# ObserverCallback

Artifact: [androidx.appsearch:appsearch](https://developer.android.com/jetpack/androidx/releases/appsearch) [View Source](https://cs.android.com/search?q=file:androidx/appsearch/observer/ObserverCallback.java+class:androidx.appsearch.observer.ObserverCallback) Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/appsearch#1.1.0)

*** ** * ** ***


```
public interface ObserverCallback
```

<br />

*** ** * ** ***

An interface which apps can implement to subscribe to notifications of changes to AppSearch data.

## Summary

| ### Public methods |
|---|---|
| `abstract void` | `https://developer.android.com/reference/androidx/appsearch/observer/ObserverCallback#onDocumentChanged(androidx.appsearch.observer.DocumentChangeInfo)(@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/androidx/appsearch/observer/DocumentChangeInfo changeInfo)` Callback to trigger after document changes (documents added, updated or removed). |
| `abstract void` | `https://developer.android.com/reference/androidx/appsearch/observer/ObserverCallback#onSchemaChanged(androidx.appsearch.observer.SchemaChangeInfo)(@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/androidx/appsearch/observer/SchemaChangeInfo changeInfo)` Callback to trigger after schema changes (schema type added, updated or removed). |

## Public methods

### onDocumentChanged

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/appsearch#1.1.0)

```
abstract void onDocumentChanged(@NonNull DocumentChangeInfo changeInfo)
```

Callback to trigger after document changes (documents added, updated or removed).

| Parameters |
|---|---|
| `@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/androidx/appsearch/observer/DocumentChangeInfo changeInfo` | Information about the nature of the change. |

### onSchemaChanged

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/appsearch#1.1.0)

```
abstract void onSchemaChanged(@NonNull SchemaChangeInfo changeInfo)
```

Callback to trigger after schema changes (schema type added, updated or removed).

| Parameters |
|---|---|
| `@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/androidx/appsearch/observer/SchemaChangeInfo changeInfo` | Information about the nature of the change. |