100+ Flutter Developer Interview Questions and Answers

Yes, Firebase Firestore is a flexible, scalable database for mobile, web, and server development.

• Firebase Firestore is a NoSQL document database that stores data in collections and documents.

• It allows for real-time data synchronization and offline support for web and mobile applications.

• Firestore offers powerful querying capabilities and integrates seamlessly with other Firebase services.

• Example: Firestore can be used to store user profiles, chat messages, and application set...read more

Hive is a lightweight and fast key-value database for Flutter and Dart.

• Hive is a NoSQL database that stores data in key-value pairs.

• It is designed to be fast, efficient, and easy to use in Flutter applications.

• Hive uses type adapters to serialize and deserialize custom objects for storage.

• Example: Storing user settings or cached data in a Flutter app.

Signing in Android refers to the process of digitally signing an Android application package file (APK) to ensure its authenticity and integrity.

• Signing involves using a private key to generate a digital signature for the APK file.

• The digital signature is verified by Android devices to confirm that the app has not been tampered with.

• Signing is important for app distribution through Google Play Store and for security purposes.

• Examples of signing tools include jarsigner and And...read more

I ensure app responsiveness by optimizing code, using efficient layouts, and testing on various devices.

• Optimize code by reducing unnecessary computations and using efficient algorithms

• Use responsive layouts like Flexbox and MediaQuery to adapt to different screen sizes

• Test app performance on various devices to ensure smooth user experience

I primarily use the BLoC (Business Logic Component) architecture in Flutter.

• BLoC architecture separates the business logic from the UI, making the code more organized and easier to maintain.

• It involves creating streams of data to manage the state of the application.

• BLoC pattern is widely used in Flutter for its scalability and testability.

• Other popular architectures in Flutter include Provider, Redux, and MVC.

Create a card similar to Leetcode profile

• Use Flutter to create a card layout

• Include profile picture, username, rating, and badges

• Add a section for solved problems and submission history

Create a git repository for the project

• Initialize a new git repository in the project directory using 'git init'

• Add all project files to the staging area using 'git add .'

• Commit the changes with a descriptive message using 'git commit -m 'Initial commit''

• Create a new repository on a git hosting service like GitHub or GitLab

• Link the local repository to the remote repository using 'git remote add origin '

• Push the code to the remote repository using 'git push origin master'

Implementing Google sign up on a screen

• Integrate Google sign-in SDK into the app

• Add a Google sign-in button on the screen

• Handle authentication flow and user data retrieval

• Implement error handling for sign-up process

To fetch and store data from server, use HTTP requests to retrieve data and local storage to save it.

• Use HTTP requests like GET, POST, PUT, DELETE to fetch data from server

• Parse the response data and store it locally using shared preferences, SQLite, or other local storage options

• Implement error handling and data caching for better user experience

Flutter apps are built using Dart programming language and Flutter framework.

• Flutter uses a reactive programming model.

• Widgets are the building blocks of a Flutter app.

• Flutter has a rich set of pre-built widgets and tools.

• Flutter apps can be compiled to run on multiple platforms.

• Flutter uses a hot reload feature for faster development.

• Flutter apps can be built using Android Studio, Visual Studio Code, or IntelliJ IDEA.

Dependency Inversion principle states that high-level modules should not depend on low-level modules. Both should depend on abstractions.

• High-level modules should not depend on low-level modules. Both should depend on abstractions.

• Abstractions should not depend on details. Details should depend on abstractions.

• This principle helps in achieving decoupling and flexibility in the codebase.

• Example: Instead of directly calling a specific database implementation in a high-level mod...read more

Flutter is a mobile app SDK for building high-performance, high-fidelity, apps for iOS and Android, using a single codebase.

• Flutter is developed by Google.

• It uses Dart programming language.

• Flutter's engine name is Skia.

• Flutter allows for hot reload, which speeds up the development process.

• Flutter has a rich set of pre-built widgets for building beautiful UIs.

• Flutter is used by popular apps like Alibaba, Google Ads, and Reflectly.

To add voice over (accessibility) support to a Flutter app, use the accessibility features provided by Flutter and customize them as needed.

• Use Semantics widget to add accessibility labels and actions to widgets in the app

• Customize the voice over experience by providing specific instructions and descriptions for each widget

• Test the accessibility features using a screen reader to ensure they work as intended

State management tools in Flutter help manage the state of widgets and data in an efficient way.

• Provider: A simple way to manage state in Flutter applications.

• Bloc: A predictable state management library that helps manage the state of widgets.

• GetX: A lightweight and fast state management solution for Flutter applications.

• Riverpod: A provider package that helps manage state and dependencies in Flutter.

• Redux: A predictable state container for Flutter applications.

const and final are both used to declare variables that cannot be reassigned, but const is evaluated at compile-time while final is evaluated at runtime.

• const variables are implicitly final but final variables are not implicitly const

• const variables must be initialized with a constant value, while final variables can be initialized with a non-constant value

• const variables are evaluated at compile-time while final variables are evaluated at runtime

• const variables are implicitl...read more

Yes, Web sockets in Flutter allow for real-time communication between a client and server.

• Web sockets in Flutter enable bidirectional communication between client and server

• They are useful for real-time applications like chat apps, live updates, and multiplayer games

• Flutter provides a WebSocket class for implementing web sockets in apps

Stateless widgets are immutable and don't change over time. Stateful widgets can change their state over time.

• Stateless widgets are used for displaying static content.

• Stateful widgets are used for displaying dynamic content.

• Stateless widgets are faster and consume less memory than stateful widgets.

• Stateful widgets have a State object that stores mutable state.

• Examples of stateless widgets include Text, Icon, and Image.

• Examples of stateful widgets include Checkbox, Radio, and ...read more

To parse JSON API, use a JSON parser library or built-in functions in programming languages.

• Use a JSON parser library like Gson, Jackson, or Moshi in Java

• Use built-in functions like json.loads() in Python

• Parse JSON data into objects or dictionaries for easy access

• Handle errors and exceptions when parsing JSON data

Program to check if a number is prime

• Iterate from 2 to square root of the number and check for divisibility

• If the number is divisible by any number other than 1 and itself, it is not prime

• Return true if the number is prime, false otherwise

Java is a high-level programming language used for developing applications and software.

• Java is an object-oriented language

• It is platform-independent

• It is used for developing web, mobile, and desktop applications

• Java is used in Android app development

• Java is used for creating server-side applications

• Java is used for developing enterprise-level applications

I started my developer journey by learning programming languages and building small projects.

• Started with learning basic programming concepts

• Learned multiple programming languages such as Java, Python, and JavaScript

• Built small projects to practice and improve skills

• Explored different frameworks and technologies to specialize in

• Continuously learning and improving skills

Create input fields to capture data and display it in the console using Flutter.

• Create a TextFormField widget to capture user input.

• Use a RaisedButton widget to submit the data entered in the TextFormField.

• Print the entered data in the console using print() function.

Flutter is an open-source UI software development kit created by Google for building natively compiled applications for mobile, web, and desktop from a single codebase.

• Flutter is a framework for building high-performance, high-fidelity apps for iOS, Android, web, and desktop

• It uses Dart programming language

• Flutter provides a rich set of pre-built and customizable widgets

• Flutter's hot reload feature allows for faster development and debugging

• Flutter is used by companies like A...read more

I approach optimization by analyzing performance metrics, identifying bottlenecks, and implementing efficient solutions.

• Analyze performance metrics to identify areas for improvement

• Optimize code by reducing unnecessary computations and improving algorithms

• Utilize tools like Flutter DevTools to profile and debug performance issues

Yes, I have experience in developing apps single handedly.

• I have developed several apps single handedly in the past.

• I am proficient in using various tools and technologies required for app development.

• I am capable of handling all aspects of app development including design, development, testing, and deployment.

• I am a self-motivated and disciplined individual who can work independently.

• I am also comfortable working in a team environment if required.

The app 2 used packages like provider, http, shared_preferences, etc.

• provider

• http

• shared_preferences

A widget tree is a hierarchy of widgets in Flutter that represents the UI components of an application. Build context is an object that provides information about the location of a widget within the widget tree.

• Widget tree is a collection of nested widgets that define the structure of the user interface.

• Build context is an object that holds information about the location of a widget in the widget tree.

• Widgets use the build context to access properties of their parent widgets ...read more

State management in Flutter is crucial for managing the state of widgets and data throughout the app.

• Flutter provides various options for state management such as setState, InheritedWidget, Provider, Bloc, Redux, MobX, etc.

• Provider is a popular state management library in Flutter that allows for efficient and scalable state management.

• Bloc is another commonly used library that helps in managing the state of the app by separating the business logic from the UI.

• Redux and MobX a...read more

Flutter uses a single thread for the main UI and multiple threads for background tasks.

• Flutter uses a single thread for the main UI event loop.

• Additional threads are used for background tasks such as network requests and file I/O.

• The number of threads used by Flutter can vary depending on the device and platform.

• Flutter's asynchronous programming model allows for efficient use of threads.

• Developers can also create their own isolates for parallel processing.

Yes, I have built an SDK for a Flutter project.

• I have experience building custom SDKs for Flutter projects to provide specific functionalities or integrations.

• I have created SDKs for handling API calls, data storage, authentication, and other common tasks.

• One example is a custom SDK I built for integrating a payment gateway into a Flutter app.

Yes, I have used Firebase for real-time database, authentication, and cloud messaging in Flutter projects.

• Utilized Firebase real-time database for storing and syncing data in real-time

• Implemented Firebase authentication for user sign-in and sign-up processes

• Integrated Firebase cloud messaging for push notifications

Widgets in Flutter are the building blocks of the user interface, ranging from simple components like buttons to complex layouts.

• Widgets are classes used to construct the user interface in Flutter.

• There are two types of widgets: StatelessWidgets, which are immutable, and StatefulWidgets, which can change over time.

• Widgets can be combined to create complex UI elements, such as rows, columns, grids, and more.

• Examples of widgets include Text, Image, Container, ListView, AppBar, ...read more

A callback URL is a URL provided by the developer to receive notifications or data from an external service or API.

• It is used in web development to specify where a server should send data after completing a request.

• Callback URLs are commonly used in OAuth authentication flows to redirect users back to the application after authentication.

• They can also be used in webhooks to notify a server about events or updates.

Dependency injection is a design pattern used to remove hard-coded dependencies and make components more modular and testable.

• Dependency injection involves providing a dependent object with the objects it depends on, rather than creating them itself.

• There are three types of dependency injection: constructor injection, setter injection, and interface injection.

• Example: In Flutter, dependency injection can be achieved using packages like get_it or provider.

Flutter compute is a function that runs heavy computations in a separate isolate to avoid blocking the main UI thread.

• Flutter compute is used to offload heavy computations from the main UI thread to prevent UI lag.

• It runs the computation in a separate isolate, which is a separate memory space with its own event loop.

• The result of the computation is sent back to the main UI thread using Future or async/await.

• Example: compute function is commonly used for parsing large JSON dat...read more

Material Design is a design language developed by Google that combines principles of good design with innovation and technology.

• Developed by Google for Android apps and web applications

• Focuses on clean, minimalistic design with depth and motion

• Uses grid-based layouts, responsive animations, and transitions

• Encourages consistent use of color, typography, and iconography

Method channels are a way for Flutter code to communicate with platform-specific code in Android and iOS.

• Method channels allow Flutter code to call platform-specific code written in Java/Kotlin for Android or Objective-C/Swift for iOS.

• They enable bi-directional communication between Flutter and platform code.

• Method channels are used for tasks like accessing device sensors, making network requests, or interacting with platform-specific APIs.

Polymorphism is the ability of a function or method to behave differently based on the object it is acting upon.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• There are two types of polymorphism: compile-time (method overloading) and runtime (method overriding).

• Example: In Flutter, the build method in a Widget class can be overridden in subclasses to customize the UI.

State management is the process of managing and updating the state of an application to ensure data consistency and UI synchronization.

• State management involves handling the data that an application needs to keep track of, such as user input, network requests, and local data.

• It helps in updating the UI based on changes in the data, ensuring a seamless user experience.

• There are various state management solutions in Flutter, such as Provider, Bloc, Redux, and Riverpod.

• Example: ...read more

Find the 3rd largest integer in an array.

• Sort the array in descending order and return the 3rd element.

• Use a loop to find the 3rd largest element without sorting.

• Use a heap to find the 3rd largest element in O(n) time.

I primarily use Provider and Riverpod for state management in Flutter development.

• Provider is a simple, flexible, and scalable state management solution.

• Riverpod is a provider package that makes it easier to work with Provider and adds additional features.

• I also have experience with Bloc and MobX for state management in Flutter.

BLoC is a design pattern used in Flutter for managing state and handling events.

• BLoC stands for Business Logic Component.

• It separates the presentation layer from the business logic layer.

• It uses streams to handle events and state changes.

• It can be used with other design patterns like MVVM and Redux.

• Example: Counter app using BLoC pattern.

• Example: Login form using BLoC pattern.

Remove duplicates from a list of strings

• Create a Set to store unique elements

• Iterate through the list and add each element to the Set

• Convert the Set back to a list to get the unique elements

Probity helped me ensure ethical behavior and compliance with regulations.

• Probity helped me maintain transparency in all my actions.

• It ensured that I followed all legal and ethical guidelines in my work.

• Probity helped me build trust with clients and stakeholders.

• It also helped me avoid conflicts of interest and maintain integrity in my work.

Asynchronous programming is a programming paradigm that allows multiple tasks to be executed concurrently, improving performance and responsiveness.

• Allows tasks to run concurrently without blocking the main thread

• Improves performance and responsiveness by handling tasks in the background

• Uses callbacks, promises, or async/await keywords to manage asynchronous operations

Validations in Flutter are used to ensure that user input meets certain criteria before processing.

• Validations are used to check if user input is in the correct format or range.

• Common validations include checking for required fields, email format, password strength, etc.

• Flutter provides built-in validators like 'required' and 'email' for TextFormField widgets.

• Custom validators can be created using regular expressions or custom logic.

An array in Java is a fixed-size data structure that stores elements of the same data type. An ArrayList is a dynamic-size data structure that can grow or shrink as needed.

• Arrays in Java are fixed in size and can store elements of the same data type. They are accessed using an index starting from 0.

• ArrayList in Java is a dynamic array that can grow or shrink in size. It is part of the Java Collections Framework and provides more flexibility than arrays.

• Example: String[] names...read more