.NET (Core and Framework)

private void fillListView(IList list)
{
        this.listView.Items.Clear();
        this.listView.BeginUpdate();
        this.progressBar.Visible = true;
        this.backgroundWorker.RunWorkerAsync(list);
}
private void backgroundWorker_DoWork(System.Object sender, System.ComponentModel.DoWorkEventArgs e)
{
    System.ComponentModel.BackgroundWorker worker = sender as System.ComponentModel.BackgroundWorker;
    IList list = (IList)e.Argument;
    for(System.Int32 i = 0; i < list.Count; i++)
    {
        System.Windows.Forms.ListViewItem item = getListViewItem(list[i]);
        // necessary or else the main UI thread will still "freeze"
        System.Threading.Thread.Sleep(10);
        System.Int32 progress = (System.Int32)System.Math.Ceiling((System.Single)(i + 1) / (System.Single)(list.Count) * 100.0f);
        worker.ReportProgress(progress, item);
    }
}
private void backgroundWorker_ProgressChanged(System.Object sender, System.ComponentModel.ProgressChangedEventArgs e)
{
    System.Windows.Forms.ListViewItem item = (System.Windows.Forms.ListViewItem)e.UserState;
    this.listView.Items.Add(item);
    this.progressBar.Value = e.ProgressPercentage;
}
private void backgroundWorker_RunWorkerCompleted(System.Object sender, System.ComponentModel.RunWorkerCompletedEventArgs e)
{
    this.progressBar.Visible = false;
    this.listView.EndUpdate();
}