Below is a list of questions I asked in an interview for a middle developer. The concept of "Middle Developer" differs from company to company and even from project to project, therefore these questions may seem very complex to you, or vice versa, very simple for this position.

Each question has links to articles that contain the answer to the question and could be given to the developer if he/she is not answered the related question.

If you don't agree with this list or have suggestions on what to change/add to it, we can always discuss in the Discussions.

If you have a list of questions for a middle android developer that you want to share, please create a pull request, it's always welcome.

General

1. What do you know about YAGNI, KISS, DRY?

• Yagni
• The KISS Principle in Software Development – Everything You Need to Know
• The DRY Principle: Reducing Redundancy for Clean Code

Kotlin

2. What is the difference between abstract class and interface?

• Interfaces and Abstract Classes
• What is the difference between an interface and abstract class?

3. Describe nullability and null safety

• Nullability in Java and Kotlin
• Null safety

4. What scope functions do you know?

• Scope functions

5. What do you know about data classes?

• Data classes
• Data Class in Kotlin

6. What do you know about sealed classes and interfaces?

• Sealed classes and interfaces
• Unlocking the Power of Sealed Classes in Kotlin: Design Patterns and Better Code Organization
• Kotlin Sealed Class (Examples, Uses, How to Use)

7. What do you know about extensions?

• Extensions
• Extension Functions in Kotlin

8. What is the difference between lazy and lateinit?

• Property initialization using by lazy vs. lateinit
• Initializing lazy and lateinit variables in Kotlin

9. What do you know about the object keyword?

• Object expressions and declarations
• Understanding the Object Keyword in Kotlin
• Objects in Kotlin: Create safe singletons in one line of code

Android

10. What is Context?

• Mastering Android context
• Which Context should I use in Android?
• Fully understand Context in Android
• What is Context in Android and which one should you use?

11. Describe Activity lifecycle

• The activity lifecycle
• Android activity life cycle - what are all these methods for?

12. What launch modes do you know?

• Understand Android Activity's launchMode: standard, singleTop, singleTask and singleInstance
• Understand the types of Launch Modes in an Android Activity
• Android Activity Launch Mode

13. Describe Fragment lifecycle

• Fragment lifecycle
• Android Fragment Lifecycle

14. Describe View lifecycle

• The Life Cycle of a View in Android
• Android View Lifecycle
• Understanding View Lifecycle in Android

15. What do you know about DiffUtil?

• DiffUtil
• Using DiffUtil in Android RecyclerView

16. What is ViewModel?

• ViewModel overview
• ViewModel
• ViewModels : A Simple Example

17. What's Navigation component?

• Navigation
• Learn Jetpack Navigation

18. What is Jetpack Compose?

• Thinking in Compose
• Get started with Jetpack Compose

Architecture

19. What is Dependency injection?

• Dependency injection
• Dependency Injection
• Dependency Injection
• Dependency injection in Android

20. What types of design patterns do you know?

• Software design pattern
• Design Patterns

21. What do you know about Singleton pattern?

• Singleton pattern
• Singleton Method Design Pattern in Java
• Singleton Design Pattern

22. What do you know about Observer pattern?

• Observer pattern
• Observer Pattern | Set 1 (Introduction)

23. What do you know about MVVM pattern?

• Model–view–viewmodel
• Introduction to Model View View Model (MVVM)
• MVVM (Model View ViewModel) Architecture Pattern in Android
• Android Architecture Patterns Part 3: Model-View-ViewModel

RX

24. What Observables types do you know?

• Observable
• Reactive X: RxJava Data Flows: Observable, Flowable, Single, Maybe and Completable

25. What Schedulers types do you know?

• Scheduler
• RxJava — Schedulers — What, when and how to use it?
• Schedulers in RxJava

26. What is the difference between cold and hot observables?

• RxJava: Hot vs Cold Observable
• RxJava Ninja: Hot and Cold Observables

27. What is the difference between map and flatMap?

• When do you use map vs flatMap in RxJava?

Git

28. Describe branching strategies at your last workplace