Bug 22389 - Android - ListView Item doesn't get removed when an item deleted from ItemSource
Summary: Android - ListView Item doesn't get removed when an item deleted from ItemSource
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 1.2.2
Hardware: PC Mac OS
: Normal normal
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2014-08-27 02:42 UTC by Prashant Cholachagudda
Modified: 2014-09-23 00:13 UTC (History)
6 users (show)

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

Testcase (29.95 KB, application/zip)
2014-08-27 02:42 UTC, Prashant Cholachagudda

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Description Prashant Cholachagudda 2014-08-27 02:42:28 UTC
Created attachment 7815 [details]

ListView Item doesn't get removed when an item removed/deleted from ItemSource.
When you either delete an item or scroll the listview you will see that a complete mismatch of what is being tapped and the item we think is being tapped.
Comment 2 Rajneesh Kumar 2014-08-27 05:17:26 UTC
I have checked this issue and getting the same behavior except that when I click on "Delete" then item gets remove from ListView. On behalf of mismatch of what item being tapped and  item we think is  being tapped, I confirmed this. 

My observations are:

I am able to delete the selected item on emulator and device both, and item gets remove from the ListView.

I observed that on simulator when item being tapped is different then the item we think with the following output to the application output window:


I observed that on device every time when item being tapped is different then the item we think with the following output to the application output window:

"[ResourceType] Failure getting entry for 0x010802c0 (t=7 e=704) in package 0 (error -75)

I also observed that sometimes when I tap a item I get text with popup  "ITEM IS NULL".

Please let me know if I am missing something.

Screencast: http://www.screencast.com/t/Se5gOqwyh0Q

Environment Info;

=== Xamarin Studio ===

Version 5.2 (build 386)
Installation UUID: 011d70a5-dede-428b-ab04-ef451c2e539d
	Mono 3.8.0 ((no/62a857e)
	GTK+ 2.24.23 (Raleigh theme)

	Package version: 308000007

=== Xamarin.Android ===

Version: 4.14.0 (Enterprise Edition)
Android SDK: /Users/MM/Desktop/android-sdk-macosx
	Supported Android versions:
		2.1   (API level 7)
		2.2   (API level 8)
		2.3   (API level 10)
		3.1   (API level 12)
		3.2   (API level 13)
		4.0   (API level 14)
		4.0.3 (API level 15)
		4.1   (API level 16)
		4.2   (API level 17)
		4.3   (API level 18)
		4.4   (API level 19)
Java SDK: /usr
java version "1.7.0_65"
Java(TM) SE Runtime Environment (build 1.7.0_65-b17)
Java HotSpot(TM) 64-Bit Server VM (build 24.65-b04, mixed mode)

=== Apple Developer Tools ===

Xcode 5.1.1 (5085)
Build 5B1008

=== Xamarin.iOS ===

Version: (Enterprise Edition)
Hash: 606f31a
Build date: 2014-08-01 15:27:48-0400

=== Xamarin.Mac ===

Version: (Enterprise Edition)

=== Build Information ===

Release ID: 502000386
Git revision: e6a54dee5376e6e7a2d9982695b060fddc09e65d
Build date: 2014-08-04 14:03:28-04
Xamarin addins: 2b5a5c26ac2ee74c6e91a8d24ef44d0ca9cb74d0

=== Operating System ===

Mac OS X 10.9.2
Darwin MacMini.local 13.1.0 Darwin Kernel Version 13.1.0
    Thu Jan 16 19:40:37 PST 2014
    root:xnu-2422.90.20~2/RELEASE_X86_64 x86_64
Comment 4 Eric Maupin 2014-09-23 00:13:03 UTC
In the test case, GestureGridRenderer has a bug in it that creates this behavior. OnElementChanged is fired when the element changes, this happens on first setup but also happens in places where renderers are being reused, like virtualization in ListView. However in GestureGridRenderer, the condition `if (grid == null && e.NewElement != null)` will only be true once. This means that new elements will not update the GestureListener with the new GestureGrid being represented by this renderer. So, as a result when a renderer gets reused it still has the first grid that was ever given to this renderer. Simplifying the conditional to `if (e.NewElement != null)` fixes it.