Android development is a highly sought-after skill in today’s job market. As companies continue to expand their mobile offerings, there is increasing demand for talented Android developers to build the apps we use every day.
Android developers design, build, and maintain mobile applications running on the Android operating system. It is their job to write clean, well-organized code that ensures apps function properly and provide a great user experience.
The role requires strong programming skills in Java and/or Kotlin, as well as knowledge of core Android SDK components. Developers must also understand REST APIs and databases to integrate back-end services into apps. Familiarity with Android Studio, version control systems like Git, and agile software methodologies is also important.
In an interview setting, companies want to assess your technical abilities and problem-solving skills. They may ask you to whiteboard code, discuss approaches to complex tasks, or quiz you on Android architecture and APIs. Having a solid grasp of Android fundamentals is key.
I’ve compiled 10 of the most common Android developer interview questions below, along with advice on how to demonstrate your knowledge. Preparing responses to questions like these will help you tackle the technical portion of your interview with confidence.
Top 10 Android Developer Interview Questions
1. What are the core components of Android architecture?
This question tests your understanding of the basic building blocks that make up the Android operating system. Be sure to cover the key components in your response:
- Linux Kernel – Provides core system functionality like process management and memory management
- Android Runtime – Includes the Dalvik virtual machine and core libraries that enable developers to write Android apps using Java/Kotlin
- Native C/C++ Libraries – Key libraries written in native code that handle different device capabilities
- Application Framework – Provides high-level Java classes and interfaces for app development and access to components like Activities, Services, ContentProviders, etc.
- Applications – Apps written in Java/Kotlin that run within the Android Runtime using the application framework and native libraries
Highlighting these core architectural layers demonstrates you grasp the overall Android system.
2. Explain Android activity lifecycle and common lifecycle methods.
Activities are key building blocks of Android apps, so expect questions about their lifecycle. Make sure to cover:
- The activity lifecycle from Created to Destroyed states
- Key callback methods like onCreate(), onStart(), onResume(), onPause() etc. and when they get called
- The importance of saving/restoring state in onSaveInstanceState() and onRestoreInstanceState()
- How activities can be destroyed and recreated by the system during configuration changes
Discussing the activity lifecycle and associated methods shows you understand the complex state transitions that take place and how to properly save/restore state.
3. How does Android handle concurrency with AsyncTask and IntentService?
Mobile apps often need to perform background tasks without blocking the UI thread. Your interviewer wants to assess your understanding of two key ways Android handles concurrency:
- AsyncTask – Introduces asynchronous processing in apps by allowing you to define tasks in a simplified worker thread. Explain how AsyncTask enables loads in separate thread but delivers results on UI thread.
- IntentService – An extensible service class that handles asynchronous requests on a single background thread. Highlight how it queues up requests and starts a worker thread, delivering results on main thread.
Demonstrate where each should be used and benefits/drawbacks of both approaches. This shows you grasp mobile concurrency challenges.
4. What is the role of Android manifest and how is it used?
The manifest file is essential in all Android apps, so interviewers may ask about:
- Purpose of manifest – Declares app components like activities, services, broadcast receivers, etc. and provides essential app metadata
- Key manifest elements – permissions, intents, metadata like app name, icon, SDK/API level
- How manifest role differs from build.gradle – manifest provides runtime info, gradle configures build process
- Typical tasks like declaring components, permissions, API access
Concisely explaining the manifest’s vital runtime configuration role displays your knowledge.
5. How do you support different screen sizes and densities in Android?
Supporting Android’s diversity of devices and displays is crucial. Be sure to highlight:
- Using DP units for density independence and avoiding hard-coded pixel sizes
- Leveraging size-qualified resources (e.g. layout-sw600dp) and multiple layouts
- Designing adaptive UIs with constraints and Flexbox
- Adjusting bitmap drawables for high/low DPIs via density qualifiers (e.g. drawable-hdpi)
- Setting scrollable containers, limits on image sizes, and drawable scaling attributes
Demonstrating these techniques will show you can build responsive cross-device app UIs.
6. What are Fragments and how are they used?
Fragments are important UI components for adapting to tablets/larger screens. Be sure to cover:
- Fragments represent reusable sub-sections of app UI with their own lifecycle
- Used in ViewPager for swipe views, displayed in FragmentTransactions
- Communicate through hosting activity which manages FragmentBackStack
- Advantages over activities for tablet support and reusability
Explaining fragments’ benefits for modular, responsive design will showcase your grasp of Android tablets and multi-pane UIs.
7. How can data be saved in Android apps?
Apps often need to persist data locally or share data between components. Discuss various options:
- SharedPreferences – Key-value storage for primitive data
- SQLite databases – For structured relational data storage and queries
- Room persistence library – Simplifies SQLite with object-mapping
- Filesystem – Direct file storage for larger data like images, videos, etc.
- ContentProviders – To share data between apps and app components
Highlighting appropriate uses of each technique demonstrates you know how to locally save and share persistent app data.
8. What is dependency injection and how is it used in Android?
Dependency injection (DI) is a key technique for improving code testability and maintainability. Be sure to mention:
- Main goals of DI – decouple dependencies, increase modularity, simplify testing
- Dagger2 for constructor dependency injection – annotates constructor args as injectable
- @Inject annotation to request dependency objects
- @Module classes provide dependencies
- @Component interfaces connect objects with their dependencies
Discussing DI in this implementation-agnostic way displays your high-level understanding, even if you haven’t used Dagger specifically.
9. How would you improve performance in an Android application?
Performance tuning is an important skill for Android developers. Make sure to highlight techniques like:
- Identifying slow code paths with profiling tools
- Moving long-running tasks to background threads
- Adding pagination or infinite scrolling to lists/RecyclerViews
- Lazy loading large bitmaps or images only as needed
- Minimizing UI refreshes using ViewHolder pattern
- Enabling hardware acceleration for animations/graphics
- Simplifying layout hierarchies and using ConstraintLayout
Being able to intelligently discuss performance considerations demonstrates your ability to optimize real-world apps.
10. Describe the app publishing process on the Google Play Store.
Releasing apps to the Play Store requires following specific processes. Be sure to outline:
- Configuring Play Console with app name, graphics, contact info
- Building release-ready APKs, signing with release key
- Drafting compelling descriptions and screenshots
- Defining pricing, beta channels, staged rollouts if needed
- Submitting app for review based on Google policies
- Publishing app to Production or closed tracks after approval
- Using Play Console to track statistics and user feedback after launch
Walking through the steps shows you understand the requirements for public app distribution.
Conclusion
With strong responses to questions like these, you can demonstrate the skills Android employers are looking for in terms of technical knowledge, problem-solving, and practical development techniques. Use these examples to get comfortable discussing Android concepts, components, and tools.
Bringing real-life examples and code snippets to illustrate your answers is also helpful. And if you’re stumped on a question, don’t be afraid to say you’d need to look up a specific detail, then explain how you would research it.
Preparing for the types of questions here will help you convey your abilities – and land you the Android job you want! Let me know if you have any other questions to add to the list. Good luck with your upcoming interviews!
