Bug 51410 - NRE when long pressing on listview cell item, and then interacting with cell
Summary: NRE when long pressing on listview cell item, and then interacting with cell
Alias: None
Product: Forms
Classification: Xamarin
Component: Android ()
Version: 2.3.3
Hardware: Macintosh Mac OS
: Normal normal
Target Milestone: ---
Assignee: Stephane Delcroix
Depends on:
Reported: 2017-01-11 14:33 UTC by tim.ahrentlov
Modified: 2017-06-20 00:00 UTC (History)
4 users (show)

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

Screenshot of problematic ListViewAdapter code (137.78 KB, image/png)
2017-01-11 14:33 UTC, tim.ahrentlov

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Description tim.ahrentlov 2017-01-11 14:33:07 UTC
Created attachment 19231 [details]
Screenshot of problematic ListViewAdapter code

When you:

1. have a listview in ListViewCachingStrategy.RecycleElement mode, 
2. long-press to bring it into ContextAction mode
3. interact with the cell(s) again in the listview

the app receives an NRE and crashes.

Problems is due to the following:

1. In ListViewAdapter.cs on line 217 & 218 you'll find 

   ActionModeContext = null;
   ContextView = null;  

2. Setting the ContextView calls the setter in base CellAdapter.cs which on line 67 do:

   var isSelected = (bool)ActionModeContext.GetValue(ListViewAdapter.IsSelectedProperty);

3. Notice that ActionModeContext is referenced in #2 even though it has just been set to null in #1
Comment 1 Stephane Delcroix 2017-02-15 14:17:30 UTC
Please provide a sample project triggering this issue so we can confirm it and fix it.

The code you are referencing has changed since...
Comment 2 Samantha Houts [MSFT] 2017-06-20 00:00:12 UTC
Because we have not received a reply to our request for more information we are closing this issue. If you are still encountering this issue, please reopen the ticket with the requested information. Thanks!