CodeSubmit Interview Series

The 6 Best Flutter Interview Questions in 2023

What are the top Flutter interview questions? Here, you get some of the best Flutter interview questions to help you select your next Flutter developer. Read on!

Interviewing Flutter developers 

Flutter is an open-source UI software development kit. It was developed by Google in 2017 and today, it’s used to develop cross-platform applications for Android, iOS, Linux, Windows, Google Fuchsia, macOS, and the web from a single codebase. 

But how do you identify top Flutter developers? 

Here are the best interview questions to ask. 

Beginner Flutter interview questions

Below are some of our favorite Flutter interview questions to ask junior developers. Want to learn more? Read on. 

1. List the top benefits of Flutter. 


The main benefits of Flutter are: 

  • Cross-platform development: You can use Flutter to write, manage, and run code on multiple platforms. This saves energy, time, and money, plus standardizes your apps across different platforms. 

  • Reduce the amount of code: Flutter’s hot reload feature supports faster performance by compiling the application in the C/C++ library. You also have access to different widgets, which makes customization easy. 

  • Reduced risk for errors: Flutter is as close to machine code as possible, which reduces errors because of interpretation of code. 

  • Faster documentation: Flutter has fast and informative documentation that works as a central repository that stores documents for future reference. 

  • Customizable design: Flutter’s flexible UI makes it possible to customize designs. Flutter offers expressive UIs and fast rendering. 

  • Community support: Flutter has an active community that offers support. 

  • Minimal code: Flutter applications are built with the Dart programming language with JIT and AOT compilation for faster startup time and performance, as well as better functionality. 

2. Describe the Flutter architecture. 


Flutter consists of three layers. These are: 

1) Upper layers: Dart-based platform that includes app widgets, animations, illustrations, materials, and gestures. 

2) Flutter engine: Displays and formats text. 

3) Built-in service: Manages plugins, even loops, and packages. 

3. What skills are required to use Flutter? 


These are the main skills you should know to use Flutter successfully: 

  1. Dart programming language: Flutter uses the Dart programming language, so you should have a good understanding of Dart to write code for Flutter applications.

  2. Flutter framework: You should have a strong understanding of the Flutter framework and its components, including widgets, routes, and navigation.

  3. UI/UX design: Flutter provides a range of widgets for building custom user interfaces, but you need a good understanding of UI/UX design principles to create visually appealing and user-friendly interfaces.

  4. Mobile app development: You need to have experience with mobile app development, including knowledge of native mobile app development concepts, such as asynchronous programming, debugging, and publishing applications to app stores.

  5. Third-party libraries: You need to be familiar with third-party libraries and packages available in the Flutter ecosystem, such as Firebase, which can help in adding features like push notifications, authentication, and real-time databases.

4. What are the limitations of Flutter?


The limitations of Flutter include: 

Size of the application: The size of the Flutter application can be larger than native mobile applications, especially for simple apps, as Flutter includes its own set of libraries and widgets.

Limited access to native APIs: Although Flutter provides plugins to access native APIs, the number of plugins available for accessing native functionality is limited. This can make it challenging to integrate third-party libraries that require access to native APIs.

Limited support for older devices: Flutter has limited support for older mobile devices with lower processing power, limited memory, and slower internet connections. This can result in performance issues and slow app loading times.

Debugging: Debugging can be challenging in Flutter as the framework uses a reactive programming model, which can make it difficult to track errors and bugs.

Learning curve: Although Flutter is easy to learn for developers who are familiar with mobile app development, it can be challenging for developers who are new to mobile app development and unfamiliar with reactive programming concepts.

Advanced Flutter interview questions

What are the top Flutter interview questions for senior developers? Let’s find out. 

5. Can you explain the difference between runApp() and main() functions in Flutter?


In Flutter, main() is the entry point of the application, which is executed when the application starts. It's a standard Dart function that takes an array of strings as an argument and returns void. The main() function typically includes the code to start the application by calling runApp().

On the other hand, runApp() is a method from the Flutter framework that takes a widget as an argument and starts the Flutter application. The widget that is passed to runApp() serves as the root of the widget tree for the application. 

6. Explain the different types of streams in Flutter.


Streams in Flutter are a mechanism for handling asynchronous data, such as user input, network requests, or changes to data models. There are two types of streams in Flutter:

Single-subscription streams: These are streams that can only have a single listener at a time. Once a listener is registered, the stream will start emitting data, and the listener will receive all future events from the stream. Examples of single-subscription streams in Flutter include Future and StreamController.

Broadcast streams: These are streams that can have multiple listeners at the same time. Once a listener is registered, the stream will start emitting data, and all listeners will receive the same events from the stream. Examples of broadcast streams in Flutter include Stream and ValueNotifier.

Single-subscription streams are typically used for long-running asynchronous operations that are expected to complete only once, such as network requests or file operations. Broadcast streams are typically used for events that can occur multiple times and can be of interest to multiple parts of an application, such as user input or changes to data models.

Over to you!

There you have it! Now you know what some of the top Flutter interview questions are. 

But interviews are one part of the hiring process. You also need to assess your candidates.

That’s what CodeSubmit helps you do. 

CodeSubmit offers coding assessment tests that make it easy to recruit your next developer. 

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