Coroutines Lifecycle — Droidly Explainer

30-second explainer

Coroutine
Lifecycle

How launch, suspend & cancel really work

▶ Auto-playing

MyViewModel.kt

          class MyViewModel : ViewModel() {
           
            init {
              viewModelScope.launch {
                // 🚀 coroutine body
                loadDashboard()
              }
            }
          }
        

viewModelScope

Tied to ViewModel lifecycle — auto-cancelled when ViewModel is cleared

.launch { }

Starts a new coroutine on Main dispatcher. Non-blocking & structured

MyViewModel.kt

            viewModelScope.launch {  // Main thread ↓
              val data = withContext(Dispatchers.IO) {
                repository.fetchData()  // IO thread — suspend
              }  // resumes on Main ↑
              _state.value = data
            }
        

Main

──suspends──▶

Dispatchers.IO

──resumes──▶

Main

Never blocks UI 🎯

What happens when you leave the screen?

🚪 ViewModel.onCleared()

User navigates away

↓

⚡ viewModelScope.cancel()

Scope is cancelled

↓

✅ CancellationException thrown

Coroutine exits safely

Key Takeaways 🎓

🔗

viewModelScope auto-cancels — zero manual cleanup needed

⏸️

suspend pauses the coroutine, not the thread — UI stays smooth

🧵

Use Dispatchers.IO for network/disk, Default for CPU-heavy work