How can I get a treeview from another form?

Question

I am trying to implement a search function in a treeview.
So, I want to get the value to be retrieved in a new form. But my code error with this message. System.NullReferenceException

Form1.cs

public TreeView TreeView1
{
    get { return treeView1; }
    set { this.treeView1 = value; }
}

Form2.cs

public void btnClick(object sender, EventArgs e)
{
    Form1 form1 = new Form1();
    label1.Text = form1.TreeView1.SelectedNode.Text;
}

Answer 1

Try this:

    Form1 form1 = new Form1();

    form1.TreeView1.AfterSelect += (sender1, e1) =>            
        label1.Text = e1.Node?.Text ?? string.Empty;
        
    form1.Show();

You need create and show the form. Then, we manage AfterSelect event of TreeView of the new created form to set the Label text.