# OnBackCompletedFallback

Artifact: [androidx.navigationevent:navigationevent](https://developer.android.com/jetpack/androidx/releases/navigationevent) [View Source](https://cs.android.com/search?q=file:androidx/navigationevent/OnBackCompletedFallback.kt+class:androidx.navigationevent.OnBackCompletedFallback) Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/navigationevent#1.0.0)

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Common/AllAndroid/JVMJavaScript
- Cmn

  ```
  fun interface OnBackCompletedFallback
  ```

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A listener that provides a final fallback action for unhandled `backCompleted` callbacks.

This is typically used to provide a default system behavior, like finishing an `Activity`, when no other part of the application consumes the back navigation event.

## Summary

| ### Public functions |
|---|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/navigationevent/OnBackCompletedFallback#onBackCompletedFallback()()` Called when a `backCompleted` callback is dispatched but not handled by any `https://developer.android.com/reference/kotlin/androidx/navigationevent/NavigationEventHandler`. | Cmn |

## Public functions

### onBackCompletedFallback

Cmn Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/navigationevent#1.0.0)

```
fun onBackCompletedFallback(): Unit
```

Called when a `backCompleted` callback is dispatched but not handled by any `https://developer.android.com/reference/kotlin/androidx/navigationevent/NavigationEventHandler`.