kotlin

Paging 3 loads large datasets incrementally with network and database support. I create a PagingSource implementing load() method to fetch pages. RemoteMediator orchestrates network and database, fetching from API and caching locally. Pager configurat

Firebase Cloud Messaging (FCM) delivers push notifications across platforms. I extend FirebaseMessagingService and override onMessageReceived() to handle incoming messages. Device tokens obtained via FirebaseMessaging.getInstance().token register with

RecyclerView displays large datasets efficiently with view recycling. I create a ViewHolder to cache view references and an Adapter to bind data. DiffUtil calculates minimal updates using areItemsTheSame and areContentsTheSame callbacks, improving per

WorkManager schedules deferrable, guaranteed background work. I create Worker or CoroutineWorker subclasses with doWork() method. Constraints specify when work runs—network type, charging status, battery level. One-time requests use OneTimeWorkRequest

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

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

EncryptedSharedPreferences secures simple key-value data using Android Keystore. I create instances with EncryptedSharedPreferences.create() specifying encryption schemes. The master key uses MasterKeys or MasterKey.Builder for automatic key generatio

Glide efficiently loads and caches images from network, disk, or resources. I use Glide.with(context).load(url).into(imageView) for basic loading. Transformations apply effects—centerCrop(), circleCrop(), RoundedCorners(). Placeholders show during loa

ExoPlayer is a flexible media player supporting diverse formats and protocols. I create instances with ExoPlayer.Builder(context).build() and configure with MediaItem. Setting player.setMediaItem() and player.prepare() initializes playback. PlayerView

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

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

MVVM separates concerns in Android apps—Model holds data, View displays UI, ViewModel mediates with business logic. ViewModels survive configuration changes, preventing data loss during rotation. I use ViewModel class with viewModelScope for coroutine