Bug 10010 - Calling inputManager.RegisterInputDeviceListener always gives "listener must not be null" error
Summary: Calling inputManager.RegisterInputDeviceListener always gives "listener must ...
Alias: None
Product: Android
Classification: Xamarin
Component: BCL Class Libraries ()
Version: 4.4.x
Hardware: PC Windows
: Normal normal
Target Milestone: ---
Assignee: Atsushi Eno
Depends on:
Reported: 2013-02-04 05:21 UTC by David Leaver
Modified: 2013-06-24 12:03 UTC (History)
4 users (show)

Is this bug a regression?: ---
Last known good build:

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Description David Leaver 2013-02-04 05:21:10 UTC
Calling inputManager.RegisterInputDeviceListener always fails with the error:

Unhandled Exception:
Java.Lang.IllegalArgumentException: listener must not be null

Which makes me think the binding is screwed up, as the error should only come up if you pass null and I'm definitely not.

Example code follows, just call InputDeviceListener.Init(context);

internal class InputDeviceListener : InputManager.IInputDeviceListener
	public static void Init(Context context)
		var inputManager = (InputManager)context.GetSystemService("input");

		inputManager.RegisterInputDeviceListener(new InputDeviceListener(), null);

	public void Dispose()

	public IntPtr Handle { get; private set; }
	public void OnInputDeviceAdded(int deviceId)
		var device = InputDevice.GetDevice(deviceId);

	public void OnInputDeviceChanged(int deviceId)

	public void OnInputDeviceRemoved(int deviceId)

My test device is an OUYA console, which is running Android 4.1.2.
Thanks guys :-)
Comment 1 David Leaver 2013-02-04 05:26:11 UTC
Related bug on the MonoGame project:
Comment 2 Atsushi Eno 2013-06-21 05:37:12 UTC
I couldn't reproduce this issue. I don't have OUYA so I tried only on my JellyBean emulator though. I'm asking some other people to try.

AOSP is not always fully used, so there might be still some difference in the code running on your device.
Comment 4 Jonathan Pryor 2013-06-24 12:03:23 UTC
You MUST NOT implement IJavaObject yourself.

> by inheriting from Java.Lang.Object.

IJavaObject.Handle is a reference to the Java-VM object. InputDeviceListener never sets it, and thus it will always be IntPtr.Zero, i.e. `null`, which is why InputManager.RegisterInputDeviceListener() throws an IllegalArgumentException.