RadListView: Unhandled exception on Items.Remove

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Completed

Last Updated: 09 Jul 2021 11:20 by ADMIN

Release R3 2021

Stoyan

Created on: 23 Jun 2021 15:07

Category: ListView

Type: Bug Report

RadListView: Unhandled exception on Items.Remove

System.NullReferenceException: 'Object reference not set to an instance of an object.' when removing items from the list:

 public Form1()
 {
     InitializeComponent();
     for (var i = 0; i < 30; i++)
     {
         var item = new ListViewDataItem();
         radListView2.Items.Insert(0, item);
         item[0] = i;
         item[1] = i;
         item[2] = i;
         item[3] = i;
     }
 }
private void radButton1_Click(object sender, EventArgs e)
{
    try
    {
        radListView2.BeginUpdate();

        foreach (var lvi in radListView2.Items.ToArray())
        {
            radListView2.Items.Remove(lvi);
           
        }
    }
    finally
    {
        radListView2.EndUpdate();
    }
}

3 comments

ADMIN

Nadya | Tech Support Engineer

Posted on: 28 Jun 2021 15:19

Hello, Stoyan,

I would like to follow up on this. Our developers are working on this issue and when the testing process is complete we would be able to introduce a fix in our upcoming LIB scheduled for next week. Make sure that you follow the feedback item in order to get notified when its status has changed. Thus, you should be able to download it from your Telerik account and test locally how it works with the fix.

I hope this information is useful. Please let me know if you have other questions.

Regards,
Nadya
Progress Telerik

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Stoyan

Posted on: 24 Jun 2021 06:58

Unfortunately, the workaround does not bring the necessary performance gain.

13 sec is a lot. Same code on standard ListView takes only 4 sec and only 0.13 sec with BeginUpdate() / EndUpdate().

radListView2.Items.Clear() is not an option, as in real case i have to remove only certain Items (most of them).

ADMIN

Nadya | Tech Support Engineer

Posted on: 23 Jun 2021 15:19

Hi, Stoyan,

To workaround use the SuspendLayout/ResumeLayout code block:

private void radButton1_Click(object sender, EventArgs e)
{
    try
    {
        radListView2.SuspendLayout();

        foreach (var lvi in radListView2.Items.ToArray())
        {
            radListView2.Items.Remove(lvi);
           
        }
    }
    finally
    {
        radListView2.ResumeLayout();
    }
}

Regards,
Nadya
Progress Telerik