# LifecycleEventObserver

Artifact: [androidx.lifecycle:lifecycle-common](https://developer.android.com/jetpack/androidx/releases/lifecycle) [View Source](https://cs.android.com/search?q=file:androidx/lifecycle/LifecycleEventObserver.kt+class:androidx.lifecycle.LifecycleEventObserver) Added in [2.1.0](https://developer.android.com/jetpack/androidx/releases/lifecycle#2.1.0)

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Common/AllAndroid/JVM
- Cmn

  ```
  fun interface LifecycleEventObserver : LifecycleObserver
  ```

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Interface for receiving any `https://developer.android.com/reference/kotlin/androidx/lifecycle/Lifecycle.Event` state changes.

If a class implements both this interface and `https://developer.android.com/reference/kotlin/androidx/lifecycle/DefaultLifecycleObserver`, the methods of `https://developer.android.com/reference/kotlin/androidx/lifecycle/DefaultLifecycleObserver` are called first, followed by `https://developer.android.com/reference/kotlin/androidx/lifecycle/LifecycleEventObserver#onStateChanged(androidx.lifecycle.LifecycleOwner,androidx.lifecycle.Lifecycle.Event)`.

**Note:** If a class implements this interface and also uses the deprecated `androidx.lifecycle.OnLifecycleEvent` annotations, those annotations are ignored.

## Summary

| ### Public functions |
|---|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/lifecycle/LifecycleEventObserver#onStateChanged(androidx.lifecycle.LifecycleOwner,androidx.lifecycle.Lifecycle.Event)(source: https://developer.android.com/reference/kotlin/androidx/lifecycle/LifecycleOwner, event: https://developer.android.com/reference/kotlin/androidx/lifecycle/Lifecycle.Event)` Called when a state transition `https://developer.android.com/reference/kotlin/androidx/lifecycle/LifecycleEventObserver#onStateChanged(androidx.lifecycle.LifecycleOwner,androidx.lifecycle.Lifecycle.Event)` occurs. | Cmn |

## Public functions

### onStateChanged

Cmn Added in [2.1.0](https://developer.android.com/jetpack/androidx/releases/lifecycle#2.1.0)

```
fun onStateChanged(source: LifecycleOwner, event: Lifecycle.Event): Unit
```

Called when a state transition `https://developer.android.com/reference/kotlin/androidx/lifecycle/LifecycleEventObserver#onStateChanged(androidx.lifecycle.LifecycleOwner,androidx.lifecycle.Lifecycle.Event)` occurs.