# AccessibilityButtonController.AccessibilityButtonCallback

Added in[API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)

# AccessibilityButtonCallback

*** ** * ** ***

Kotlin\|[Java](https://developer.android.com/reference/android/accessibilityservice/AccessibilityButtonController.AccessibilityButtonCallback "View this page in Java")  

```
abstract class AccessibilityButtonCallback
```

|---|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [kotlin.Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html)                                                                                                                                                   ||
| ↳ | [android.accessibilityservice.AccessibilityButtonController.AccessibilityButtonCallback](https://developer.android.com/reference/kotlin/android/accessibilityservice/AccessibilityButtonController.AccessibilityButtonCallback#) |

Callback for interaction with and changes to state of the accessibility button within the system's navigation area.

## Summary

|                                                                                               Public constructors                                                                                                ||
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---|
| [AccessibilityButtonCallback](https://developer.android.com/reference/kotlin/android/accessibilityservice/AccessibilityButtonController.AccessibilityButtonCallback#AccessibilityButtonCallback())`()` <br /> |

|                                                                                                                                                                                                                                                                                                                                                        Public methods                                                                                                                                                                                                                                                                                                                                                        ||
|----------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| open[Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [onAvailabilityChanged](https://developer.android.com/reference/kotlin/android/accessibilityservice/AccessibilityButtonController.AccessibilityButtonCallback#onAvailabilityChanged(android.accessibilityservice.AccessibilityButtonController,%20kotlin.Boolean))`(`controller:` `[AccessibilityButtonController](https://developer.android.com/reference/kotlin/android/accessibilityservice/AccessibilityButtonController)!`, `available:` `[Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html)`)` Called when the availability of the accessibility button in the system's navigation area has changed. |
| open[Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [onClicked](https://developer.android.com/reference/kotlin/android/accessibilityservice/AccessibilityButtonController.AccessibilityButtonCallback#onClicked(android.accessibilityservice.AccessibilityButtonController))`(`controller:` `[AccessibilityButtonController](https://developer.android.com/reference/kotlin/android/accessibilityservice/AccessibilityButtonController)!`)` Called when the accessibility button in the system's navigation area is clicked.                                                                                                                                                                   |

## Public constructors

### AccessibilityButtonCallback

```
AccessibilityButtonCallback()
```

## Public methods

### onAvailabilityChanged

Added in[API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)  

```
open fun onAvailabilityChanged(
    controller: AccessibilityButtonController!, 
    available: Boolean
): Unit
```

Called when the availability of the accessibility button in the system's navigation area has changed. The accessibility button may become unavailable because the device shopped showing the button, the button was assigned to another service, or for other reasons.

|                                                                                                 Parameters                                                                                                  ||
|--------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `controller` | [AccessibilityButtonController](https://developer.android.com/reference/kotlin/android/accessibilityservice/AccessibilityButtonController)!:the controller used to register for this callback |
| `available`  | [Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html):`true`if the accessibility button is available to this service,`false`otherwise                            |

### onClicked

Added in[API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)  

```
open fun onClicked(controller: AccessibilityButtonController!): Unit
```

Called when the accessibility button in the system's navigation area is clicked.

|                                                                                                 Parameters                                                                                                  ||
|--------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `controller` | [AccessibilityButtonController](https://developer.android.com/reference/kotlin/android/accessibilityservice/AccessibilityButtonController)!:the controller used to register for this callback |