Are you looking for Flutter interview question for a 1 year experienced developer? Here are 50 commonly asked interview questions about the popular open-source UI framework – Flutter. Covering topics such as Dart language fundamentals, state management strategies, best practices, and more.
What is Flutter and how does it differ from other mobile development frameworks?
What are Flutter widgets and how do they differ from traditional mobile app elements?
What is the Dart programming language and how is it used in Flutter development?
Outline the lifecycle of
Creation: When a
StatefulWidget is created, the framework calls the
createState() method of the widget, which returns an instance of a separate State object. The
createState() method is responsible for initializing the widget’s state.
Initialization: The framework then calls the
initState() method of the State object, which is responsible for initializing any resources that the widget requires. This is the first time the
build() method is called.
Building: The framework calls the
build() method of the State object to create the widget’s visual representation. Every time the widget needs to be redrawn on the screen, this method is called.
Updating: When the widget’s state changes, the framework calls the
setState() method, which schedules a rebuild of the widget. When the rebuild is triggered, the
build() method is called again, passing in the new state.
Destruction: When a widget is removed from the widget tree, the framework calls the
dispose() method of the State object. This method is responsible for cleaning up any resources the widget used before it was destroyed.
It’s important to note that the setState() method can be called multiple times during the lifecycle of a StatefulWidget, but the initState() and dispose() methods are called only once each.
Can you explain the concept of “hot reload” in Flutter and its benefits?
Give me 4 advantages of using Flutter?
Give me some limitations of Flutter?
When would you use profile mode in Flutter?
What is Container class in Flutter?
Containerclass in Flutter is a convenience widget that allows developers to easily create a box with some padding and a specified width, height, and color. It is often used as a parent widget to hold and position other widgets.
What is a SizedBox in flutter?
SizedBoxwidget is a simple container that can specify a fixed width and/or height. It is a convenience widget that can be used to add empty space between widgets or force a widget to have a specific size.
Explain how a SizedBox is different from a Container?
In Flutter, both SizedBox and Container widgets are used to hold and position other widgets, but they have different purposes and behaviors.
A Container widget is a general-purpose container that can be used to hold and position other widgets, set the size and color of the container, and apply padding and margins. It can also be used to apply a specific width and height. It also allows setting decorations such as background images, gradients, etc.
A SizedBox widget, on the other hand, is a simple container used to specify a fixed width and/or height. It does not take any space in the layout itself. It just influences the size of its child. It’s commonly used to add empty space between widgets or force a widget to have a specific size.
How does the layout and rendering process work in Flutter?
How does Flutter handle the issue of different screen sizes and resolutions on different devices?
When should you use keys in Flutter?
mainAxisAlignmentproperty of a
Columnwidget is used to align the child widgets along the container’s main axis. The main axis of a
Rowis horizontal, and the main axis of a
crossAxisAlignmentproperty of a
Columnwidget is used to align the child widgets along the container’s cross-axis. The cross-axis of a
Rowis vertical, and the cross-axis of a
Explain why Futures are used in Dart?
Futureis an asynchronous operation that can complete in the future with a value or an error. It represents a single computation or action that is not completed immediately but is expected to be completed at some point in the future.
What are some best practices for designing and developing apps using Flutter?
Explain what pubspec.yaml files are for?
pubspec.yaml files are used in Flutter projects to manage dependencies. It is a configuration file containing the package’s metadata, including the package name, version, and dependencies.
The file lists the package’s dependencies, including both the Dart packages and the assets that the package needs to run, such as images and fonts.
When you run the
flutter packages get command, it reads the
pubspec.yaml file and downloads the dependencies specified in the file, making them available to your app.
This file also allows you to specify the minimum version of the flutter sdk that your package supports and specify assets, fonts and other configurations.
Additionally, developers can also use this file to specify the version of the package, the author, and other useful information when publishing a package on the Dart Package Repository.
Explain how runApp() is different from main()?
main() are separate but related functions.
main() is the app’s entry point and is where the Dart runtime starts executing the app’s code. It is the standard
main() function in any Dart program.
runApp() is a Flutter-specific function used to start the Flutter app and attach it to the screen. It takes a widget as an argument and uses it as the root widget of the app.
main() function is responsible for defining and initializing the app, setting up the dependencies and, calling the
runApp() function, passing the root widget of the app as an argument.
What is the use of
Streamis a way to handle asynchronous data that can be produced over time, such as user input, network responses, or sensor data. A
Streamis a sequence of asynchronous events, and a value or an error represents each event.
How does Flutter handle app localization and internationalization?
How does Flutter handle navigation and routing in the app?
How would you make sure you’re using all features of Flutter?
How does Flutter handle HTTP requests and networking?
httppackage for making HTTP requests and handling responses. You can use the package to make
DELETErequests, and handle responses with
XML. You can also use external libraries such as
chopperfor networking, they provide more advanced features like caching, request cancelation, retry and more.
Explain what the setState() method does?
setState() method is a built-in method in Flutter that allows you to update the state of a
When a user interacts with a
StatefulWidget (e.g. by tapping a button), the widget’s state may need to change. For example, a button’s text may change from “Like” to “Unlike” when pressed.
setState() method is used to indicate that the widget’s state has changed and that the widget should be “rebuilt” or “redrawn” on the screen with the updated state. The
setState() method takes one argument, a callback function specifying the changes to be made to the widget’s state.
How does Flutter handle storage and database management?
sqflitepackage for storing data locally on the device. It provides a way to store and retrieve data in a SQLite database. Additionally, there are other popular packages such as
shared_preferencesthat provide more advanced features for storing and managing data.
Can you explain the concept of streams in Flutter and how they are used?
Streamsin Flutter are used to handle asynchronous data, such as user input or network responses. A stream is a sequence of asynchronous events. It can be used to listen to data and react to it as it arrives. In Flutter, streams are implemented using the
dart:asynclibrary and can be used with the
StreamBuilderwidget to automatically rebuild the UI when new data arrives.
How can we test our Flutter app?
testpackage to create unit tests for your app’s business logic.
flutter_testpackage to create widget tests for your app’s UI.
flutter_driverpackage to run integration tests that interact with your app as a user would.
How can we deploy our Flutter app to different app stores?
flutter buildto build the app for different platforms. You can use it to build the app for iOS and Android. Once the app is built, you can then upload it to the App Store or Google Play Store for distribution.
flutter_webmodule, which allows you to run Flutter apps in the browser using the same codebase as your mobile app. This means that you can use the same widgets, layout, and logic for both web and mobile apps, making it easier to develop and maintain cross-platform apps.
firebase_messagingpackage. It provides an easy-to-use API that allows you to receive and handle push notifications in your app. You can also use other popular packages such as
flutter_local_notificationsfor push notifications.
in_app_purchasepackage. It provides an easy-to-use API that allows you to handle in-app purchases on both iOS and Android. You can also use other popular packages such as
billing_clientfor in-app purchases.
Semanticswidget to provide additional information about the interface to assistive technologies, such as screen readers. Also, you can use the
Focuswidget to handle keyboard navigation and accessibility in forms.
flutter_analyticsto track user behavior and app usage. You can also use other popular analytics services like Google Analytics or Mixpanel. These packages provide easy-to-use APIs that allow you to track events and user behavior in your app.
SplashScreenpackage. It provides a simple way to show a splash screen while your app is loading. You can customize the splash screen by providing a background color, logo, and text. Alternatively, you can create your own splash screen by using the
Stackwidget and placing an
Imagewidget as the background, and then using a
FutureBuilderwidget to wait for the app to be initialized before navigating to the next screen.
image_pickerpackage to pick an image from the gallery or camera and the
image_cropperpackage to crop the selected image. Both packages provide an easy-to-use API that allows you to pick and crop images in your app.
firebase_messagingpackage. It provides an easy-to-use API for using FCM to send and receive push notifications. You can use it to register the app with FCM, subscribe to topics, and handle incoming push notifications.
locationpackage. It provides an easy-to-use API for getting the device’s current location and tracking location changes in the background. You can use it to get the device’s current location and then track the location changes in the background, even when the app is closed.
How can we implement a Drawer in Flutter?
Drawerwidget. It provides a simple way to show a side menu containing navigation links or other options. You can customize the drawer by providing a background color, logo, and text. You can also use the
DrawerItemwidgets to create a more structured and customized drawer.
How can we implement a Bottom Navigation Bar in Flutter?
BottomNavigationBarwidget. It provides a simple way to show a navigation bar at the bottom of the screen containing navigation links or other options. You can customize the bottom navigation bar by providing different icons and labels for each option. Additionally, you can also use the
BottomNavigationBarItemwidget to create a more structured and customized bottom navigation bar.
How can we implement a TabBar in Flutter?
TabBarwidget. It provides a simple way to show a tab bar at the top of the screen containing navigation links or other options. You can customize the tab bar by providing different icons and labels for each option. Additionally, you can also use the
Tabwidget to create a more structured and customized tab bar.
How can we implement a Carousel in Flutter?
carousel_sliderpackage. It provides an easy-to-use API for creating a carousel of images or other widgets. You can use it to show a series of images or other widgets in a scrolling view, and customize the carousel by providing different options such as the animation duration, autoplay, and more.
How can we implement a Map in Flutter?
google_maps_flutterpackage. It provides an easy-to-use API for showing Google Maps in your app. You can use it to show a map view, add markers, change the camera position, and customize the appearance of the map. Additionally, you can also use other packages like
mapbox_glto implement a map feature in your app.
What are unit tests?
Unit tests are a way to test individual units of code, such as individual functions or classes, to ensure that they behave as expected. In Flutter, unit tests are used to test the logic and behaviour of the app’s code and to verify that the app behaves correctly in different scenarios.
Flutter provides a built-in testing framework that makes writing and running unit tests for your app easy. The framework is based on the Dart
test package, allowing you to test your app’s widgets, state, and logic in a simulated environment.
To write a unit test in Flutter, you create a separate
.dart file in the test folder and use the
test() function to define the test. The
test() function takes two arguments: a string describing the test and a callback function that contains the test logic.
How can we implement a Video Player in Flutter?
video_playerpackage. It provides an easy-to-use API for playing videos in your app. You can use it to play videos from different sources such as a network or a file, customize the playback controls, and handle video events such as completion or error.
How can we implement a Firebase Authentication in Flutter?
firebase_authpackage. It provides an easy-to-use API for using Firebase Authentication in your app. You can use it to authenticate users using different methods such as email and password, phone number, and more. Additionally, you can also use other packages like
flutter_facebook_loginto implement Firebase Authentication feature in your app.
How can we implement a Firebase Cloud Storage in Flutter?
firebase_storagepackage. It provides an easy-to-use API for using Firebase Cloud Storage in your app. You can use it to upload and download files, handle progress, and manage files in the storage.
How can we implement a Firebase Cloud Firestore in Flutter?
cloud_firestorepackage. It provides an easy-to-use API for using Firebase Cloud Firestore in your app. You can use it to read and write data to the Firestore, handle events such as changes in the data, perform complex queries and operations, and manage collections and documents in the Firestore.