Android Developer Interview
Questions & Answers

onCreate → onStart → onResume (foreground) → onPause → onStop → onDestroy. Common mistakes: doing heavy work in onCreate (blocks UI), not saving state in onSaveInstanceState (state lost on rotation), registering listeners in onResume without unregistering in onPause (memory leaks), and treating onDestroy as reliable cleanup (it is not guaranteed to be called). Modern Android: ViewModel survives configuration changes — use it to separate UI state from lifecycle.

WorkManager for guaranteed deferrable background work (syncs, uploads) — it survives process death and device restarts. Coroutines with lifecycleScope/viewModelScope for work tied to a UI component's lifetime. Foreground services for ongoing user-aware tasks (music playback, navigation). Never use long-running AsyncTask (deprecated) or background Service for deferrable work — battery optimisation kills them. Doze mode and App Standby are the constraints you are designing around.

MVVM with Repository pattern: View observes ViewModel LiveData/StateFlow, ViewModel calls Repository, Repository abstracts local (Room) and remote (Retrofit) data sources. Dependency injection with Hilt for testability. Single Activity with Fragment navigation or fully Composable navigation. The goal is a unidirectional data flow where the UI layer never directly accesses the data layer — this makes testing and refactoring tractable at scale.

ANR occurs when the main thread is blocked for over 5 seconds (user input) or 10 seconds (broadcast receiver). Pull the ANR trace from the device (/data/anr/traces.txt) or from Android Vitals in Play Console. The trace shows the main thread stack at the time of the ANR — look for synchronous disk I/O, network calls, or a deadlock. Fix: move blocking operations to a background coroutine, use async APIs, and never hold a lock across a UI operation.

Compose: declarative UI, less boilerplate, easier to build dynamic UIs, better interop with Kotlin coroutines for state management. XML: mature tooling, ViewBinding, required for some third-party libraries not yet Compose-compatible. Compose is the current direction for new development; XML knowledge is still required for maintaining existing apps. In a mixed codebase, the AndroidView composable bridges Compose and the View system. Strong candidates have production experience in both.

Structure your answer as a 60-second professional narrative: where you have been (your background), what you have done (your strongest achievement), and where you are going (why this role). Lead with your most relevant experience, not your entire career history. End with why you are excited about this specific opportunity.

Choose a genuine weakness that you have actively worked to improve. The structure is: name the weakness → show self-awareness of its impact → describe the concrete step you took to address it → show the improvement. Never say "I work too hard" — interviewers recognise this as evasion and it damages your credibility.

Use the STAR method (Situation, Task, Action, Result) but add a fifth element: what you learned. Choose a real failure, not a disguised success. Show you can take responsibility without making excuses, and demonstrate that the lesson changed your behaviour in a specific, verifiable way.

Be honest but constructive. Acceptable reasons: seeking greater scope, new challenge, skills you can not develop in the current role, or company-level changes (restructuring, direction shift). Never speak negatively about your current employer or manager — it signals you will do the same to the prospective employer in future conversations.

Describe the conflict specifically, show that you sought to understand the other person's perspective, and explain the resolution approach you took. Interviewers are assessing your emotional intelligence and whether you escalate or resolve. Avoid stories where you were right and they were wrong — choose a story where both parties grew.

Describe your specific prioritisation system: impact × urgency matrix, stakeholder alignment, or a specific tool or process you use. Then give an example where you applied it under real pressure. Show that your system is systematic rather than reactive, and that you communicate proactively when priorities change.

Choose an achievement that is specific, measurable, and relevant to the role. Lead with the result ("I reduced our error rate by 40% in 90 days"), then explain the context, challenge, and what you specifically did that drove the result. Show your ownership and impact, not just your team's work.

Be honest about your ambitions while showing that this role is a genuine step in that direction — not a stopgap. Hiring managers want to invest in people who will grow with the organisation. Show that your 5-year goal requires the specific skills and experience this role provides, making your ambition an asset for both sides.

Research before the interview and make the answer specific: cite their product, a recent company development, something about their culture or team, or a professional aspect of this particular role that matches your goals. Generic answers ("I love your values") signal you did not do the research. Specific answers signal genuine interest.

Always have 3–5 questions prepared. Ask about the biggest challenge in this role, what success looks like in the first 90 days, how the team operates, and the interviewer's own experience at the company. Never ask about salary, benefits, or holidays in a first interview. Questions show interest, strategic thinking, and that you care enough to have done research.