Interview questions in Mobile Dev, page 9
What is ADB and what are two common commands you use?
Tests your hands-on familiarity with the core Android toolchain. Define ADB's client-server architecture, then explain adb install for APKs and adb logcat for logs. A red flag is being unable to name specific commands or only knowing IDE buttons.
What is the Android Debug Bridge (ADB)?
This tests practical command-line proficiency and understanding of the host-device link. A good answer defines the client-server-daemon architecture and gives two commands like adb install and adb logcat.
ScrollView versus FlatList for long lists
ScrollView mounts all children at once; FlatList virtualizes, rendering only on-screen items plus a buffer. Use ScrollView for small/fixed content, FlatList for long/dynamic data.
Explain the difference between Gradle build types and product flavors.
If you know build types are how an app is built—debug versus release—while flavors are what is shipped, like free versus paid. Variants are the Cartesian product.
Integrate SwiftUI into UIKit and wrap UIKit for SwiftUI
Tests bridging architecture between UIKit and SwiftUI using UIHostingController and UIViewRepresentable. A strong answer names hosting controllers for SwiftUI in UIKit, representable protocols for UIKit in SwiftUI, and lifecycle hooks.
Explain lifting state up with a concrete scenario and benefits
Tests moving state to a common ancestor when siblings share data. Outline: pick two siblings, hoist state to the parent, pass values and callbacks down. Red flag: mutating a sibling via GlobalKey or choosing Provider before proving the parent cannot own it.
Explain Gradle Build Types vs. Product Flavors
Tests your grasp of Gradle's build matrix. A great answer defines build types for lifecycle (debug/release) and product flavors for user-facing versions (free/paid), then explains how they combine into variants.
Gradle Build Types vs. Product Flavors
This tests your understanding of Gradle's build matrix for creating different app versions. A great answer defines build types (how it's built) vs. flavors (what is built) and explains that variants are the cross-product. A red flag is confusing their roles.
FlatList data, renderItem, and keyExtractor
Data is the array, renderItem maps each item to a component, keyExtractor returns a stable unique key letting React reconcile and reuse rows.
How does Auto Layout resolve constraints?
Auto Layout solves a system of prioritized linear equations; intrinsicContentSize is a view's natural size; hugging resists growing, compression resistance resists shrinking.
Explain the lifecycle of a State object
List initState through dispose, emphasizing didUpdateWidget reacts to parent config changes.
Which Android Studio Profiler tool diagnoses high memory usage and leaks?
Heap dump, check retained size for leaked Activities, trace reference chains to root retainer.
How do you diagnose a memory leak using the Android Studio Profiler?
This tests your practical skill with the Android Memory Profiler, not just theory. A great answer involves capturing a heap dump, filtering for unreachable objects, and inspecting the reference tree to find the leak's source.
How do you diagnose a memory leak with Android Studio Profiler?
This tests your systematic process for debugging memory issues. A good answer outlines using the Memory Profiler, forcing GC, capturing heap dumps, and analyzing object references. A red flag is just naming the tool without explaining the 'how'.
Diagnosing slow FlatList scroll and blank cells
Memoize renderItem and items, supply getItemLayout for fixed heights, tune windowSize, maxToRenderPerBatch, initialNumToRender, and removeClippedSubviews; profile first.
How do you build a custom SwiftUI Layout?
Conform to Layout, implement sizeThatFits to report the container size for a proposal, and placeSubviews to position each subview using its measured size.
What are Keys in Flutter and why are they critical?
Tests widget identity during reconciliation. Keys let Flutter distinguish moved widgets from changed data; without ValueKeys, ReorderableListView leaves state at old positions, e.g., a checkbox swap. Red flag: calling them performance tools.
How do you manage API keys across Gradle build variants securely?
Gitignore a properties file, load it in build.gradle, map secrets to BuildConfig or manifest placeholders by flavor, and commit safe defaults.
Managing Sensitive Information in Gradle Builds
Tests secure credential handling in Android builds. A good answer uses a git-ignored .properties file, the secrets-gradle-plugin to parse it, and accesses keys via BuildConfig. A red flag is storing keys directly in build.gradle or committing them.
How would you manage API keys in Gradle without version control?
Tests secure credential handling in Android builds. A good answer proposes the Secrets Gradle Plugin, which reads from an untracked properties file and exposes keys via BuildConfig, while also noting this doesn't protect against APK decompilation.
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