Interview questions in Mobile Dev, page 14
Build and validate a login form with Form and GlobalKey
This tests Flutter's declarative form validation. A strong answer covers wrapping fields in a Form, using a GlobalKey<FormState>, calling validate on submit, and acting only on true.
What is remember in Compose and how do you use mutableStateOf?
This tests state survival across recompositions. Good answers say remember caches values across recompositions, pairs with mutableStateOf for observable state, and shows a counter. A red flag is mutableStateOf without remember, state resets per recomposition.
What is the purpose of `remember` in Jetpack Compose?
This tests your grasp of Compose's recomposition lifecycle. A good answer explains remember caches an object across recompositions, preventing state loss. It's used with mutableStateOf to hold the same state instance.
What is the purpose of the `remember` function in Compose?
This tests your grasp of recomposition. Explain that remember stores an object in the composition tree, preventing it from being re-initialized on every render. A red flag is confusing it with rememberSaveable, which survives configuration changes.
Offline-capable state architecture
Persist state locally, queue mutations while offline, apply optimistic updates, then sync and reconcile conflicts on reconnect.
What NavigationView limitations did NavigationStack solve for programmatic navigation?
This tests why NavigationView programmatic navigation was brittle. A strong answer contrasts scattered NavigationLink isActive booleans and broken multi-destination stacks against NavigationStack's unified path array. A red flag is calling it a simple rename.
What is a FocusNode and why is it useful in forms?
This tests your understanding of Flutter's imperative focus tree. A strong answer defines FocusNode as a persistent focus target, explains programmatic form navigation, and stresses initState creation and dispose.
Arrange UI elements vertically or horizontally in Jetpack Compose
Tests declarative layout fundamentals. Good answers name Column and Row, explain Modifier as an ordered chain of decoration and layout behavior, and note order changes semantics. Red flag: calling Modifier "just styling" or confusing it with LinearLayout.
How do you arrange UI elements in Jetpack Compose?
Tests your grasp of Compose's declarative layout model. Explain Row (horizontal) and Column (vertical) as the core layout composables. Define Modifier as the standard way to configure size, spacing, and behavior.
How to arrange UI elements in Jetpack Compose?
This tests your grasp of Compose's declarative layout basics. A good answer defines Column (vertical) and Row (horizontal) for structure, and Modifier for decoration, size, and behavior. A red flag is confusing Modifiers with simple styling.
Axios advantages over fetch
Axios auto-parses JSON, rejects on HTTP error status, and offers interceptors, timeouts, and cancellation out of the box.
How would you architect the app root for onboarding vs authenticated flows?
Tests window root swapping and state-driven architecture. Use a coordinator to own the window, swap rootViewController between nav and tab controllers on auth changes, and crossfade. Red flag: onboarding modal over tabs or keeping both hierarchies alive.
What gesture conflict exists in a scrollable list with horizontal swipes?
Tests Flutter's gesture arena and slop disambiguation. Diagonal motion triggers both vertical scroll and horizontal swipe; the axis whose delta exceeds touch slop first wins the arena. Red flag: claiming Flutter blocks inner gestures or fires both at once.
Explain Jetpack Compose recomposition, its triggers, and optimizations.
This tests grasp of Compose's reactive model. A strong answer defines recomposition as recomputing composables when state changes, notes State triggers it, and explains Compose skips unchanged subtrees via smart tracking.
Explain Recomposition in Jetpack Compose
This tests your core understanding of Compose's declarative model. Explain that recomposition is re-running composables when state they read changes. Mention that Compose optimizes by only recomposing the nearest scope and skipping composables with stable…
Explain Recomposition in Jetpack Compose
Tests your grasp of Compose's declarative model. A good answer defines recomposition, explains state-read triggers, and details how stability and positional memoization enable skipping. A red flag is assuming any state change redraws the entire UI.
Robust network error handling strategy
Classify errors as 4xx, 5xx, or connectivity; retry transient failures with backoff, surface actionable messages, and check NetInfo.
Design state-driven navigation for a conditional wizard in UIKit and SwiftUI
This tests separating navigation state from UI. Model the flow as a state machine enum, derive the stack from state, and unit test transitions in plain Swift. A red flag is imperative pushes inside views or view controllers.
Implement efficient async username validation in Flutter
Tests async field hygiene in Flutter. Outline: debounce 300ms, cancel inflight requests, decouple loading UI from errors, use reactive_forms async validators or manual streams. Red flag: API calls per keystroke without cancellation, loading treated as errors.
Describe state hoisting and its benefits in Compose
Move state to the caller, pass value and event lambda down, keep them stateless.
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