ClassNotFoundException when inflating a binding library using Xamarin

Question

I have made a custom binding for the twoway-view library.

The DLL generate seems to okay, I can do the following without any problem:

var twoWayView = new Org.Lucasr.TwoWayView.Widget.TwoWayView(this);

however if a try to instantiate the class using java reflection:

Java.Lang.Class.ForName("Org.Lucasr.TwoWayView.Widget.TwoWayView")

I got an ClassNotFoundException, which it the same exception that occur when trying to inflate a layout that have TwoWayView in it like this one:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <Button
        android:id="@+id/MyButton"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/Hello" />
    <Org.Lucasr.Twowayview.Widget.TwoWayView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:scrollbars="vertical"
        app:twowayview_layoutManager="StaggeredGridLayoutManager"
        app:twowayview_numColumns="2"
        app:twowayview_numRows="1" />
</LinearLayout>

---

Edit

Using dexdump as described here I can see the class is inside my apk:

Class #1172            -
  Class descriptor  : 'Lorg/lucasr/twowayview/widget/TwoWayView;'
  Access flags      : 0x0001 (PUBLIC)
  Superclass        : 'Landroid/support/v7/widget/RecyclerView;'
  Interfaces        -

Edit 2

Using org.lucasr.twowayview.widget.TwoWayView give me the same error.

The complete Exception is:

01-23 13:02:04.837 I/MonoDroid(17779): UNHANDLED EXCEPTION: 
01-23 13:02:04.861 I/MonoDroid(17779): Android.Views.InflateException: Exception of type 'Android.Views.InflateException' was thrown. 
01-23 13:02:04.861 I/MonoDroid(17779): at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () <IL 0x00011, 0x00068> 
01-23 13:02:04.861 I/MonoDroid(17779): at Android.Runtime.JNIEnv.CallNonvirtualVoidMethod (intptr,intptr,intptr,Android.Runtime.JValue[]) [0x00084] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.21-series/49a04b96/source/monodroid/src/Mono.Android/src/Runtime/JNIEnv.g.cs:896 
01-23 13:02:04.861 I/MonoDroid(17779): at Android.App.Activity.SetContentView (int) [0x00070] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.21-series/49a04b96/source/monodroid/src/Mono.Android/platforms/android-19/src/generated/Android.App.Activity.cs:4253 
01-23 13:02:04.861 I/MonoDroid(17779): at Org.Lucasr.TwoWayView.Sample.MainActivity.OnCreate (Android.OS.Bundle) [0x0001d] in c:\Users\guilherme\Documents\Visual Studio 2013\Projects\Org.Lucasr.TwoWayView\Org.Lucasr.TwoWayView.Sample\MainActivity.cs:25 
01-23 13:02:04.862 I/MonoDroid(17779): at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (intptr,intptr,intptr) [0x00011] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.21-series/49a04b96/source/monodroid/src/Mono.Android/platforms/android-19/src/generated/Android.App.Activity.cs:2179 
01-23 13:02:04.862 I/MonoDroid(17779): at (wrapper dynamic-method) object.e4603f87-2e86-4a8a-9cd2-213f87378350 (intptr,intptr,intptr) <IL 0x00017, 0x00043> 
01-23 13:02:04.862 I/MonoDroid(17779):   --- End of managed exception stack trace --- 
01-23 13:02:04.862 I/MonoDroid(17779): android.view.InflateException: Binary XML file line #1: Error inflating class Org.Lucasr.Twowayview.Widget.TwoWayView 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:757) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.view.LayoutInflater.rInflate(LayoutInflater.java:806) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.view.LayoutInflater.inflate(LayoutInflater.java:504) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
01-23 13:02:04.862 I/MonoDroid(17779):  at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:377) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.app.Activity.setContentView(Activity.java:2144) 
01-23 13:02:04.862 I/MonoDroid(17779):  at org.lucasr.twowayview.sample.MainActivity.n_onCreate(Native Method) 
01-23 13:02:04.862 I/MonoDroid(17779):  at org.lucasr.twowayview.sample.MainActivity.onCreate(MainActivity.java:28) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.app.Activity.performCreate(Activity.java:5933) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.app.ActivityThread.access$800(ActivityThread.java:144) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.os.Handler.dispatchMessage(Handler.java:102) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.os.Looper.loop(Looper.java:135) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.app.ActivityThread.main(ActivityThread.java:5221) 
01-23 13:02:04.862 I/MonoDroid(17779):  at java.lang.reflect.Method.invoke(Native Method) 
01-23 13:02:04.862 I/MonoDroid(17779):  at java.lang.reflect.Method.invoke(Method.java:372) 
01-23 13:02:04.862 I/MonoDroid(17779):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
01-23 13:02:04.862 I/MonoDroid(17779):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
01-23 13:02:04.862 I/MonoDroid(17779): Caused by: java.lang.ClassNotFoundException: Didn't find class "Org.Lucasr.Twowayview.Widget.TwoWayView" on path: DexPathList[[zip file "/data/app/Org.Lucasr.TwoWayView.Sample-1/base.apk"],nativeLibraryDirectories=[/data/app/Org.Lucasr.TwoWayView.Sample-1/lib/arm, /vendor/lib, /system/lib]] 
01-23 13:02:04.862 I/MonoDroid(17779):  at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56) 
01-23 13:02:04.862 I/MonoDroid(17779):  at java.lang.ClassLoader.loadClass(ClassLoader.java:511) 
01-23 13:02:04.862 I/MonoDroid(17779):  at java.lang.ClassLoader.loadClass(ClassLoader.java:469) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.view.LayoutInflater.createView(LayoutInflater.java:571) 
01-23 13:02:04.862 I/MonoDroid(17779):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743) 
01-23 13:02:04.862 I/MonoDroid(17779):  ... 21 more 
01-23 13:02:04.862 I/MonoDroid(17779):  Suppressed: java.lang.ClassNotFoundException: Org.Lucasr.Twowayview.Widget.TwoWayView 
01-23 13:02:04.862 I/MonoDroid(17779):      at java.lang.Class.classForName(Native Method) 
01-23 13:02:04.862 I/MonoDroid(17779):      at java.lang.BootClassLoader.findClass(ClassLoader.java:781) 
01-23 13:02:04.863 I/MonoDroid(17779):      at java.lang.BootClassLoader.loadClass(ClassLoader.java:841) 
01-23 13:02:04.863 I/MonoDroid(17779):      at java.lang.ClassLoader.loadClass(ClassLoader.java:504) 
01-23 13:02:04.863 I/MonoDroid(17779):      ... 24 more 
01-23 13:02:04.863 I/MonoDroid(17779):  Caused by: java.lang.NoClassDefFoundError: Class not found using the boot class loader; no stack available An unhandled exception occured.  
01-23 13:02:05.453 E/mono    (17779):  
01-23 13:02:05.453 E/mono    (17779): Unhandled Exception: 
01-23 13:02:05.453 E/mono    (17779): Android.Views.InflateException: Exception of type 'Android.Views.InflateException' was thrown. 
01-23 13:02:05.453 E/mono (17779): at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () <IL 0x00011, 0x00068> 
01-23 13:02:05.453 E/mono    (17779): at Android.Runtime.JNIEnv.CallNonvirtualVoidMethod (intptr,intptr,intptr,Android.Runtime.JValue[]) [0x00084] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.21-series/49a04b96/source/monodroid/src/Mono.Android/src/Runtime/JNIEnv.g.cs:896 
01-23 13:02:05.453 E/mono    (17779): at Android.App.Activity.SetContentView (int) [0x00070] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.21-series/49a04b96/source/monodroid/src/Mono.Android/platforms/android-19/src/generated/Android.App.Activity.cs:4253 
01-23 13:02:05.453 E/mono    (17779): at Org.Lucasr.TwoWayView.Sample.MainActivity.OnCreate (Android.OS.Bundle) [0x0001d] in c:\Users\guilherme\Documents\Visual Studio 2013\Projects\Org.Lucasr.TwoWayView\Org.Lucasr.TwoWayView.Sample\MainActivity.cs:25 
01-23 13:02:05.453 E/mono    (17779): at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (intptr,intptr,intptr) [0x00011] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.21-series/49a04b96/source/monodroid/src/Mono.Android/platforms/android-19/src/generated/Android.App.Activity.cs:2179 
01-23 13:02:05.453 E/mono    (17779): at (wrapper dynamic-method) object.e4603f87-2e86-4a8a-9cd2-213f87378350 (intptr,intptr,intptr) <IL 0x00017, 0x00043> 
01-23 13:02:05.453 E/mono    (17779):  
01-23 13:02:05.453 E/mono    (17779):   --- End of managed exception stack trace --- 
01-23 13:02:05.453 E/mono    (17779): android.view.InflateException: Binary XML file line #1: Error inflating class Org.Lucasr.Twowayview.Widget.TwoWayView 
01-23 13:02:05.453 E/mono    (17779):   at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:757) 
01-23 13:02:05.453 E/mono    (17779):   at android.view.LayoutInflater.inflate(LayoutInflater.java:504) 
01-23 13:02:05.453 E/mono    (17779):   at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
01-23 13:02:05.453 E/mono    (17779):   at android.view.LayoutInflater.inflate(LayoutInflater.java:365) referenceTable GDEF length=670 1 referenceTable GSUB length=7202 1 referenceTable GPOS length=24560 1 
01-23 13:02:05.453 E/mono    (17779):   at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:377) 
01-23 13:02:05.453 E/mono    (17779):   at android.app.Activity.setContentView(Activity.java:2144) 
01-23 13:02:05.453 E/mono    (17779):   at org.lucasr.twowayview.sample.MainActivity.n_onCreate(Native Method) 
01-23 13:02:05.453 E/mono    (17779):   at org.lucasr.twowayview.sample.MainActivity.onCreate(MainActivity.java:28) 
01-23 13:02:05.453 E/mono    (17779):   at android.app.Activity.performCreate(Activity.java:5933) 
01-23 13:02:05.453 E/mono    (17779):   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) 
01-23 13:02:05.453 E/mono    (17779):   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251) 
01-23 13:02:05.453 E/mono    (17779):   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
01-23 13:02:05.453 E/mono    (17779):   at android.app.ActivityThread.access$800(ActivityThread.java:144) 
01-23 13:02:05.453 E/mono    (17779):   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
01-23 13:02:05.453 E/mono    (17779):   at android.os.Handler.dispatchMessage(Handler.java:102) 
01-23 13:02:05.453 E/mono    (17779):   at android.os.Looper.loop(Looper.java:135) 
01-23 13:02:05.453 E/mono    (17779):   at android.app.ActivityThread.main(ActivityThread.java:5221) 
01-23 13:02:05.453 E/mono    (17779):   at java.lang.reflect.Method.invoke(Native Method)

Answer 1

This sound similar to an issue I had when trying to dynamically create objects using reflection. In my case, it was the Xamarin Linker that removed the class when building.

You can read more about the linker here: https://developer.xamarin.com/guides/android/advanced_topics/linking/

Try setting it to "Don't link", to see if that removes the error. If so, you need to reference the class statically or mark it as Preserve.