Android Dev Hub

Preparing for an Android interview? You probably don't need another 2,000-word lecture on Flow. You need to remember one thing quickly: StateFlow → What is the current state? SharedFlow → What happened? That simple question will help you choose between them in many interview situations. StateFlow vs SharedFlow — Quick Revision StateFlow SharedFlow Represents current state Broadcasts values/events Always has a current value Does not require an initial value New collector gets the latest value Replay is configurable Always keeps one latest value Can replay multiple previous values Great for UI state Useful for events and broadcasts Memory trick: StateFlow = State SharedFlow = Share Don't memorize the table. Ask yourself: "Does my UI need to know the current condition, or do I need to tell collectors that something happened?" 1. What is StateFlow? StateFlow is a hot flow that always holds a current value. A new...

One question I see repeatedly in Android interviews and developer forums is: "Is Clean Architecture part of MVVM?" The short answer is no. MVVM and Clean Architecture solve different problems. MVVM is a presentation architecture that organizes your UI, while Clean Architecture organizes your entire application into separate layers with clear responsibilities. The confusion happens because many Android projects combine both. A project may use MVVM for the presentation layer and Clean Architecture for the overall application structure. In this article, I'll explain the difference with simple diagrams, practical Android examples, and show when you should use only MVVM and when combining MVVM with Clean Architecture actually makes sense. Diagram Android App ┌─────────────────────┐ │ View │ │ Activity/Compose │ └─────────┬───────────┘ │ ▼ ┌───────────────┐ ...

MVVM vs Clean MVVM   Which Architecture Should You Choose in 2026? Introduction One of the most common questions I hear from Android developers is: "Should I use MVVM or Clean MVVM?" I have been developing Android applications for more than seven years, and I have worked on everything from small utility apps to enterprise-level products used by thousands of users. Interestingly, many projects start with simple MVVM and later move toward Clean MVVM as the application grows. The confusion usually comes from the fact that both architectures use ViewModel, Repository, Coroutines, Flow, and modern Android libraries. At first glance, they look very similar. However, the differences become obvious when the project becomes larger, multiple developers start contributing, and business logic becomes more complex. In this article, I will explain both architectures using practical examples, discuss their advantages and drawbacks, and share what has worked for me in real projects. What is ...

Preparing for Android developer interviews in 2026 can feel overwhelming—not because the concepts are complex, but because topics are scattered across Kotlin, Coroutines, Jetpack Compose, and System Design. This complete roadmap organizes the core topics you will be tested on during technical screens and coding rounds in 2026. Use this guide as: A quick revision checklist before your interview A structured learning roadmap A reference guide for core Android concepts 1. Kotlin Basics & Core Syntax val vs var val : Read-only reference (immutable pointer). var : Mutable reference (can be reassigned). Rule of thumb: Always default to val for thread safety and defensive programming. lateinit vs lazy // Used for non-null var properties initialized later (e.g., Dependency Injection) lateinit var repository: UserRepository // Thread-safe initialization triggered only on first access val database: AppDatabase by lazy { AppDatabase.getInstance(context) } ...

A "FATAL EXCEPTION: main" error occurs when there is an issue with the main thread of your application, causing it to crash. This can happen for a number of reasons, such as: 1)NullPointerException: This occurs when you try to use an object that is null, instead of instantiating it first. 2)Resource not found: This occurs when the app cannot find a resource it needs, such as an image or layout file. 3)ClassNotFoundException: This occurs when the app cannot find a required class. 4)Stack Overflow:  This occurs when a method calls itself too many times and the call stack becomes full. 5)Out of Memory Error: This occurs when the app runs out of memory and can't allocate more. To troubleshoot the issue, you can do the following: 1)Check the logcat for any error messages, this will give you more information about the specific cause of the error. 2)Look for any missing resources or classes in your code. 3)Check for any null pointer exceptions by looking for instances where you...