Are you preparing for the Flutter Interview? In this section, you will learn a variety of Flutter Interview questions and answers ranging from fundamental to more advanced topics. Build your small projects to solidify your understanding, showcase your Flutter skills and problem-solving.
Flutter is an open-source framework built on top of Dart programming language. Flutter is developed by Google and is used for building web applications, mobile applications for iOS and Android, and desktop applications.
Let’s go through some Flutter technical interview questions and answers to build more knowledge and ace your next Flutter job interview.
The following reasons make Flutter a favorite among developers for many app development projects:
It is easy to learn making it suitable for experienced and beginner developers
It facilitates cross-platform app development
Low development cost
Short time-to-market with write-once-deploy-everywhere capability, along with fast development cycles
Native performance achieved by Dart programming language and custom rendering engine
One codebase for all platforms which can be used for Android, iOS, desktop, and web applications
Rich libraries with Skia Graphics Library
It’s all widgets principle
Fast testing with hot reload
The widget tree is the hierarchical structure and organization of the widget that makes up the app UI. Widgets are the basic building blocks of the app UI in Flutter. In a widget tree, each node is a widget.
The Flutter Inspector is a powerful tool that helps developers visualize, inspect, and understand the widget trees of their apps.
The Flutter inspector helps identify layout issues and helps in making dynamic changes via hot reload.
Packages in Flutter are reusable libraries of Dart code that can be added to the code to provide specific functionality to the app. The packages are hosted on the pub.dev website and can be included in the projects by specifying them in the pubspec.yaml file of the project.
Plugins are a subset of packages that contain platform-specific code. They contain both Dart code and platform-specific code, which may be Java/Kotlin for Android or Swift/Objective - C for iOS.
The Flutter architecture consists of the following layers
Embedder Layer
Engine Layer
Framework Layer
Embedder layer - the embedder layer consists of platform-specific code that allows Flutter to interact with the underlying operating system.
The Engine layer - This consists of the core of the framework which is written in C/C++. It is responsible for low-level rendering using the Skia Graphics Library. The engine layer is also responsible for service and network protocols.
The following are the components of the Engine Layer:
Rendering - handles the rasterization
Text Layout - Manages text layout and rendering
Dart Runtime - Executes Dart code
Service and Network Protocols - Manages communications for service and networking
The Framework layer - this is the layer where a developer writes the Flutter applications. It consists of three main layer components.
The foundation layer - this layer is the collection of basic classes and building block services that provide abstractions to Flutter.
Rendering layer - This layer converts the widget tree into a renderable format
Widget layer - the widget layer is a composition abstraction
Build modes in Flutter are the different ways to compile the source code for an app.
There are three different build modes:
Debug mode
Profile mode
Release mode
Debug mode: This mode is used for debugging, rapid iteration, and testing during development
Profile mode: this mode is designed to test your app’s performance during development
Release mode: This mode is designed to deploy the app to the users.
The Navigator and Router in Fluetter are used for navigating between screens and handling deep links.
Applications without complex deep linking can use Navigator. Navigator is used to navigate between screens in an app.
Routers are used for handling complex routing scenarios including deep linking and advanced routing.
Hot reload helps the developers to see the results of the changes in their code immediately without restarting the app.
Hot restart completely restarts an app, loads the entire Dart code from scratch, and recompiles the entire codebase.
One of the major differences between the two is that while hot reload preserves the app’s state, hot restart doesn’t.
The event loop is a fundamental concept in Flutter’s asynchronous programming model. It manages the execution of code events and callbacks by processing one event at a time. The event loop works by checking two key queues: the event queue and the microtask queue.
The event queue contains events such as mouse clicks, tap gestures, and other external interactions. In contrast, the microtask queue is used for short asynchronous tasks that need to be executed as soon as possible, such as completing internal operations or handling promises. By efficiently managing these queues, the event loop ensures smooth and responsive app behaviour.
Tree shaking in Flutter is an optimization technique to reduce the size of the application. It is a process that helps in removing unused or redundant code from your app.
Tree shaking helps ensure that only necessary code is included in the final build which, in turn, results in faster load times, reduced memory usage, improved performance, and adherence to app store guidelines.