Bug 16902 - Unhandled NullReferenceException in System.ComponentModel.BindingList<T>
Summary: Unhandled NullReferenceException in System.ComponentModel.BindingList<T>
Alias: None
Product: Class Libraries
Classification: Mono
Component: System ()
Version: 3.2.x
Hardware: All All
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2013-12-19 18:26 UTC by Scott McArthur
Modified: 2014-12-09 08:24 UTC (History)
2 users (show)

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

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Description Scott McArthur 2013-12-19 18:26:45 UTC
Description of Problem:
Unhandled NullReferenceException in System.ComponentModel.BindingList<T>. 

Steps to reproduce the problem:
1. Create a class the implements an INotifyPropertyChanged

public class Foo : INotifyPropertyChanged
  private string _name;

  public event PropertyChangedEventHandler PropertyChanged;

  public string Name 
    get { return _name; }
      _name = value;

      if (PropertyChanged != null)
        PropertyChanged(this, new PropertyChangedEventArgs("Name"));

2. Create a BindList of its type:

var list = new BindingList<Foo>();
list.Insert(0, null);

Actual Results:
`NullReferenceException` thrown on Insert

Expected Results:
Item added to collection, without exception

How often does this happen?
All the time

Additional Information:
A check on line #246 (item as INotifyPropertyChanged).PropertyChanged += Item_PropertyChanged;
should be made before casting item, as it may be null.
Comment 1 Scott McArthur 2013-12-20 05:51:47 UTC
Created pull request for fix. https://github.com/mono/mono/pull/842
Comment 2 Marek Safar 2014-12-09 08:24:26 UTC
Already fixed in mono 3.10