🔄 Mastering StateFlow in Android Development

With the rise of Kotlin Coroutines, StateFlow has become an essential tool in modern Android architecture. It provides a reactive, predictable, and lifecycle-agnostic way to manage UI state in ViewModels.

In this blog, we’ll cover:

• What is StateFlow?
• StateFlow vs LiveData
• When to use StateFlow
• Key features and syntax
• Code examples
• Best practices
• Common mistakes

💡 What is StateFlow?

StateFlow is a hot, state-holder flow introduced in Kotlin Coroutines 1.4+. It behaves like a LiveData, holding the latest value and notifying all collectors when the value changes.

```kotlin private val _uiState = MutableStateFlow(“Hello”) val uiState: StateFlow = _uiState 🆚 StateFlow vs LiveData

Feature StateFlow LiveData Lifecycle-aware ❌ No (use with lifecycleScope) ✅ Yes Coroutine-native ✅ Yes ⚠️ No (requires conversion) Holds latest value ✅ Yes ✅ Yes Cold/Hot 🔥 Hot ❄️ Cold Backpressure ✅ Respects coroutines ⚠️ Limited 🚀 When to Use StateFlow? UI state management inside ViewModels

Two-way data binding with Compose

Form validation and input fields

Loading/error/success screen states

Internal state handling, replacing LiveData

🧬 StateFlow Example kotlin Copy Edit class MyViewModel : ViewModel() { private val _counter = MutableStateFlow(0) val counter: StateFlow = _counter

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fun increment() {
    _counter.value++
} } In Compose: kotlin Copy Edit @Composable fun CounterScreen(viewModel: MyViewModel) {
val count by viewModel.counter.collectAsState()

Button(onClick = { viewModel.increment() }) {
    Text("Count: $count")
} } 📌 Best Practices Expose as read-only using asStateFlow()

Use collectAsState() in Compose

Use with lifecycleScope in XML-based UI

Avoid using for events (use SharedFlow instead)

❗ Common Mistakes ❌ Collecting in wrong lifecycle state

❌ Using StateFlow for navigation/toasts

❌ Emitting from outside ViewModelScope