Alex Chen

Android performance optimization ensures smooth 60fps UI and efficient resource usage. I use Android Profiler to monitor CPU, memory, network, and energy. Layout Inspector identifies overdraw and deep view hierarchies. Systrace captures system-level t

ProGuard and R8 shrink, obfuscate, and optimize Android apps for release builds. R8 is the default tool, combining shrinking and desugaring. I configure rules in proguard-rules.pro—keeping classes used by reflection, serialization, or native code. -ke

Deep links open specific app content from external sources. I configure intent filters in AndroidManifest with URL schemes—http, https, or custom. App Links verify ownership via assetlinks.json on your domain, providing seamless no-dialog opening. Int

Google Play Billing enables selling digital content and subscriptions. I integrate the Play Billing Library and initialize BillingClient with PurchasesUpdatedListener. Query available products with queryProductDetailsAsync(). Launch purchase flow with

Services run background operations without UI. I extend Service and override onStartCommand() for started services or onBind() for bound services. Foreground services use startForeground() with ongoing notification, required for long-running tasks vis

Notification channels give users granular control over notification types on Android 8+. I create channels with unique IDs, names, and importance levels. Channels group related notifications—messages, reminders, promotions. Users control vibration, so

App Widgets display app content on the home screen. I extend AppWidgetProvider, a BroadcastReceiver subclass handling widget lifecycle. onUpdate() refreshes widget UI, onEnabled() initializes on first widget added, onDisabled() cleans up when last rem

BroadcastReceiver responds to system-wide or app-specific events. I register receivers statically in AndroidManifest or dynamically with registerReceiver(). The onReceive() method handles broadcasts—network changes, battery status, boot completed, SMS

LiveData transformations create derived data streams reactively. Transformations.map() converts values—like mapping User to username string. Transformations.switchMap() switches LiveData sources based on input, enabling dynamic queries. MediatorLiveDa

Custom ViewGroups enable specialized layout behavior beyond standard containers. I extend ViewGroup and override onMeasure() to measure children and onLayout() to position them. measureChild() or measureChildWithMargins() determines child sizes. Layou

DownloadManager handles long-running downloads with notification progress. I create DownloadManager.Request with URI and destination. setNotificationVisibility() controls progress notifications. Headers customize HTTP requests. Network type requiremen

BiometricPrompt provides secure authentication via fingerprint, face, or iris. I create BiometricPrompt with callback handling success, error, and failure. PromptInfo configures title, subtitle, description, and allowed authenticators. Negative button