Bug 22191 - On Android, NavigationPage.PushAsync() with Switch produces NullReferenceException
Summary: On Android, NavigationPage.PushAsync() with Switch produces NullReferenceExce...
Status: RESOLVED FIXED
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 1.2.2
Hardware: PC All
: Normal normal
Target Milestone: ---
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2014-08-19 02:12 UTC by Brendan Zagaeski (Xamarin Team, assistant)
Modified: 2014-12-04 07:50 UTC (History)
6 users (show)

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


Attachments
Test case (89.93 KB, application/zip)
2014-08-19 02:12 UTC, Brendan Zagaeski (Xamarin Team, assistant)
Details


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Status:
RESOLVED FIXED

Description Brendan Zagaeski (Xamarin Team, assistant) 2014-08-19 02:12:13 UTC
Created attachment 7717 [details]
Test case

On Android, NavigationPage.PushAsync() with Switch on second page produces NullReferenceException after leaving and returning to the second page.


## Steps to reproduce

1. Run the FormsApp1.Android project from the attached test case on device or emulator.

2. Tap the full-screen "Go To Page 2" button.

3. Tap the back navigation button (the Android icon) in the top left corner of the screen.

4. Tap the full-screen "Go To Page 2" button again.

5. Tap the Switch widget.



## Result with Xamarin.Forms 1.2.2.6243

> UNHANDLED EXCEPTION:
> System.NullReferenceException: Object reference not set to an instance of an object
>  at Xamarin.Forms.Platform.Android.SwitchRenderer.HandleToggled (object,System.EventArgs) <IL 0x0000c, 0x00084>
>  at (wrapper delegate-invoke) System.EventHandler`1<Xamarin.Forms.ToggledEventArgs>.invoke_void_object_TEventArgs (object,Xamarin.Forms.ToggledEventArgs) <0x0009f>
>  at (wrapper delegate-invoke) System.EventHandler`1<Xamarin.Forms.ToggledEventArgs>.invoke_void_object_TEventArgs (object,Xamarin.Forms.ToggledEventArgs) <0x00067>
>  at Xamarin.Forms.Switch.<.cctor>b__0 (Xamarin.Forms.BindableObject,object,object) <IL 0x0001c, 0x00123>
>  at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty,object,bool,bool,bool) <IL 0x000b9, 0x0058f>
>  at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty,object,bool,bool,bool) <IL 0x00213, 0x00aa3>
>  at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty,object,bool) <IL 0x0005a, 0x00277>
>  at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty,object) <IL 0x00004, 0x00057>
>  at Xamarin.Forms.Switch.set_IsToggled (bool) <IL 0x0000c, 0x00083>
>  at Xamarin.Forms.Platform.Android.SwitchRenderer.Android.Widget.CompoundButton.IOnCheckedChangeListener.OnCheckedChanged (Android.Widget.CompoundButton,bool) <IL 0x00007, 0x00073>
>  at Android.Widget.CompoundButton/IOnCheckedChangeListenerInvoker.n_OnCheckedChanged_Landroid_widget_CompoundButton_Z (intptr,intptr,intptr,bool) [0x00011] in /Users/builder/data/lanes/1131/dc424d15/source/monodroid/src/Mono.Android/platforms/android-19/src/generated/Android.Widget.CompoundButton.cs:76
>  at (wrapper dynamic-method) object.f855b3dc-a845-41ed-b3ca-8c6ce2dbb337 (intptr,intptr,intptr,bool) <IL 0x0001d, 0x0004b>
> Could not find method java.lang.Throwable.<init>, referenced from method android.runtime.JavaProxyThrowable.<init>
> VFY: unable to resolve direct method 5583: Ljava/lang/Throwable;.<init> (Ljava/lang/String;Ljava/lang/Throwable;ZZ)V
> VFY: replacing opcode 0x70 at 0x0000



## Result with Xamarin.Forms 1.0.6186

No errors.



## Workaround

Instantiate a new `SwitchDemoPage()` on each call to `Navigation.PushAsync()`. That is, replace the following line:

> await ((Button)sender).Navigation.PushAsync(switchDemo);


... with:

> await ((Button)sender).Navigation.PushAsync(new SwitchDemoPage());




## Version information

Xamarin.Forms 1.2.2.6243

Xamarin   3.5.38.0 (0392433455d6cc9f503e2db4845a5889d394dc52)
Comment 2 Parmendra Kumar 2014-08-21 14:07:17 UTC
I have checked this issue and able to reproduce this, To reproduce this issue I
have followed the steps mentioned in bug description.
I observed that its work fine when we use:

await ((Button)sender).Navigation.PushAsync(new SwitchDemoPage());

Screencast: http://www.screencast.com/t/cylsWFJjfz

Application output: https://gist.github.com/Parmendrak/d10091753a96da044e21

Zip Xamarin Logs: https://gist.github.com/Parmendrak/761cf69c60f7371126af

Xamarin.Forms 1.2.2.6243

Environment info:

Microsoft Visual Studio Professional 2013
Version 12.0.30723.00 Update 3
Microsoft .NET Framework
Version 4.5.51641



Xamarin   3.5.39.0 (0a92fb56e49ed9add1c78e2c881ab6d71220d50f)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android
Comment 3 Eric Maupin 2014-09-16 20:52:32 UTC
Fixed for next update.
Comment 4 Indira 2014-12-04 07:50:49 UTC
I am developing the ios app using xamarin forms with 1.2.3.6257 stable channel on Mac os. I am facing the same issue with switch renderer. Is this issue fixed on stable channel?