Compose Side Effects
UI › Compose Core
Running lifecycle-aware effects safely from side-effect-free composables in Jetpack Compose.
Side effects are a staple Compose interview topic because they probe whether you understand recomposition: composables run unpredictably, out of order, and may be discarded, so escaping that sandbox requires the right effect API. Interviewers test which effect to reach for, what the key parameter does on restart, and subtle traps like rememberUpdatedState versus restarting an effect.
What this covers
- Why composables must be pure: recomposition is frequent, reordered, and discardable, so direct side effects are unsafe
- LaunchedEffect: launches a composition-scoped coroutine, cancelled on leave, cancelled-and-restarted when a key changes
- DisposableEffect vs SideEffect: cleanup via onDispose versus publishing state to non-Compose code after each recomposition
- rememberCoroutineScope for launching coroutines from event handlers like onClick
- rememberUpdatedState to read the latest value inside a long-lived effect without restarting it
- produceState and snapshotFlow for bridging non-Compose sources into State and State into a Flow
Study this topic
- Compose Side Effects explained: the guided lesson
- 14 practice quiz questions
- 9 revision flashcards
- Compose Side Effects interview questions and answers