Android's InputManager::registerInputDeviceListener isn't calling my listener

Question

I'm trying to get a notification when input devices are added/removed, and from what I understand that's what registerInputDeviceListener should do... but my listener isn't being called!

Here's a snippet of my code:

InputManager im = (InputManager) getSystemService(Context.INPUT_SERVICE);
im.registerInputDeviceListener(new InputManager.InputDeviceListener() {
    @Override
    public void onInputDeviceAdded(int deviceId) {
        Log.d("Input", "InputDeviceAdded: " + deviceId);
    }

    @Override
    public void onInputDeviceRemoved(int deviceId) {
            Log.d("Input", "InputDeviceRemoved: " + deviceId);
    }

    @Override
    public void onInputDeviceChanged(int deviceId) {
        Log.d("Input", "InputDeviceChanged: " + deviceId);
    }
}, null);

And here's what I see in logcat when I unplug my usb mouse:

01-15 19:19:04.025: INFO/EventHub(5935): Removing device '/dev/input/event0' due to inotify event
01-15 19:19:04.025: INFO/EventHub(5935): Removed device: path=/dev/input/event0 name=Primax USB OPTICAL MOUSE id=11 fd=245 classes=0x80000008
01-15 19:19:04.045: INFO/InputReader(5935): Device removed: id=11, name='Primax USB OPTICAL MOUSE', sources=0x00002002

But my listener never gets called...

Answer 1

Turns out that the InputManager doesn't register itself for device changes unless getInputDevice or getInputDeviceByDescriptor is called previously.

Calling getInputDevice first (and ignoring the result) makes my callbacks get called.