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Flutter Interview Questions
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Last Updated: Jun 12, 2024

Flutter Interview Questions

Author Shaurya Singhal
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Ashwin Goyal
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18 Jun, 2024 @ 01:30 PM


Flutter is an open-source development kit. It was created by Google and is used to create cross-platform applications for Linux, Android, Windows, macOS, iOS, and Google Fuchsia using only one programming language and a single codebase. Flutter is one of the most commonly asked topics in a technical interview or a viva. So here is the list of the top forty Flutter interview questions. We will also be looking at the solutions for these Flutter interview questions.

Also Read About, Pandas Interview Questions and Operating System Interview Questions

Flutter Interview Questions

1. What is Flutter?

Flutter is an open-source development kit. It was created by Google and is used to create cross-platform applications for Linux, Android, Windows, macOS, iOS, and Google Fuchsia using only one programming language and a single codebase.

2. Is Flutter free to use?

Yes, Flutter is an open-source platform that is free to use. 

3. What are the best editors that can be used for Flutter Development?

The most popular IDE(Integrated Development Environments) used for flutter development are,

  • Visual Studio
  • Xcode
  • Android Studio
  • IntelliJ IDEA

4. What are the advantages of using Flutter?

Flutter is a very powerful tool. Let us look at some of the advantages of using Flutter.

  • Faster Development
  • Live and Hot Reloading
  • Cross-Platform Development
  • Good Community
  • Minimal Code
  • Documentation
  • UI Focused

5. Why does building the first Flutter application take time?

Building the first Flutter application requires more time because, on the first run, Flutter generates device-specific APK files which require a lot of time. 

6. Name famous companies that use Flutter?

Some of the most famous companies that use Flutter are,

  • Alibaba
  • Google Ads
  • Birch Finance
  • Tencent
  • Watermaniac
  • Reflectly
  • Coach Yourself

7. What is the latest released version of Flutter SDK?

The newest version of Flutter SDK is 2.10.4 and was released on 28 March 2022.

8. What are Database packages associated with Flutter?

The two most popular Database packages associated with Flutter are,

  • Firebase Database: It is used to access and manipulate cloud database
  • Sqflite Database: It is used to access and manipulate the SQLite Database

9. What is Dart?

Dart is one of the most popular languages that is used to create Flutter applications. It is a general-purpose language with C-style syntax. Dart is an open-source language developed by Google in 2011. 

10. What are the different types of Widgets present in Flutter?

There are only two types of Widgets in Flutter,

  • StatefulWidget: This Widget has mutable states.
  • StatelessWidget: This Widget doesn’t require mutable states.

11. What are Widgets?

Widgets are the UI components in Flutter used to describe the configuration of an element. Widgets are inspired by the components present in React.

12. What are the disadvantages of using Flutter?

Amid all the advantages of Flutter, there are a few disadvantages as well,

  • Flutter has a comparatively larger release size.
  • Flutter has a very limited number of third-party libraries available.
  • Flutter has a very limited complexity and cannot handle 3d modeling and game engines.
  • Although Flutter has a huge community, it still lacks constant support since it is a relatively new technology.
  • Not many developers prefer using Dart. Thus they avoid using Flutter as well.

13. What is the Controller Widget?

The controller is a Flutter widget that is used to compose, position, personalize, and decorate the child widgets. Only one child Widget can be added to the Container Widget.

14. What is the SnackBar Widget?

The SnackBar Widget is used to allow an application to pop up a message for a few seconds at the very bottom of the app interface.

15. What is the use of the Padding Widget?

The Padding Widget is used to wrap a Column, Row, or any other Widgets. The Padding Widget adds padding around the Child Widget.

16. What is the use of the SizedBox Widget?

The SizedBox Widget is used to alter the height and width of the Widgets.

17. What are the similarities between Future and Stream?

Two of the most common similarities between Future and Stream are,

  • Stream and Future are both asynchronous in nature.
  • Both Future and Stream have the same potential.

18. What are the differences between Future and Stream?

Two of the differences between Future and Stream are,

  • A Stream is a mixture of two or more Futures.
  • A Stream has multiple responses, whereas a Future has only one response.

19. What is a Future class in Flutter?

The Future class is used to address the computations that don’t finish right away. Regular functions return an outcome instantly, but the asynchronous functions return a Future, ultimately producing the outcome.

20. What is the Stream class in Flutter?

The functions use stream class to receive a sequence of events. The Done event will notify the listener that the end has been reached if all events have been emitted in Stream.

21. What is Tree Shaking in Flutter?

Tree Shaking is a technique that is used to remove all the unnecessary modules from the application during the build process. Tree Shaking can also be used to optimize the unnecessary code.

22. What are the different build models in Flutter?

There are three modes that can be used in Flutter while compiling the application.

  • Release
  • Debug
  • Profile

23. What is Profile Mode?

The Profile Mode in Flutter is used to measure the performance of an application. The Profile Mode is automatically deactivated on an emulator and a simulator. We can use the following code for the Profile Mode,

flutter run --profile

24. What is Debug Mode in Flutter?

The Debug Mode in Flutter is used to set up an application for Debugging on a physical device, simulator, or emulator. We can use the following code for Debug Mode.

flutter run --debug

25. What is Release Mode in Flutter?

The Release Mode in Flutter is used when the developer requires minimum footprint and maximum optimization. Similar to Profile Mode, Release Mode is not supported on emulators and simulators. We can use the following code for Release Mode,

flutter run --release

26. What is Hot Reloading in Flutter?

The Hot Reload in Flutter is used to add code to the Flutter application files while running the Dart Virtual Machine. 

27. What is Hot Restart in Flutter?

The Hot Restart in Flutter is used to reset the current state of an application to the initial state of the application.

28. What is the lifecycle of a Stateful Widget?

The lifecycle of Stateful Widgets includes the following steps,

  • createState
  • initState
  • didChangeDependencies
  • build
  • didUpdateWidget
  • setState
  • deactivate
  • dispose

29. What is the use of Spacer Widget in Flutter?

The Spacer Widget is used to create an empty adjustable space in Flutter. This empty space can be used to manage the distance between different containers present in the application.

30. What is Context in Flutter?

Context can be described as a handle to the location of a particular Widget in the Flutter application. Each Widget has a specific place inside the Widget Tree, and we can use Context to fetch this location.

31. What is the use of Flex class in Flutter?

The Flex class is used to list out all the children classes using a one-dimensional array. We can also control the placement of each children Widget using the Flex Widget.

32. Why do we use the HTTP package in Flutter?

HTTP stands for HyperText Transfer Protocol. It is an internet protocol that is used to fetch data from the internet safely. The HTTP package in Flutter is used to provide the application with a reliable and straightforward way to fetch data from the internet.

33. What is the architecture of a Flutter application?

The architecture of a Flutter application consists of three layers,

  • Upper Layer: The upper layer consists of the Dart code and the widgets. 
  • Flutter Engine: This is used to handle the display and formatting of the text.
  • Built-in Service: This layer is used to manage the plugins, event loops, and packages.

34. What are keys in Flutter?

Keys are like identifiers for the various Widgets, elements, and nodes. There are two types of Keys in Flutter, Local Keys and Global keys. The primary purpose of the Keys is to modify a Widget Tree composed of stateful Widgets. We can't modify a Widget tree that is only composed of stateless Widgets.

35. What is the use of Ticker in Flutter?

The Ticker class is used to determine how often an animation is refreshed in a Flutter application. We can send signals at a pre-determined frequency using the Ticker class. 

36. What is the use of Mixins?

As the Dart language doesn’t support multiple inheritance, the Mixins class is used to implement the concept of multiple inheritance in a Flutter application. We can also use the Mixin class to provide a few utility functions, such as the RenderSilverHelpers utility in Flutter.

37. What are the various kinds of Streams present in Flutter?

There are two types of Streams present in Flutter, namely.

  • Broadcast Streams: This Stream is used to deliver the events or the content directly to the subscriber. The subscribers can immediately start listening to the events as soon as they subscribe to the event. 
  • Single Subscription Streams: This Stream is used to deliver the events in a sequential manner. There is only one listener in a Single Subscription Stream.

38. What is Widget Testing in Flutter?

There are three types of Widget Testing supported by Flutter,

  • Widget Tests:  Using the Widget Tests, we can only test a single Widget at a time. 
  • Integration Tests: Using the Integration Tests, we can test all the critical flows present in the Flutter application.
  • Unit Tests: Using the Unit Tests, we can test a particular class or method present in the Dart code.

39. What are Packages in Flutter?

Packages are nothing but a collection of classes performing a similar task. We can use Packages in Flutter to save the hassle of rewriting a segment of code repeatedly. We can also use Packages to import new Widgets in a Flutter application.

40. What are the different types of parameters in Flutter?

There are two types of parameters in Flutter,

  • Optional Parameters: The Optional Parameters are defined at the end of a parameter list.
  • Required Parameters: The Required Parameters are the parameters that are required by a method or function to complete its code block.

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Tips and Tricks

To ace an interview, keep in mind the following tips,

  • Go through the list of previously asked Flutter interview questions.
  • Ask questions in an interview. If you are not clear about the question, ask the interviewer and get your doubts cleared.
  • It is not just about your technical skills in an interview. It is also about your communication skills.
  • Always keep in mind to take your time before answering the question. There is no rush to answer the question. Take your time and understand the question correctly.
  • And last but definitely not least, always keep in mind to learn something from the interview, and ask for feedback from the interviewer.

Key Takeaways

This blog contained a series of frequently asked Flutter interview questions. The blog also has sweet and to-the-point answers for the above-discussed Flutter interview questions.

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