Execution Order in Jetpack Compose Explained with Analogies
28 Jan 2025Understanding when LaunchedEffect, DisposableEffect, and composables run in Jetpack Compose can be tricky. Let’s simplify with a few real-world analogies.
🎭 Composables = Stage Actors
Composables are like actors:
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They enter when the screen appears.
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They update their lines when state changes (recomposition).
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They exit when removed from the UI.
🕯️ LaunchedEffect = Candle in a Room
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You light a candle when entering a room →
LaunchedEffectruns. -
If the room changes (key changes), you blow it out and light a new one.
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If you leave, the candle is blown out.
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Use it for one-time effects or state collection.
🧹 DisposableEffect = Hotel Housekeeping
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Housekeeper sets up the room →
DisposableEffectruns. -
When you check out (or key changes), the room is cleaned → onDispose is called.
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Perfect for listeners or subscriptions that need cleanup.
🔄 Recomposition = Changing Actor’s Lines
If the script (state) changes, actors stay on stage but adjust their lines. No need to re-run effects unless keys change.
Quick Comparison
| Concept | Analogy | When It Runs | When It Cleans Up |
|---|---|---|---|
| Composable | Actor | On screen draw/state | On removal |
| LaunchedEffect | Candle | On enter/key change | On key change/removal |
| DisposableEffect | Housekeeping | On enter/key change | On key change/removal |
✅ Final Tip
So next time you add a LaunchedEffect or a DisposableEffect, ask yourself:
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Is this a one-time action? → Use
LaunchedEffect. -
Does it need cleanup? → Use
DisposableEffect. -
Thinking this way makes Compose easier and your code cleaner.
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Side-Effect official docs.
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LaunchedEffect official docs.