Android Developer interview questions and answers.

Questions

Technical questions to practise out loud

1. 01

   What is structured concurrency in Kotlin coroutines?

   Structured concurrency binds child coroutines to a parent scope, so completion, cancellation, and failure have a defined owner; use lifecycle-aware scopes and avoid unowned GlobalScope work.

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2. 02

   How do ViewModels work with the Android lifecycle?

   A ViewModel retains screen state across configuration changes and is cleared when its owner finishes; it should expose UI state and launch work in viewModelScope without holding Activity or View references.

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3. 03

   What triggers recomposition in Jetpack Compose?

   Compose recomposes functions that read state when that state changes; stable inputs, correctly scoped state, keys, and derivedStateOf reduce unnecessary work without suppressing required UI updates.

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4. 04

   How do you find Android memory leaks?

   Find Android leaks by reproducing lifecycle transitions, watching retained objects with LeakCanary or a heap dump, then tracing the reference chain—commonly static state, callbacks, adapters, or coroutines.

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5. 05

   How do you design an offline-first Android app?

   An offline-first app reads from a local source of truth, synchronises with the network in the background, records pending writes, and defines conflict resolution, retry, freshness, and user-visible sync state.

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6. 06

   How do you handle networking on Android?

   Android networking needs typed API contracts, timeouts, cancellation, retry only for transient idempotent work, mapped errors, authentication refresh, secure transport, and repository-level caching or persistence.

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7. 07

   How do you structure Android navigation?

   Model navigation as explicit destinations and arguments, keep navigation decisions outside reusable UI, restore state after process death, and handle deep links and back-stack behaviour as tested product flows.

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8. 08

   What is your Android testing strategy?

   Test Android logic on the JVM where possible, use Compose or instrumentation tests for platform interaction, isolate repositories, control dispatchers and clocks, and keep a small end-to-end set for critical journeys.

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9. 09

   How do you improve Android app performance?

   Improve Android performance by measuring startup, frame timing, memory, battery and network with Macrobenchmark, profiler and traces; fix main-thread blocking, excessive recomposition, allocations, or oversized work.

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10. 10

    How do you store sensitive data on Android?

    Store sensitive Android data minimally, use platform-backed encrypted storage or Keystore keys, never hard-code secrets, protect exported components, validate deep links, and assume a compromised client cannot keep server secrets.

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