Flutter Interview Questions

Here’s a list of top Flutter questions that are frequently asked.

Q1.  Is Flutter an open-source?

A1.  Yes, Flutter is a 100% open-source software development kit.

Q2.  What are flutter widgets?

A2.  Widgets are the core building blocks that create a user interface. Widgets basically describe how our application should look.

Q3.  What are the main differences between Stateful widgets and Stateless widgets?

A3.  A stateful widget is a widget that can be changed, and the user can interact, i.e., it is mutable. A stateless widget is a widget that never changes, i.e., it is immutable.

Q4.  What is pubspec.YAML file?

A4.  A file that contains all the dependencies and metadata is pubspec.yaml. It is one of the most important files in Flutter.

Q5.  Give the best IDEs that can be used for flutter development.

A5.  Following are the list of IDEs compatible with Flutter:

• Android Studio
• IntelliJ
• VS Code

Q6.  What are the main differences between React Native and Flutter?

A6.  React Native works on JavaScript, but Flutter is entirely based on dart language. In terms of pf performance, Flutter is way ahead of React Native as developers are preferring the former over the later.

Q7.  Give some popular applications made using Flutter.

A7.  The following are the names of some popular applications made using Flutter:

• Google Ads
• Alibaba
• Reflect
• Birch Finance
• Insight Timer

Q8.  Could we use Flutter for heavy application development?

A8.  Flutter offers high-performance application development, but many developers say that Flutter is not ideal for heavy applications such as e-commerce applications.

Q9.  What is meant by Await?

A9.  It is a keyword that is a part of asynchronous programming. It means to wait for the function to run asynchronously and then continue to the next code line.

Q10. What is meant by Async?

A10. For any function that needs to be run asynchronously (I.e., not simultaneously), we use the Async keyword. With async, we need to wait to get a result.

Q11. What is meant by the Future?

A11. A Future is a value or error that might be thrown our way sometime in the Future. It is an important part of asynchronous programming.

Q12. What is the Hot Reload feature?

A12. A hot reload is a quicker method of reloading the state of a Flutter application. It is one of the most beneficial features that Flutter has to offer. If one does not want to lose the state of the application but wants to see whether the changes are made in the application or not, a hot reload is a perfect solution.

Q13. Give the main points of differences between Hot Reload and Hot Start?

A13. Hot reload faster than Hot restart as the hot restart destroys the state and rebuilds it. A hot reload saves both the time and energy of the developer.

Q14. What are the differences between main() and runApp()?

A14. main() is an absolutely essential function in dart language; it is the entry point to any application. At the same time, runApp() is a method that needs to be called in order to start the framework.

Q15. What is meant by @required?

A15. The @required is a keyword that gives a warning when the parameter necessary for a class is given a null value. It comes in handy when one needs some parameters to have some value.

Q16. What are the keys to Flutter?

A16. Keys are unique identifiers, and they preserve the state of an application.

Q17. What are the packages?

A17. Packages can be described as sharable libraries that help in organizing a set of classes and interfaces.

Q18. What are plugins?

A18. Plugins are used for adding additional features to a Flutter application.

Q19. Is Flutter limited to mobile application development only?

A19. No, with Flutter, one can create beautiful and powerful web applications as well with just a single code-base.

Q20. Why is Flutter so unique and in-demand?

A20. Given below are the reasons why Flutter so unique and in demand:

• Single code-base, multiple platforms
• Cost-efficient
• Takes less time
• Powerful application performance
• 100% open-source

Q21. Who developed Flutter?

A21. Google developed Flutter.

Q22. Why should we use the Dart programming language?

A22. Following are the reasons why the Dart programming language used should be encouraged:

• It is an object-oriented, garbage collected and class-based programming language.
• The syntax is very similar to that of C/C++.
• Supports cross-platform development.

Q23. Can we integrate Flutter mobile application development with a third-party?

A23. Yes, integration with a third-party is possible in the case of Flutter. The most popular third-party packages integrated with Flutter applications are Flutter_launcher_icons, cached_network_image and so on.

Q24. List a few benefits of using Flutter for application development.

A24. Given below are some benefits of using Flutter for application development:

• Hot reload
• High performance
• Quick development
• Less money consuming
• Cross-platform

Q25. Is Flutter only limited for User-Interface?

A25. Flutter is mainly used for User-Interface, but with the state management technique, one can create a fully functional mobile application.

Q26. Which database is best for Flutter?

A26. Firebase is the best database for Flutter.

Q27. Is Flutter a framework?

A27. No, Flutter is not merely a framework. Instead, it is a full software development kit (SDK) for developing a fully functional mobile application.

Q28. What is meant by a spacer widget?

A28. A spacer widget makes an empty spacer used to adjust the space between widgets in a Flex container.

Q29. What is meant by vsync?

A29. vsync is short for vertical sync. It helps to keep track of the screen so that Flutter does not render the animation when the screen is no longer being displayed. 

Q30. Give the main points of difference between SizedBox and Container.

A30. SizedBox is simpler than Container as the former is a box with a specified size, but Container contains child widgets that help in some styling property. One can make a SizedBox const, but that is not possible with Container. 

Q31. What is Navigator?

A31. Navigator is used for managing routes in the Flutter application. It can push and pop routes (just like in stacks) for screen to screen transition.

Q32. What is meant by Flutter Inspector?

A32. Flutter Inspector is a tool that is used for envisioning and investigating widget trees in Flutter. It is a very powerful and beneficial tool.

Q33. What is Visibility Widget?

A33. Visibility Widget controls the visibility of a widget. It helps in removing the widget until it is needed on the screen.

Q34. What are mixins?

A34. When it is needed to reuse a class code in multiple class hierarchies, mixins come into play. With mixins, we can achieve reusability.

Q35. What is a ticker?

A35. A ticker can be described as a class which calls its callback once per animation.

Q36. What is meant by AspectRatio?

A36. AspectRatio is a ratio between the height and the width of a box.

Q37. Give the main point of difference between mainAxisAlignment and crossAxisAlignment.

A37. MainAxisAlignment is the items that are aligned on that axis, and crossAxisAlignment is items that are aligned on the other axis. 

Q38. What is meant by a widget tree?

A38. A widget tree is a combination of nested widgets. It basically contains other widgets.

Q39. What is testing in Flutter?

A39. Testing is a process of testing an application for its consistency, functionality and, usability.

Q40. What is setState() in Flutter?

A40. A setState() is responsible for notifying the framework that the state of the object has changed.

Q41. What is the best state management in Flutter?

A41. Following are the best state managements in Flutter:

• Redux
• MobX
• Flutter Hooks

Q42. What is @override in Flutter?

A42. @override is provided by dart programming language. It is a keyword. It just points out that the function is also defined in an ancestor class. If you provide a method that also existed in a class we're extending, you should add @override.

Q43. What is meant by a Scaffold?

A43. Scaffold helps in creating a base page for Flutter Application. It will give a basic design, structure and color scheme for the User-Interface.

Q44. What is SingleTickerProviderStateMixin in Flutter?

A44. When we add SingleTickerProviderStateMixin, it tells Flutter that there is some animation in this widget, and this widget needs to be notified about the animation frames of Flutter.

Q45. What is AppBar in Flutter?

A45. AppBar is Flutter adds a top-up bar to a Flutter application. It also has various properties. 

Q46. What is meant by RaisedButton?

A46. A RaisedButton is a button that gives it a background color and a little hover effect. 

Q47. What is onPressed() in Flutter?

A47. onPressed() is a function in Flutter that is executed when the button is pressed. It is used for giving directions when a specific button is pressed.

Q48. What is “this” in Flutter?

A48. "this" is a keyword in Flutter, which is used to specify which variable is being discussed when there is scooping in the class.

Q49. What is build() in Flutter?

A49. The build() is a method that returns the widgets (from the widget tree) that should be rendered onto the screen.

Q50. What is meant by the list?

A50. It is a group of data. It is an array's alternative for dart language. Lists are created with the help of square brackets.