Question

I am using TreeView control in WinForm.

I am trying to use the following code, but getting “NullReferenceException”.
I am following the syntax provided i.e. tree.Nodes[key].Nodes.Add(key,text)

I don’t know whats wrong with the code.

Please have a look at the code i used –

tvTree.Nodes.Add("Subjects", "Subjects");
tvTree.Nodes["Subjects"].Nodes.Add("Physics", "Physics");

tvTree.Nodes["Physics"].Nodes.Add("PhysicsP1", "Paper1");
tvTree.Nodes["Physics"].Nodes.Add("PhysicsP2", "Paper2");
tvTree.Nodes["Physics"].Nodes.Add("PhysicsP3", "Paper3");

Thanks for sharing your time.

Answer 1

Also you may achieve this with

        tvTree.Nodes.Add("Subjects", "Subjects");
        tvTree.Nodes["Subjects"].Nodes.Add("Physics", "Physics");

        var phyNode = tvTree.Nodes.Find("Physics", true).First();

        phyNode.Nodes.Add("PhysicsP1", "Paper1");
        phyNode.Nodes.Add("PhysicsP2", "Paper2");
        phyNode.Nodes.Add("PhysicsP3", "Paper3");