ObjectDisposedException同时显示表单

Question

当我需要显示一张表单时，我总是得到一个ObjectDisposedExpection。你们知道怎么做吗？在NotitiesForm.Show()的前文中，我得到了错误ObjectDisposedExpection。我正在用VisualStudioUltimal2012 C#编程。

RichTextBox NotitiesTB = new RichTextBox();
private Form NotitiesForm;

/// <summary>
/// 
/// </summary>
/// <param name="label"></param>
/// 
public void NotitiesLatenZien()
{
    if (filename != null)
    {                
        BRTSignal signal = new BRTSignal(filename);
        BRTEventRepository Notities = new BRTEventRepository(signal);

        List<IBRTNote> note = Notities.ReadNotes();

        BRTEventService TijdNotities = new BRTEventService(signal);
        TijdNotities.MakeNoteTimesRelativeToTrack(note, 1);

        //TextBox NotitiesTB = new TextBox();
        //NotitiesTB.Name = "Notities";

        if (NotitiesForm == null)
        {
            NotitiesForm = new Form();
        }              

        NotitiesForm.Height = 600;
        NotitiesForm.Width = 1000;
        NotitiesForm.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
        NotitiesForm.MaximizeBox = false;
        NotitiesForm.Disposed +=NotitiesForm_Disposed;

        NotitiesForm.Text = "Notities";

        NotitiesTB.Multiline = true;
        NotitiesTB.Height = 600;
        NotitiesTB.Width = 980;
        NotitiesTB.ReadOnly = true;

        NotitiesTB.Clear();

        //NotitiesTB.Click += NotitiesTB_Click;

        //NotitiesTB.SelectionStart = Convert.ToInt32(referenceLineSelectedPage);

        NotitiesTB.ScrollBars = System.Windows.Forms.RichTextBoxScrollBars.Both;

        NotitiesTB.Name = "Notities";

        NotitiesForm.Controls.Add(NotitiesTB);

        foreach (IBRTNote notes in Notities.ReadNotes())
        {
            //string test = Convert.ToString((notes.Time));
            //textBox1.Text = String.Concat(textBox1.Text, string.Concat(Environment.NewLine, notes.Text));
            if (NotitiesTB.Text == "")
            {
                NotitiesTB.Text += new BRTToDotNET.RTDateTime((long)notes.Time).ToDotNet().ToString() + "     " + notes.Text;
            }
            else
            {
                NotitiesTB.Text += "\r\n" + new BRTToDotNET.RTDateTime((long)notes.Time).ToDotNet().ToString() + "     " + notes.Text;
            }
            //MessageBox.Show("\r\n" + notes.Text);
            NotitiesForm.Show();
            NotitiesForm.BringToFront();
        }
    }
    else
    {
        MessageBox.Show("Er blijkt een .sig file te missen. Controleer of u een .sig file heeft ingeladen.");
    }
}

private void NotitiesForm_Disposed(object sender, EventArgs e)
{
    NotitiesForm = null;
} 

Answer 1

你发布的代码看起来“足够好”。也就是说，在释放对象时设置NotitiesForm变量，如果对象为null，则创建一个新变量。只要所有这些代码都在主UI线程中执行，该部分就可以了。

但是请注意，Form中的所有控件都是在释放Form时释放的。因此，您的NotitiesTB控件将在第一次关闭NotitiesForm时被释放。然后将该控件添加到您创建的下一个Form实例中，当它显示时，您将得到异常，因为您试图显示包含已被释放的控件的Form。

正确的方法是设计一个实际的Form子类，该子类已经包含所需的RichTextBox实例。然后，您不必一直将一个新实例添加到您创建的Form的每个新实例中。

否则，您需要创建一个新的RichTextBox实例，以便与您创建的每个新的Form实例一起使用，例如，在您拥有NotitiesForm = new Form();语句的同一个地方。