suitable for simpler state management scenarios and smaller projects where the additional complexity of bloc is not required.

The choice between bloc and cubit depends on the complexity and scalability needs of the project.

5. How can you access the bloc from a widget?

To access the bloc from a widget, you can use the BlocProvider.of<T>(context) method, where T represents the type of the bloc you want to access. Make sure that the widget's parent tree includes a BlocProvider widget that provides the desired bloc. The context parameter is the widget's build context.

Example usage:

final bloc = BlocProvider.of<MyBloc>(context);

This allows you to access the bloc instance and use its methods or access its state within the widget.

Remember to import the necessary dependencies and ensure that the correct context is used for accessing the bloc.

6. Are you familiar with the concept of "bloc observer"? If yes, then explain it.

Yes, a bloc observer is a feature provided by the bloc library that allows observing and intercepting bloc events and state changes. It provides hooks to monitor and react to various bloc-related activities, such as when events are dispatched, states change, or errors occur.

By extending the BlocObserver class and registering it using Bloc.observer, you can listen to and respond to different lifecycle events of blocs, enabling features like logging, analytics, or UI updates based on state changes. The observer receives notifications and can perform custom actions accordingly.

The BlocObserver class provides several methods that can be overridden to handle different events, including onEvent, onTransition, and onError. These methods allow you to inspect and react to the different stages of bloc behavior.

Using a bloc observer can be beneficial for debugging, performance monitoring, or gathering analytics data related to your application's state management.

To implement a custom bloc observer, you can create a class that extends BlocObserver and override the desired methods. Then, register your custom observer using Bloc.observer = MyBlocObserver(); in your application's entry point.

7. How do you handle communication between blocs?

Communication between blocs can be achieved through various approaches:

  • Using a Shared Bloc: You can create a dedicated bloc responsible for managing shared state or data between multiple blocs. Other blocs can communicate with this shared bloc to access or update the shared data.

  • Using Events: Events can be used to trigger actions in one bloc based on specific conditions in another bloc. Blocs can dispatch events that are listened to by other blocs, allowing communication between them.

  • Using Bloc Libraries: Some bloc libraries provide built-in mechanisms for inter-bloc communication, such as the flutter_bloc library's BlocListener or BlocConsumer widgets. These widgets can listen to state changes in multiple blocs and trigger corresponding actions.

The specific approach depends on the complexity of the communication needs and the libraries or patterns being used.

8. You got an error "BlocProvider.of() called with a context that does not contain a Bloc of type xxx". How do you handle it?

When encountering the error "BlocProvider.of() called with a context that does not contain a Bloc of type xxx," you can follow the following steps to handle it:

  1. Verify Widget Tree: Make sure that you have wrapped the widget tree with a BlocProvider widget that provides the required bloc instance. The BlocProvider should be placed above the widget where you are trying to access the bloc.

  2. Check Bloc Type: Double-check that the bloc instance you are trying to access matches the type specified in BlocProvider.of<T>(context). The type T should correspond to the type of the bloc you are trying to access.

  3. Correct Context Usage: Ensure that you are accessing the bloc using the correct context object. Typically, this is done within the widget's build method or other relevant context scope. Ensure that the context used to access the bloc is associated with the BlocProvider widget.

  4. Placement of BlocProvider Widget: If the error persists, double-check the placement of the BlocProvider widget. Confirm that it is correctly instantiated and provided to the widget tree. Ensure that the BlocProvider is placed at an appropriate level in the widget tree to ensure the availability of the bloc throughout the desired scope.

By following these steps, you can resolve the error and successfully access the bloc instance from the widget.

9. Does BlocBuilder rebuild the widget every time the state changes?

Yes, BlocBuilder rebuilds the widget every time the state changes. It listens to state changes in the associated bloc and triggers a rebuild of the builder function whenever a new state is emitted. This allows the widget to reflect the updated state and update its UI accordingly.

However, BlocBuilder provides an optional buildWhen parameter that allows you to define custom conditions for whether the builder function should be called and the widget should rebuild. By providing a buildWhen function, you can control when the widget should update based on specific state conditions.

The buildWhen function takes the previous state and the current state as input and returns a boolean value. If the buildWhen function returns true, the builder function will be called and the widget will rebuild. If buildWhen returns false, the builder function will not be called, and the widget will not rebuild.

This optional parameter provides a way to optimize performance by avoiding unnecessary rebuilds when the state changes but the UI doesn't need to be updated. It allows you to conditionally rebuild the widget based on specific state conditions.

Example usage:

BlocBuilder<MyBloc, MyState>(
    builder: (context, state) {
    // Widget build function
    },
    buildWhen: (previousState, currentState) {
    // Custom condition to control rebuilds
    return currentState.data != previousState.data;
    },
);

In the above example, the widget will only rebuild if the data property of the currentState differs from the data property of the previousState.

10.  Can you explain the difference between BlocBuilder and BlocConsumer?

The main difference between BlocBuilder and BlocConsumer lies in their usage and the level of control they provide over widget updates:

  • BlocBuilder: BlocBuilder is suitable when you want to rebuild a widget in response to state changes. It provides a builder function that is called whenever the state changes, allowing you to update the UI based on the new state. It gives you more control over when and how the widget should rebuild.

  • BlocConsumer: BlocConsumer combines the functionality of BlocBuilder and BlocListener in a single widget. In addition to rebuilding the widget on state changes, it also allows you to react to state transitions and execute specific callbacks. It provides builder and listener functions, where the builder is called on state changes, and the listener is called when state transitions occur.

Choose between BlocBuilder and BlocConsumer based on your specific needs for handling state changes and state transitions. If you only need to rebuild the widget on state changes, BlocBuilder provides a more focused approach. If you require additional control over state transitions and want to execute specific callbacks, BlocConsumer offers a more comprehensive solution.

11.  Can you rebuild a widget conditionally when the state changes? If yes, then how?

Yes, you can rebuild a widget conditionally when the state changes by utilizing the buildWhen parameter of BlocBuilder. The buildWhen function allows you to define custom conditions under which the builder function should be called and the widget should rebuild.

The buildWhen function takes the previous state and the current state as parameters and returns a boolean value indicating whether the builder function should be called. By specifying appropriate conditions in the buildWhen function, you can control when the widget should update and rebuild its UI.

Example usage:

BlocBuilder<MyBloc, MyState>(
    builder: (context, state) {
    // Widget build function
    },
    buildWhen: (previousState, currentState) {
    // Custom condition to control rebuilds
    return previousState.data != currentState.data;
    },
);

In the above example, the widget will only rebuild if the data property of the currentState differs from the data property of the previousState. By specifying the appropriate condition in the buildWhen function, you can conditionally update the widget based on specific state changes.

12.  Suppose you have to make a network call and you want to show a loading indicator while the network call is in progress. How do you handle the state of the widget?

To handle the state of the widget while making a network call and showing a loading indicator, you can utilize the bloc pattern along with different states to represent the different stages of the network request. Here's an example approach:

  1. Define a LoadingState, SuccessState, and ErrorState to represent the different states of the widget.

  2. Initialize the state of the widget as LoadingState and display a loading indicator.

  3. Dispatch an event to the bloc to initiate the network request.

  4. While the request is in progress, the bloc can emit the LoadingState, and the widget can update its UI accordingly to show the loading indicator or any other relevant UI elements.

  5. Upon successful completion of the network request, the bloc can emit the SuccessState, and the widget can display the desired data or update the UI based on the success state.

  6. If an error occurs during the network request, the bloc can emit the ErrorState, and the widget can display an error message or handle the error appropriately.

By managing the state through the bloc, you can handle the different stages of the network call and update the UI of the widget accordingly. This approach allows for a cleaner separation of concerns and makes it easier to manage the state of the widget during network requests.

Firebase Questions

1. What is Firebase? How do you use Firebase in your project?

Firebase is a comprehensive platform provided by Google for developing web and mobile applications. It offers a wide range of services and features that help developers build, scale, and manage their applications more effectively. Firebase provides solutions for various aspects of app development, including authentication, real-time database, cloud storage, hosting, cloud functions, and more.

How to use Firebase in your project?

To use Firebase in your project, follow these general steps:

  1. Create a Firebase project: Start by creating a new project in the Firebase console (https://console.firebase.google.com) and give it a name. This project will serve as the container for your app and its associated Firebase services.

  2. Add Firebase to your app: Depending on the platform you are targeting (iOS, Android, web), you will need to add the appropriate Firebase SDK to your project. The Firebase documentation provides detailed instructions for adding Firebase to your specific platform.

  3. Configure Firebase services: Enable and configure the Firebase services you want to use in your app. This may include services like Authentication, Real-time Database, Cloud Firestore, Cloud Storage, etc. Each service will have its own set of configuration options and usage guidelines.

  4. Integrate Firebase APIs: Once the Firebase SDK is added and services are configured, you can start integrating Firebase APIs into your app's code. This may involve using authentication APIs for user management, database APIs for data storage and retrieval, cloud functions for serverless computing, etc.

  5. Test and deploy your app: Test your app to ensure that the Firebase integration is working correctly. You can use Firebase's built-in testing tools or third-party testing frameworks for this purpose. Once your app is ready, you can deploy it to your desired platform, such as an app store, web server, or Firebase hosting.

  6. Monitor and optimize: Firebase provides various monitoring and analytics tools that allow you to track app performance, user engagement, and other metrics. Utilize these tools to gain insights into your app's usage and make optimizations as needed.

Remember to consult the official Firebase documentation (https://firebase.google.com/docs) for detailed instructions and specific usage guidelines for each Firebase service.

2. Is it a good practice to use Firebase in a small project? If yes, then why? If no, then why?

Whether or not it is a good practice to use Firebase in a small project depends on the specific needs and requirements of the project. Here are some considerations:

Yes, it can be a good practice:

  • Rapid Development: Firebase offers a suite of ready-to-use services that can accelerate development in a small project. Its ease of integration and intuitive APIs can help you quickly implement common functionalities such as user authentication, database storage, and cloud functions.

  • Scalability: Even though a small project may have a limited initial scope, if there is a possibility of future growth or an expected increase in user base, Firebase can provide a scalable solution. It offers a range of services that can easily scale with your app's needs, allowing you to focus on development rather than infrastructure management.

  • Cost Efficiency: Firebase has a flexible pricing model that caters to small projects. Many of its services offer free tiers with generous limits, making it a cost-effective choice for small-scale applications.

No, it may not be necessary:

  • Simplicity: If your small project has straightforward requirements and can be efficiently implemented using basic libraries or frameworks, introducing Firebase may add unnecessary complexity. Assess whether the project truly needs the additional features and services provided by Firebase.

  • Learning Curve: Using Firebase requires familiarity with its services and APIs. If the project timeline is tight and the development team is not experienced with Firebase, it might be more efficient to utilize simpler alternatives that align with the team's existing skills.

In summary, the decision to use Firebase in a small project depends on the specific needs, future scalability requirements, development timeline, and the expertise of the development team. Consider the benefits, potential complexity, and costs associated with Firebase before deciding whether it is a good fit for your small project.

3. Name some of the Firebase services you have used in your project.

Firebase offers a wide range of services to enhance your app development process. Here are some of the Firebase services commonly used in projects:

  • Authentication: Firebase Authentication provides ready-to-use authentication methods, such as email/password, social logins, and phone number authentication, to handle user authentication and authorization.

  • Real-time Database: Firebase Real-time Database is a cloud-hosted NoSQL database that allows you to store and sync data in real-time across clients. It provides real-time synchronization, offline support, and automatic data syncing.

  • Cloud Firestore: Cloud Firestore is a flexible and scalable NoSQL document database that allows you to store, sync, and query data for your web, mobile, and server development. It offers rich querying capabilities and supports real-time updates.

  • Cloud Storage: Firebase Cloud Storage provides secure and scalable cloud storage for storing and serving user-generated content, such as images, videos, and files. It offers easy integration with other Firebase services.

  • Cloud Functions: Firebase Cloud Functions allows you to run serverless functions in response to events triggered by Firebase or HTTP requests. It enables you to extend the functionality of your app without managing server infrastructure.

  • Firebase Hosting: Firebase Hosting provides fast and secure web hosting for your static and dynamic web content. It allows you to deploy and serve your web app with a custom domain and SSL certificate.

  • Cloud Messaging: Firebase Cloud Messaging (FCM) enables you to send notifications and messages to targeted devices or user segments. It supports sending messages to iOS, Android, and web clients.

  • Analytics: Firebase Analytics provides insights into user behavior and app usage. It allows you to track user engagement, conversion rates, and user demographics to make data-driven decisions.

These are just a few examples of the services offered by Firebase. You can explore the Firebase documentation (https://firebase.google.com/docs) to learn more about each service and how to integrate them into your projects.

4. How do you handle push notifications in flutter? Can you explain the difference between local and remote notifications?

To handle push notifications in Flutter, you can utilize Firebase Cloud Messaging (FCM) or other third-party plugins. Here's an explanation of the difference between local and remote notifications:

  1. Local Notifications:

    • Local notifications are generated and displayed by the app itself without relying on a server or external service.
    • They are useful for sending reminders, alarms, or app-specific notifications to users.
    • Local notifications are scheduled and triggered within the app, and they do not require an internet connection or server interaction.
    • You can use plugins like the flutter_local_notifications or awesome_notifications package to implement local notifications in your Flutter app.

  2. Remote Notifications:

    • Remote notifications, also known as push notifications, are sent from a server or external service to the user's device.
    • They are used to deliver real-time updates, messages, or alerts to users even when the app is not actively running.
    • Remote notifications rely on a backend server, such as Firebase Cloud Messaging (FCM), to send the notifications to the intended devices.
    • When a remote notification is received, the system displays an alert, badge, or sound to notify the user.
    • In Flutter, you can use plugins like firebase_messaging to handle remote notifications and receive them in your app.

To implement push notifications in your Flutter app, you would typically follow these steps:

  1. Set up Firebase Cloud Messaging (FCM) by creating a Firebase project, configuring the necessary settings, and obtaining the necessary credentials.
  2. Integrate the firebase_messaging plugin in your Flutter project to receive remote notifications from FCM.
  3. Implement the handling of received notifications, including displaying them as alerts, updating the UI, or triggering specific actions based on the notification payload.
  4. Request the required permissions from the user to receive notifications, such as displaying system prompts for granting permission.
  5. Use the FCM API or the flutter_local_notifications package to schedule and display local notifications within your app.

By combining local and remote notifications, you can provide timely updates and information to your app users, both within the app and even when the app is not actively in use.

5. How do you authentication state changes in firebase in flutter?

Handling Authentication State Changes in Firebase with Flutter

Firebase Authentication provides various methods and callbacks to handle authentication state changes in Flutter. Here's how you can do it:

  1. Initialize Firebase Authentication:

    • Set up Firebase Authentication in your Flutter project by adding the necessary dependencies and configurations.
    • Create a Firebase project and enable the desired authentication providers.

  2. Implement Authentication Logic:

    • Use the firebase_auth package to authenticate users using different methods like email/password, phone number, Google Sign-In, etc.
    • Implement the necessary sign-in, sign-up, and sign-out methods in your Flutter app.

  3. Listen to Authentication State Changes:

    • Use the authStateChanges() method provided by the firebase_auth package to listen to authentication state changes.
    • This method returns a stream that emits the current user whenever there is a change in the authentication state.
    • Subscribe to this stream and update your app's UI based on the authentication state.

  4. Update UI based on Authentication State:

    • When the authentication state changes, update your app's UI accordingly.
    • For example, you can display different screens or widgets based on whether the user is authenticated or not.

  5. Handle Authentication Errors:

    • Handle authentication errors by catching and handling exceptions that may occur during the authentication process.
    • Show appropriate error messages to the user and provide them with the necessary instructions for resolving the issue.

By implementing the above steps, you can effectively handle authentication state changes in Firebase with Flutter. This allows you to control the user experience based on whether the user is authenticated or not.

Authentication Questions

1. How do you store the user credentials in flutter? What are the challenges you faced while implementing it?
2. Have you implemented social authentication in your project? If yes, then what are the challenges you faced while implementing it? How did you overcome them?
3. How do you handle different environments in social authentication? For example, you have to implement social authentication in both development and production environment. Do you use same credentials for both the environments?
4. Suppose you have implemented a JWT authentication in your project. How do you handle the token expiry?

Database Questions

1. What do you understand by persistent storage? How do you handle persistent storage in flutter?
2. Does flutter have any inbuilt database? If yes, then what is it? 
3. Have you used any database except key-value database in your project? If yes, which database did you use? What are the challenges you faced while implementing it? How did you overcome them?
4. How do you handle the database migrations in flutter?
5. What do you understand by the term "ORM"? Have you used any ORM in your project? If yes, then which ORM did you use? What are the challenges you faced while implementing it? How did you overcome them?

Testing Questions

1. What is testing? Why do we test our code?
2. How many types of testing are there in flutter? Explain them.
3. Do you know any other testing framework apart from flutter_test? If yes, then what are the differences between flutter_test and that framework?
4. Can you explain the difference between unit testing, widget testing, and integration testing?
5. What do you understand by the term "mock"? How do you use mock in flutter?
6. What is the key difference between mock and stub?
7. In flutter, how do you handle the asynchronous code in testing?
8. Are you familiar with the concept of "golden testing"? If yes, then explain it.

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