Android Lifecycles Masterclass

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Understand how Android creates a Linux process for each app, providing an isolated execution environment and memory sandbox, with system processes handling core tasks.

Explore how Android creates a Linux process when an app launches and runs in the background. See how swiping from recents kills the process and relaunch creates a new one.

Learn how Android application class provides one instance per app process, at launch, accessible from all components, and replaced by a subclass in the manifest to share logic and state.

Explore how application.onCreate initializes one-time global setup, including timber logging and a process lifecycle observer to detect foreground and background transitions.

Understand the Android application life cycle as creation, destruction, and system callbacks, and how the application object initializes on first launch and persists with global objects.

Master the activity life cycle by learning onCreate and onDestroy: call super, setContentView, initialize fields in onCreate, and unregister listeners in onDestroy when needed.

Explore the Android activities back stack as a last-in, first-out structure where foreground activities push back-stack items and back navigation pops them. Android versions 11 and 12 change root behavior.

Explore how on start and on stop manage visibility, not just foreground status, in Android activities, register observables, refresh the user interface, and pause work when the activity loses visibility.

Explore the Android activity lifecycle by learning when onResume and onPause are invoked, how they control interactivity and animations, and how to manage resources with overlays.

Explore the difference between overlapping and non-overlapping lifecycle phases, and why using on resume and on pause can cause false background detector signals during started transitions.

Learn how memory leaks arise when app components hold references after destruction, and how lifecycle practices like registering and unregistering listeners prevent leaks in Android apps.

Centralize Android activity lifecycle logging by implementing an activity lifecycle callbacks inner class to log on created and started events, using Timber tags, and compare with per-activity logging.

Explore the Android activity life cycle by listing onCreate, onStart, onResume, onTopResumedActivityChanged, onPause, onStop, and onDestroy, including when they run and their purposes.

Explore the fragment lifecycle and how fragments, as composable ui controllers embedded in activities, enable master-detail layouts and reusable, multi-fragment interfaces on tablets.

Showcases adding and removing a fragment in a fragment host activity with the fragment container view, using the support fragment manager and tag-based removal to illustrate the fragment life cycle.

Override onViewCreated to manipulate the view hierarchy after onCreateView, inflating the layout in onCreateView and initializing view-related fields in onViewCreated.

Understand fragment lifecycle methods onCreate, onDestroy, onStart, onStop, onResume, and onPause, and their activity counterparts. Learn when to initialize dependencies, register observers, and start or pause flows.

Explore the fragment lifecycle in practice within the tutorial app, seeing how add, replace, and remove trigger fragment lifecycle methods like onCreate, onCreateView, onStart, and onResume.

Explore how fragments back stack governs lifecycle during navigation, showing how adding transactions to the back stack preserves fragment instances while destroying their views, and how popping restores prior states.

Understand how activity and fragment lifecycles inter-couple, observe the order of callbacks like onPause, onStop, and onDestroy, and avoid writing code that depends on the enclosing activity state.

Learn how the fragment view lifecycle differs from activities, including how fragments release and recreate their view hierarchies, and how clearing view references in onDestroyView optimizes memory.

Explore how fragment view lifecycles recreate views, weigh memory optimization against processing overhead, and learn to cache the root view to avoid reinitializing the view on subsequent calls.

Understand that on attach and on detach are legacy fragment lifecycle methods tied to retained fragments. Ignore these methods in modern app development, as retained fragments are deprecated.

Register fragment lifecycle callbacks with the fragment manager to log fragment lifecycle events, including pre-attached and pre-created stages, and review how these callbacks auto-unregister with activity destruction for debugging.

Explore fragment navigation libraries for Android, comparing frag nav, simple stack, and the official navigation component, and learn to replace manual fragment transactions with robust, multi-stack navigation.

Explore configuration changes in Android apps by observing orientation and split-screen changes, and see how activities and fragments are destroyed and recreated with new window parameters.

Understand the default configuration change flow in Android, where the system saves state and recreates foreground activities and fragments. This simple approach minimizes work and ensures a clean state.

In the Android lifecycles masterclass, fix the background detection code by delaying on stop to handle configuration changes, aligning the manual detector with the app lifecycle observer.

Explore fragment manager state management during configuration changes, prevent fragment duplication by checking saved instance state for null, and understand automatic fragment recreation by the system.

Discover how view state is preserved during configuration changes by assigning IDs to standard Android views, enabling automatic restoration. Custom views may require additional work to support restoration.

Preserve custom state across configuration changes using global objects like the application object, or save and restore with on save instance state in activities and fragments, including view models.

Explore manual handling of configuration changes in Android using the manifest configChanges and onConfigurationChanged, revealing pitfalls and tricky bugs and how saved state can improve reliability.

Explore how Android handles configuration changes, including orientation, by destroying and recreating foreground components. Learn how IDs, fragment manager and unsafe instance state help preserve essential data.

Learn how an observable viewmodel exposes a counter and notifies observers, preserving state across rotations while onStart registers and onStop unregisters to prepare for a LiveData demo.

Discover how view models align with activity or fragment lifecycles and how onCleared cancels coroutines to prevent memory leaks when the UI is destroyed.

Explore how Android kills a process and how the save and restore flow preserves and restores state across relaunches into a new process.

Learn why memory management in Android preserves background apps' state and how the save and restore flow handles automatic navigation state and manual custom state restoration.

Discover how to test the save and restore flow in Android lifecycles masterclass by exploring multiple approaches, overcoming fragmentation across devices, versions, and emulators.

Explore Android lifecycles by testing save and restore flows with background process limit, showing how Android proactively kills background processes and how navigation state is restored.

Learn to test save and restore by forcing a cached process via developer options, stopping the app, and observing the navigation state restoring to the second activity.

Learn how to test save and restore with adb by terminating your app process using force stop, root kill, or run as, and observe state restoration.

Learn how the Android save and restore flow in activities preserves or loses view state, including RecyclerView, and apply onSaveInstanceState and bundles to preserve custom state.

Fragments mirror activities in save and restore flows; most views restore automatically with unique IDs, but some like RecyclerView require explicit handling, and navigate only if savedInstanceState is null.

Demonstrates how a view model preserves state during config changes but not across save and restore by default; uses save state handle to store and recover counter, akin to bundle.

Explore how global objects within the application object behave during save and restore, using a foreground count log to show state lost after process death.

Persist the global state to a persistent medium such as shared preferences or a database. Evaluate synchronous versus asynchronous restoration and cache invalidation to avoid race conditions when preserving state.

Explore how mutable static state, including singletons, behaves under save and restore, and compare it to global state, guiding strategies to preserve or adapt this state across flows.

Compare save and restore with configuration changes to reveal state lost in activities, fragments, and view model. Preserve state with unsaved instance state and test to avoid bugs.

Learn how Android's save and restore handles process death by terminating background processes, saving automatic state, and requiring manual restoration of custom state, with differences from configuration changes.

Learn to add an android service, register it in the manifest, start and stop it with intents, and manage lifecycle via onCreate, onStartCommand, and onDestroy.

Explore Android background work restrictions and why regular services cannot reliably run tasks when the app isn’t visible, and how foreground services maintain execution with a notification.

Master how to implement a foreground service in Android by using startForegroundService, providing a notification, and handling onStartCommand with startForeground, then manage permissions and service types.

Discover how Android services survive configuration changes, repositioning a screen overlay by overriding onConfigurationChanged and refreshing the overlay without restarting the service.

Explore how Android services restart after process death by choosing onStartCommand behavior (start sticky, start not sticky, or start redelivery) and service type, including foreground and overlay services.

Fix a foreground service lifecycle bug by moving cleanup from onStart to onDestroy, ensuring the service manager reflects the correct state even when stopped via developer options.

Explore Android life cycles as the creation and destruction timing of objects with system invoked callback methods, and understand why they are fundamental, complex, and a common source of bugs.

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