Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

# BrailleDisplayController.BrailleDisplayCallback

*** ** * ** ***

` public static interface BrailleDisplayController.BrailleDisplayCallback `   
` `

|---|
| android.accessibilityservice.BrailleDisplayController.BrailleDisplayCallback |

<br />

*** ** * ** ***

Interface provided to `https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController` connection methods to receive callbacks from the system.

## Summary

| ### Constants ||
|---|---|
| `int` | `https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController.BrailleDisplayCallback#FLAG_ERROR_BRAILLE_DISPLAY_NOT_FOUND` A unique Braille display matching the requested properties could not be identified. |
| `int` | `https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController.BrailleDisplayCallback#FLAG_ERROR_CANNOT_ACCESS` The system cannot access connected HID devices. |

| ### Public methods ||
|---|---|
| ` abstract void` | ` https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController.BrailleDisplayCallback#onConnected(byte[])(byte[] hidDescriptor) ` Callback to observe a successful Braille display connection. |
| ` abstract void` | ` https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController.BrailleDisplayCallback#onConnectionFailed(int)(int errorFlags) ` Callback to observe a failed Braille display connection. |
| ` abstract void` | ` https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController.BrailleDisplayCallback#onDisconnected()() ` Callback to observe when the currently connected Braille display is disconnected by the system. |
| ` abstract void` | ` https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController.BrailleDisplayCallback#onInput(byte[])(byte[] input) ` Callback to observe input bytes from the currently connected Braille display. |

## Constants

### FLAG_ERROR_BRAILLE_DISPLAY_NOT_FOUND

Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public static final int FLAG_ERROR_BRAILLE_DISPLAY_NOT_FOUND
```

A unique Braille display matching the requested properties could not be identified.

<br />

Constant Value: 2 (0x00000002)

### FLAG_ERROR_CANNOT_ACCESS

Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public static final int FLAG_ERROR_CANNOT_ACCESS
```

The system cannot access connected HID devices.

<br />

Constant Value: 1 (0x00000001)

## Public methods

### onConnected

Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract void onConnected (byte[] hidDescriptor)
```

Callback to observe a successful Braille display connection.

The provided HID report descriptor should be used to understand the input bytes received from the Braille display via `https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController.BrailleDisplayCallback#onInput(byte[])` and to prepare the output sent to the Braille display via `https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController#write(byte[])`.

<br />

| Parameters ||
|---|---|
| `hidDescriptor` | `byte`: The HID report descriptor for this Braille display. This value cannot be `null`. <br /> |

**See also:**

- `https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController#connect(android.bluetooth.BluetoothDevice,%20android.accessibilityservice.BrailleDisplayController.BrailleDisplayCallback)`
- `https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController#connect(android.hardware.usb.UsbDevice,%20android.accessibilityservice.BrailleDisplayController.BrailleDisplayCallback)`

### onConnectionFailed

Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract void onConnectionFailed (int errorFlags)
```

Callback to observe a failed Braille display connection.

<br />

| Parameters ||
|---|---|
| `errorFlags` | `int`: A bitmask of error codes for the connection failure. Value is either `0` or a combination of the following: - `https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController.BrailleDisplayCallback#FLAG_ERROR_CANNOT_ACCESS` - `https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController.BrailleDisplayCallback#FLAG_ERROR_BRAILLE_DISPLAY_NOT_FOUND` |

**See also:**

- `https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController#connect(android.bluetooth.BluetoothDevice,%20android.accessibilityservice.BrailleDisplayController.BrailleDisplayCallback)`
- `https://developer.android.com/reference/android/accessibilityservice/BrailleDisplayController#connect(android.hardware.usb.UsbDevice,%20android.accessibilityservice.BrailleDisplayController.BrailleDisplayCallback)`

### onDisconnected

Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract void onDisconnected ()
```

Callback to observe when the currently connected Braille display is disconnected by the system.

<br />

### onInput

Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract void onInput (byte[] input)
```

Callback to observe input bytes from the currently connected Braille display.

<br />

| Parameters ||
|---|---|
| `input` | `byte`: The input bytes from the Braille display, formatted according to the HID report descriptor and the HIDRAW kernel driver. This value cannot be `null`. <br /> |