Why the controls not update, when call method from other form

Question

My TextBox and Label Text property does not update when I call a method from another Form?

Here is the code

//Form1 Codes
private void treeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
{
    Form2 frm= new Form2 ();
    frm.UpdateText(this.treeView1.SelectedNode.Text.ToString());
    this.Close();
}

//Form2 codes
//show Form1
private void Button1_Click(object sender, EventArgs e)
{
    Form1 Frm = new Form1();
    Frm.ShowDialog();
}

//update Textbox and lable
public void UpdateText(string text)
{
    this.label1.Text = text;
    textBox1.Text = text;
    label1.Refresh();
}

Thanks in advance.

score 2 · Accepted Answer · answered Dec 17 '12 at 08:16

You are creating new instance of Form2 (which in not visible to client, because you don't show it) and updating it's label. What you need is updating label on existing instance of Form2. So, you need to pass instance of Form2 to Form1, which you create in Button1_Click event handler. Or (the better way) you need to define property on Form1 and read that property when Form1 is closed:

Form1 code

public string SelectedValue 
{ 
     get { return treeView1.SelectedNode.Text; }
}    

void treeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
{
     // this means that user clicked on tree view
     DialogResult = DialogResult.OK;
     Close();
}

Form2 code

private void Button1_Click(object sender, EventArgs e)
{
    using(Form1 frm1 = new Form1())
    {
       if(frm1.ShowDialog() != DialogResult.OK)
          return;

       UpdateText(frm1.SelectedValue);
    }
}

public void UpdateText(string text)
{
    label1.Text = text;
    textBox1.Text = text;
    label1.Refresh();
}

Why the controls not update, when call method from other form

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