Last Updated: 11 Apr 2022 14:53 by n/a
Created on: 11 Apr 2022 14:42
Category: ListView
Type: Bug Report
ListView: [Android] Null Reference Exception when using Range Collection and ListView is initially grouped
Null Reference Exception is thrown when the ListView is initially grouped with more than 1 group descriptor and then the control is populated using Range Observable collection. 
Posted on: 11 Apr 2022 14:53

Hello -


This does not work for us.  Applying the grouping after populating is not possible.  Data is being added to the list by RFID scanning asynchronously.  Imaging we get 5 new tags of data, we have to ungroup the list, add the items, then regroup it.  Then 5 more items may come thru in the next second, etc.  This also prevents using the normal ObservableCollection for same reason.  Adding 5 times to the collection would raise the change even 5 times instead of 1 time using the RangeObservableCollection.  INotifyCollectionChanged supports multiple items being manipulated at once (eg, multiple add or remove) so this control should also support multiple changes.



Posted on: 11 Apr 2022 14:47


Approach 1) Apply grouping after populating the ListView with Items

Approach 2) Replace ObservableRangeCollection with ObservableCollection(only if the usage of range collection is not mandatory).

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