A hiring manager's question bank for Android developers — Kotlin, the activity and fragment lifecycle, coroutines, Jetpack Compose, and architecture. Built to separate people who can follow a tutorial from people who ship stable apps to millions of devices.
Hiring an Android developer means testing for a specific kind of discipline: writing code that behaves correctly across a lifecycle you do not control. Unlike a backend service, an Android app is constantly interrupted — the screen rotates, a call comes in, the OS kills your process to reclaim memory, the user backgrounds the app for three days and comes back expecting their state intact. A candidate who does not deeply understand the activity and fragment lifecycle will write code that leaks memory, loses state on rotation, or crashes when a configuration change destroys and recreates the activity. Beyond the lifecycle, modern Android is Kotlin-first, so you want fluency in null safety, coroutines and structured concurrency for async work, and increasingly Jetpack Compose for declarative UI. The strongest signal is architectural judgement: does the candidate keep logic out of activities and fragments, use a ViewModel that survives configuration changes, reason about the main thread versus background dispatchers, and think about memory, battery, and jank on real devices rather than a fast emulator? The questions below run from Kotlin fundamentals through the lifecycle and concurrency into UI and architecture. Pair a couple of lifecycle questions with one coroutine scenario and one "your app is janky and leaking memory" discussion, and you will quickly learn whether someone has shipped and maintained a production Android app or only built a sample.
Pick six to eight questions across two or three categories instead of running the whole list. Start with a Kotlin or Lifecycle question to set a baseline, then spend real time on a Coroutines & Async scenario and one Architecture or performance discussion. Follow every clean answer with "what happens on a configuration change?" or "which thread does that run on?" — the follow-up is where production experience shows.
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