Beginner Android Interview Questions

ANDROID INTERVIEW QUESTIONS & ANSWERS

1. What is Android?

Android is an open-source mobile operating system developed by Google. It is primarily used for smartphones, but it also powers tablets, smart TVs, wearables, and even car infotainment systems.

Because Android is open-source, developers can build highly customizable applications and manufacturers can adapt it to different hardware.

2. What language is used for Android development?

Android officially supports multiple languages, but the most commonly used are:

🔸 Java – Traditional and widely used
🔸 Kotlin – Modern, concise, and preferred by Google

Today, Kotlin is recommended for new Android development because it reduces boilerplate code and improves safety.

3. What is an APK?

APK (Android Package Kit) is the installable file format for Android applications.
It contains compiled code, resources, assets, and manifest information required to run an app.

4. What are the main components of Android?

Android applications are built using four core components:

🔸 Activity
🔸 Service
🔸 Broadcast Receiver
🔸 Content Provider

Each component serves a specific purpose in the app lifecycle.

5. What is an Activity?

An Activity represents a single screen with a user interface.
For example, login screen, home screen, or settings screen are all activities.

6. What is Intent?

Intent is a message object used to communicate between Android components.
It tells the system what action to perform and where to perform it.

7. Types of Intent

🔸 Explicit Intent – Used within the same app
🔸 Implicit Intent – Used to interact with system features or other apps

Implicit intents are commonly used for actions like opening a browser or sharing content.

8. What is Fragment?

A Fragment is a reusable part of UI that lives inside an Activity.
It helps create flexible and modular UI designs.

9. Difference between Activity and Fragment

🔸 Activity – Independent component
🔸 Fragment – Dependent on Activity
🔸 Activity – Full screen
🔸 Fragment – Part of a screen

Fragments are commonly used in modern apps for better UI reuse.

10. What is AndroidManifest.xml?

It is a core configuration file that defines app details such as activities, permissions, services, and app entry points.

11. What is Context?

Context provides access to application resources, system services, and environment information.
It is essential for tasks like launching activities or accessing resources.

12. What is Toast?

Toast is a short popup message displayed to the user for brief feedback.

13. What is RecyclerView?

RecyclerView is used to display large lists efficiently by reusing views instead of creating new ones.

14. Difference between RecyclerView and ListView

🔸 RecyclerView is more flexible
🔸 Better performance
🔸 Highly customizable

RecyclerView is preferred in modern Android apps.

15. What is Layout?

Layout defines the UI structure of an Android app.

16. Types of Layouts

🔸 LinearLayout
🔸 RelativeLayout
🔸 ConstraintLayout
🔸 FrameLayout

17. What is ConstraintLayout?

A powerful layout that reduces nested views and improves UI performance.

18. What is SharedPreferences?

Used to store small key-value data such as user settings.

19. What is AVD?

AVD (Android Virtual Device) is an emulator used to test apps without a physical device.

20. What is Gradle?

Gradle is the build automation tool used to manage dependencies and build Android projects.

21. What is R.java?

It contains auto-generated resource IDs for layouts, strings, images, etc.

22. What is Logcat?

Logcat shows logs and debugging information, helping developers troubleshoot issues.

23. What is ANR?

ANR (Application Not Responding) occurs when the UI thread is blocked for too long.

24. What is ViewModel?

Stores UI-related data and survives configuration changes like screen rotation.

25. What is LiveData?

An observable data holder that is lifecycle-aware and updates UI safely.

26. What is Android Jetpack?

A set of libraries, tools, and best practices to simplify Android development.

27. What is Permission?

Permissions control access to sensitive features like camera, storage, or location.

28. What is Density-independent Pixel (dp)?

Ensures consistent UI size across different screen densities.

29. What is px?

Pixel (px) is a device-dependent unit, not recommended for layouts.

30. What is Kotlin?

Kotlin is a modern, safe, and concise language officially supported for Android.

31. Explain Android Architecture

🔸 Linux Kernel
🔸 Hardware Abstraction Layer (HAL)
🔸 Android Runtime (ART)
🔸 Native Libraries
🔸 Application Framework
🔸 Applications

32. What is ART?

Android Runtime executes DEX bytecode efficiently and improves performance.

33. Difference between DVM and ART

🔸 ART uses Ahead-of-Time (AOT) compilation
🔸 Improves app startup and runtime performance

34. What is MVVM?

MVVM stands for Model – View – ViewModel

🔸 Separates UI and business logic

35. What is Data Binding?

Allows UI components to bind directly to data sources.

36. What is Hilt?

Hilt is a dependency injection library built on Dagger.

37. What is Dependency Injection?

A design pattern where dependencies are provided externally.

38. What is WorkManager?

Handles reliable background tasks, even after app restarts.

39. What is Room Database?

Room is an ORM over SQLite that simplifies database access.

40. Serializable vs Parcelable

🔸 Parcelable is faster
🔸 Recommended for Android

41. What is ProGuard / R8?

Used for code shrinking, obfuscation, and optimization.

42. What is Retrofit?

A type-safe HTTP client for API communication.

43. What is OkHttp?

A low-level HTTP networking library.

44. What is Coroutine?

Handles asynchronous tasks without blocking UI thread.

45. Coroutine vs Thread

🔸 Coroutines are lightweight
🔸 Better performance and scalability

46. What is Flow?

Used for asynchronous data streams.

47. What is LifecycleOwner?

A component that follows Android lifecycle events.

48. What is Broadcast Receiver?

Listens for system-wide events like network or battery changes.

49. What is Foreground Service?

A service that runs with a visible notification.

50. What is Memory Leak?

Occurs when unused objects are not garbage collected.

51. How to detect memory leaks?

🔸 LeakCanary
🔸 Android Profiler

52. What is ViewBinding?

Generates binding classes to avoid findViewById().

53. ViewBinding vs DataBinding

🔸 DataBinding supports expressions
🔸 ViewBinding is lightweight and faster

54. What is Navigation Component?

Manages safe and structured in-app navigation.

55. What is Deep Linking?

Opens a specific app screen using a URL.

56. What is Push Notification?

Messages sent from server using Firebase Cloud Messaging (FCM).

57. What is Firebase?

Backend platform for authentication, database, analytics, and notifications.

58. What is Play Store App Signing?

Google securely manages app signing keys.

59. What is ASO?

App Store Optimization improves visibility and downloads.

60. How to improve Android app performance

🔸 Use ConstraintLayout
🔸 Avoid memory leaks
🔸 Optimize images
🔸 Use background threads
🔸 Apply lazy loading