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NullReferenceException in SFCombobox with bound ObservableCollection as ItemSource

Hi


we have an issue with the SFCombobox. On clearing or modifying the underlying ObservableCollection a NullReferenceException is thrown.

The issue is might be related to the issue of the ticket: https://www.syncfusion.com/forums/reply/148237

The problem occurs with Syncfusion 17.4.039 under Xamarin.Forms 4.4.0.991265

I assembled a demonstration project to reproduce this error.


Regards,


Alexander Köhler

Stacktrace:

System.NullReferenceException

  Message=Object reference not set to an instance of an object.


  at Syncfusion.Android.ComboBox.SfComboBox.Handle_CollectionChanged (System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x00000] in :0

  at (wrapper delegate-invoke) .invoke_void_object_NotifyCollectionChangedEventArgs(object,System.Collections.Specialized.NotifyCollectionChangedEventArgs)

  at System.Collections.ObjectModel.ObservableCollection`1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x00018] in /Users/builder/jenkins/workspace/archive-mono/2019-08/android/release/external/corefx/src/System.ObjectModel/src/System/Collections/ObjectModel/ObservableCollection.cs:263

  at System.Collections.ObjectModel.ObservableCollection`1[T].OnCollectionReset () [0x00000] in /Users/builder/jenkins/workspace/archive-mono/2019-08/android/release/external/corefx/src/System.ObjectModel/src/System/Collections/ObjectModel/ObservableCollection.cs:362

  at System.Collections.ObjectModel.ObservableCollection`1[T].ClearItems () [0x00018] in /Users/builder/jenkins/workspace/archive-mono/2019-08/android/release/external/corefx/src/System.ObjectModel/src/System/Collections/ObjectModel/ObservableCollection.cs:166

  at System.Collections.ObjectModel.Collection`1[T].Clear () [0x00014] in /Users/builder/jenkins/workspace/archive-mono/2019-08/android/release/external/corefx/src/Common/src/CoreLib/System/Collections/ObjectModel/Collection.cs:81

  at SyncFusionComboboxExample.TestViewModel.refillValues () [0x00001] in C:\SFCE\SyncFusionComboboxExample\SyncFusionComboboxExample\MainPage.xaml.cs:55

  at Xamarin.Forms.Command+<>c__DisplayClass4_0.<.ctor>b__0 (System.Object o) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Command.cs:74

  at Xamarin.Forms.Command.Execute (System.Object parameter) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Command.cs:112

  at Xamarin.Forms.ButtonElement.ElementClicked (Xamarin.Forms.VisualElement visualElement, Xamarin.Forms.Internals.IButtonElement ButtonElementManager) [0x00008] in D:\a\1\s\Xamarin.Forms.Core\ButtonElement.cs:60

  at Xamarin.Forms.Button.SendClicked () [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Button.cs:171

  at Xamarin.Forms.Platform.Android.ButtonElementManager.OnClick (Xamarin.Forms.VisualElement element, Xamarin.Forms.IButtonController buttonController, Android.Views.View v) [0x00000] in D:\a\1\s\Xamarin.Forms.Platform.Android\ButtonElementManager.cs:25

  at Xamarin.Forms.Platform.Android.FastRenderers.ButtonRenderer.Android.Views.View.IOnClickListener.OnClick (Android.Views.View v) [0x00000] in D:\a\1\s\Xamarin.Forms.Platform.Android\FastRenderers\ButtonRenderer.cs:71

  at Android.Views.View+IOnClickListenerInvoker.n_OnClick_Landroid_view_View_ (System.IntPtr jnienv, System.IntPtr native__this, System.IntPtr native_v) [0x00011] in <11f101b564894ca7af6c482ddc51c698>:0

  at (wrapper dynamic-method) Android.Runtime.DynamicMethodNameCounter.78(intptr,intptr,intptr)