API reference

DeviceSelector Interface

Interface for selecting which device should be used for SDK operations.
Device selectors determine which connected device should receive commands or stream data, enabling flexible device targeting strategies. Implementations can select devices automatically based on connectivity, target a specific device by identifier, or implement custom selection logic.
The SDK provides two built-in implementations:
  • AutoDeviceSelector: Automatically selects an optimal connected, compatible device and switches to another when the current device disconnects or becomes incompatible.
  • SpecificDeviceSelector: Targets a specific device by its identifier, emitting null when that device is not present without falling back to other devices.
Example: 
// Auto-select the best connected device
val autoSelector = AutoDeviceSelector()
val session = Wearables.createSession(autoSelector)
// Target a specific device
val deviceId = Wearables.devices.value.first()
val specificSelector = SpecificDeviceSelector(deviceId)
val session = Wearables.createSession(specificSelector)

See Also

Signature

interface DeviceSelector

Methods

activeDevice ()
Returns the currently selected device identifier, or null if no device is selected.
This provides synchronous access to the latest selected device. The value is eagerly cached from the underlying device selection flow, so it always reflects the most recent state without requiring flow collection.
Signature 
abstract fun activeDevice(): DeviceIdentifier?
Returns
DeviceIdentifier?  The DeviceIdentifier of the currently selected device, or null if no suitable device is available
activeDeviceFlow ()
Returns a Flow that emits the currently selected device identifier, or null when no device is selected.
Use this to reactively observe device selection changes. The flow emits whenever the selected device changes — for example, when a device connects, disconnects, or when the selector switches to a different device.
Signature 
abstract fun activeDeviceFlow(): Flow<DeviceIdentifier?>
Returns
Flow<DeviceIdentifier?>  A Flow of DeviceIdentifier representing the active device, or null when no suitable device is available