Intermediate 8 min readKotlin 2.0
Kotlin SharedFlow — Events and Broadcast Streams
SharedFlow is a hot flow for broadcasting values to multiple collectors. Use it for one-time UI events; use StateFlow for state.
What You Will Learn
- Create MutableSharedFlow
- Emit events with emit()
- Configure replay and buffer
- Compare SharedFlow vs StateFlow
- Model one-time UI events safely
SharedFlow Basics
Unlike cold flow { }, SharedFlow is hot — active collectors share the same stream. replay=0 is typical for one-time events.
Emit and Collect
kotlin
import kotlinx.coroutines.*
import kotlinx.coroutines.flow.*
fun main() = runBlocking {
val events = MutableSharedFlow<String>()
val job = launch {
events.collect { println("Event: $it") }
}
delay(50)
events.emit("Signed in")
events.emit("Profile updated")
delay(50)
job.cancel()
}Output
Event: Signed in
Event: Profile updated
emit() sends events to active collectors. Late subscribers do not receive past events when replay is 0.
Dependency required:
implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.9.0")SharedFlow vs StateFlow
StateFlow always has a current value and replays the latest to new collectors. SharedFlow is better for navigation events, snackbars, and taps.
When to Use Which
kotlin
// StateFlow — UI state (always has current value)
// val uiState = MutableStateFlow(UiState())
// SharedFlow — one-time events (no initial value required)
// val snackbarEvents = MutableSharedFlow<String>()Output
No console output
This snippet shows the intent: StateFlow for state, SharedFlow for events that should not be replayed to new subscribers.
Best Practice: On Android, expose StateFlow for UI state and SharedFlow for one-off events like navigation.
Practice Exercise
Exercisemultiple choice
Which flow is best for a one-time "navigate to settings" event?
Quick Quiz
Quick Quiz
What makes SharedFlow "hot"?
Frequently Asked Questions
Related Tutorials
Last updated: 2026-05-19Kotlin 2.0
Written by KotlinGuide Editorial Team · Reviewed by KotlinGuide Technical Review