21/Jul/2021 | 10 minutes to read
mobile-dev
Here is a List of essential Flutter Interview Questions and Answers for Freshers and mid level of Experienced Professionals. All answers for these Flutter questions are explained in a simple and easiest way. These basic, advanced and latest Flutter questions will help you to clear your next Job interview.
These questions are targeted for a Flutter developer. You must know the answers of these frequently asked Flutter technical questions to clear the interview. All these Flutter interview questions and answers are prepared by IT Professionals who have good industry experience.
1. What is flutter?
Flutter is an open-source UI toolkit or software development kit (SDK) developed by Google to build mobile, web and desktop applications from a single codebase. The main component of flutter includes:
2. What are the advantages of using Flutter?
Flutter comes with many advantages as:
3. What are the limitations of Flutter?
Flutter has certain limitations as:
4. Who developed the flutter framework?
Flutter Framework is developed by Google.
5. What are the resources to learn Flutter?
You can refer Flutter Documentation to learn flutter.
6. What type of applications can you develop using Flutter?
Flutter is an open-source UI toolkit by Google to develop android, iOS, Linux, Mac and Web applications from a single codebase. Flutter is a good choice for apps which needs to deliver high brand designs.
7. Explain the flutter widgets.
Flutter Widgets can be defined as an immutable description of a part of the UI. Each element on the flutter app's screen is considered as a widget. In flutter, the UI is built using widgets. There is no mutable state associated with a widget, you can use flutter stateful widget to associate a mutable state with a widget. For more about a widget class refer Widget class.
8. Is Flutter Open source?
Yes, Flutter is a free and open-source UI toolkit by Google to develop desktop, web and mobile applications with one codebase only.
9. What makes Flutter unique?
Flutter uses only a single codebase to develop applications for web, mobile and desktop and the experience for mobile apps is native on both android and iOS. Flutter does not depend on web browser technology nor the set of widgets that each device contains. Instead it uses its own rendering engine to draw widgets. This rendering engine provides very high performance. This concept makes flutter unique.
10. Explain Flutter SDK.
Flutter SDK is an UI kit to build applications for mobile, web and desktop from a single codebase. This SDK comes with a flutter command line tool and dart command line tool to develop apps across platforms. For more you can refer Flutter SDK.
11. What do you understand from hot reload and hot restart?
Hot reload means injecting the updated source code files into running Dart VM (Virtual Machine). Hot reload process does not add
only new classes but it also adds properties, fields and methods to existing classes, and changes existing functions.
Hot restart works by resetting the app's current state to the app's initial state.
For more you can visit Hot reload.
12. How does Flutter run the code on Android?
Android's NDK compiles the flutter engine's C,C++ code. The AOT (ahead-of-time) compiler compiles the Dart
code of both (SDK's and your) into native, ARM, and x86 libraries. These libraries are added in a "runner" android project and the whole thing or artefact is
built into an Android application package file .apk. The app loads the flutter library on launching of it. Any input or event handling, rendering and so on, are delegated
to the compiled code of flutter and app. It is similar to working process of many game engines.
During debug mode, A VM (Virtual Machine) runs flutter code in order to enable hot stateful reload feature. When you run app in debug mode you will see a "debug" banner
in top right corner of app. It reminds you that performance is not the characteristic of completed release app.
13. How does Flutter run the code on iOS?
The Flutter Engine's C, C++ code is compiled with LLVM (low level virtual machine - a compiling technology). The Dart code of both the SDK's and yours are
compiled by AOT (ahead-of-time) into a native, ARM library. That ARM library is included in "runner" iOS project and the whole code base is built into an
iOS App Store Package file .ipa. When the app launched, the app loads the flutter library. Any input or event handling, rendering and so on, are delegated
to the compiled code of flutter and app. It is similar to working process of many game engines.
Debug mode works same as for Android app.
14. In What technology is Flutter built?
Flutter is built using C, C++, Skia - 2D rendering engine and Dart (a modern, concise, object-oriented language). For you can visit Flutter System Architecture and Flutter architectural overview.
15. What is the use of the pubspec.yaml file?
When you create a new Flutter project, It includes a pubspec.yaml file also known as 'pubspec' at the top of the project tree. IT contains metadata
about the project that is required by Dart and Flutter tooling. It is written in YAML and human readable.
The pubspec file contains the dependency information that project requires like packages and their versions, fonts etc. It ensures that you get the same package version
the next time when you build the project. For more visit pubspec.
16. Explain stateful widgets and stateless widgets in flutter?
Radio, Checkbox, slider are examples of
stateful widgets.
IconButton, Icon, Text etc.17. What do you understand from 'State'? What is the use of the setState() method?
State refers to the information that you can read synchronously when a widget is built and it might change during the lifetime of the widget.
The widget implementor should ensure that the 'State' is promptly notified on change of state using State.setState method. The 'setState' method
is used to notify the changed state of an internal object.
18. Explain the lifecycle of a StatefulWidget?
19. What operating systems flutter support to build the apps?
Flutter app development can be done using Linux, MacOS, ChromeOS and Windows.
20. What is a Cookbook?
The Cookbook provides solutions or recipes for common occurring problems while developing flutter apps. Each recipe is an independent complete solution and can be referenced to help you build up an app. For more you can refer Cookbook.
21. What is the Container class in flutter?
The Container class provides the ability to create a widget with certain properties like padding, borders, height, width, border etc.
22. How will you make a HTTP request in flutter?
23. Can a container have more than one child?
24. What is SafeArea in flutter?
25. How JSON Serialization works in flutter?
26. How to Parse JSON in flutter?
27. What resources are available to learn flutter?
For Flutter tutorials visit Flutter Tutorials
27. What do you know about Dart?
28. What is the use of this keyword while creating constructors in Dart?
29. What are the extension methods in Dart? Why to use it?
30. In how many ways you can pass the parameters in Dart?
31. Explain different null operators in Dart.
32. How to access property or method conditionally in Dart?
33. Explain Spread operator.
34. What is Factory constructor in Dart? How will you create a factory?
35. How to check for types in Dart? Or What is sound typing in Dart?
36. What is the Asynchronous programming?
37. What is a future?
38. Explain async/await in Dart/Flutter.
39. Explain custom properties or getter and setter.
40. What are the methods to Parse JSON?
41. How to work with streams in Dart?
Where can you find answer of these questions?
For Dart Interview questions, we have a separate document here Dart Interview Questions
1. How much will you rate yourself in Flutter?
When you attend an interview, Interviewer may ask you to rate yourself in a specific Technology like Flutter, So It's depend on your knowledge and work experience in Flutter.
2. What challenges did you face while working on Flutter?
This question may be specific to your technology and completely depends on your past work experience. So you need to just explain the challenges you faced related to Flutter in your Project.
3. What was your role in the last Project related to Flutter?
It's based on your role and responsibilities assigned to you and what functionality you implemented using Flutter in your project. This question is generally asked in every interview.
4. How much experience do you have in Flutter?
Here you can tell about your overall work experience on Flutter.
5. Have you done any Flutter Certification or Training?
It depends on the candidate whether you have done any Flutter training or certification. Certifications or training are not essential but good to have.
We have covered some frequently asked Flutter Interview Questions and Answers to help you for your Interview. All these Essential Flutter Interview Questions are targeted for mid level of experienced Professionals and freshers.
While attending any Flutter Interview if you face any difficulty to answer any question please write to us at info@qfles.com. Our IT Expert team will find the best answer and will update on the portal. In case we find any new Flutter questions, we will update the same here.