Is there any way to get information about a hardware keyboard connected to an Android device?

Question

I've looked everywhere but can't find an answer specifically for hardware keyboards.

I've tried checking the devices list from UsbManager but it comes up empty.

I am able to detect whether a hardware keyboard is detected or when it is connected/disconnected but I am not sure if it's possible to extract information about the device (serial number, name, etc.).

Is this even possible?

Answer 1

I ended up using the InputManager to get the information I needed.

In onCreate I would call a method to go over all the InputDevices and filter out the non-external, non-keyboard devices:

private fun checkForPhysicalKeyboards() =
    viewModel.setPhysicalKeyboardDevices(inputManager.inputDeviceIds.toTypedArray()
        .mapNotNull { inputManager.getInputDevice(it) }.filter { it.isExternalKeyboard() })

private fun InputDevice.isExternalKeyboard() =
    isExternal && keyboardType == InputDevice.KEYBOARD_TYPE_ALPHABETIC

I then also registered an InputDeviceListener with the InputManager to monitor for changes as not every connection/disconnection of a keyboard would count as a configuration change that would cause the activity to be recreated:

private val inputDeviceListener = object : InputManager.InputDeviceListener {
    override fun onInputDeviceAdded(deviceId: Int) {
        inputManager.getInputDevice(deviceId)?.takeIf { it.isExternalKeyboard() }
            ?.let { viewModel.addPhysicalKeyboardDevice(it) }
    }

    override fun onInputDeviceRemoved(deviceId: Int) =
        viewModel.removePhysicalKeyboardDevice(deviceId)

    override fun onInputDeviceChanged(deviceId: Int) {
        inputManager.getInputDevice(deviceId)
            ?.let { viewModel.updatePhysicalKeyboardDevice(it) }
    }
}

The InputDevice objects contained all the information I needed from the connected devices.