Coroutines & Concurrency Mastery ⚡🧵

A strict rulebook to prevent thread-blocking, memory leaks, and lost UI events in modern Android applications.

⚡ When to Use

• ViewModel Logic: Launching coroutines for network/database requests.
• One-Time UI Events: Showing Snackbars, Toasts, or Navigation triggers.
• Parallel Work: Running multiple non-blocking tasks.

🚦 Rule 1: The UI Event Dilemma (StateFlow vs Channel)

You must explicitly distinguish between UI State (things that persist on rotation) and UI Events (things that happen once, like a Toast or Navigation).

• UI STATE: Use MutableStateFlow.
• UI EVENTS: Use an un-buffered Channel exported as a Flow. NEVER use SharedFlow with replay = 0 or MutableStateFlow for one-time events, because if the app rotates, the event might be dropped or replayed twice.