# DownloadHelper.Callback

# DownloadHelper.Callback

Artifact:[androidx.media3:media3-exoplayer](https://developer.android.com/jetpack/androidx/releases/media3)  
[View Source](https://cs.android.com/search?q=file:androidx/media3/exoplayer/offline/DownloadHelper.java+class:androidx.media3.exoplayer.offline.DownloadHelper.Callback)

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Kotlin\|[Java](https://developer.android.com/reference/androidx/media3/exoplayer/offline/DownloadHelper.Callback "View this page in Java")

<br />

```
interface DownloadHelper.Callback
```

<br />

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A callback to be notified when the[DownloadHelper](https://developer.android.com/reference/kotlin/androidx/media3/exoplayer/offline/DownloadHelper)is prepared.

## Summary

|                             ### Public functions                              |
|-------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onPrepareError](https://developer.android.com/reference/kotlin/androidx/media3/exoplayer/offline/DownloadHelper.Callback#onPrepareError(androidx.media3.exoplayer.offline.DownloadHelper,java.io.IOException))`(helper: `[DownloadHelper](https://developer.android.com/reference/kotlin/androidx/media3/exoplayer/offline/DownloadHelper)`!, e: `[IOException](https://developer.android.com/reference/java/io/IOException.html)`!)` Called when preparation fails.      |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onPrepared](https://developer.android.com/reference/kotlin/androidx/media3/exoplayer/offline/DownloadHelper.Callback#onPrepared(androidx.media3.exoplayer.offline.DownloadHelper,boolean))`(helper: `[DownloadHelper](https://developer.android.com/reference/kotlin/androidx/media3/exoplayer/offline/DownloadHelper)`!, tracksInfoAvailable: `[Boolean](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html)`)` Called when preparation completes. |

## Public functions

### onPrepareError

```
fun onPrepareError(helper: DownloadHelper!, e: IOException!): Unit
```

Called when preparation fails.  

|                                                           Parameters                                                           |
|--------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------|
| `helper: `[DownloadHelper](https://developer.android.com/reference/kotlin/androidx/media3/exoplayer/offline/DownloadHelper)`!` | The reporting[DownloadHelper](https://developer.android.com/reference/kotlin/androidx/media3/exoplayer/offline/DownloadHelper). |
| `e: `[IOException](https://developer.android.com/reference/java/io/IOException.html)`!`                                        | The error.                                                                                                                      |

### onPrepared

```
fun onPrepared(helper: DownloadHelper!, tracksInfoAvailable: Boolean): Unit
```

Called when preparation completes.  

|                                                           Parameters                                                           |
|--------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------|
| `helper: `[DownloadHelper](https://developer.android.com/reference/kotlin/androidx/media3/exoplayer/offline/DownloadHelper)`!` | The reporting[DownloadHelper](https://developer.android.com/reference/kotlin/androidx/media3/exoplayer/offline/DownloadHelper). |
| `tracksInfoAvailable: `[Boolean](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html)                     | Whether tracks information is available.                                                                                        |