multi-camera-api-2.kt

fun openDualCamera(cameraManager: CameraManager,
                   dualCamera: DualCamera,
                   executor: Executor = AsyncTask.SERIAL_EXECUTOR,
                   callback: (CameraDevice) -> Unit) {

    cameraManager.openCamera(
            dualCamera.logicalId, executor, object : CameraDevice.StateCallback() {
        override fun onOpened(device: CameraDevice) = callback(device)
        // Omitting for brevity...
        override fun onError(device: CameraDevice, error: Int) = onDisconnected(device)
        override fun onDisconnected(device: CameraDevice) = device.close()
    })
}