C# adding object code error

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This is my code

C#

// this creates a new label every times panel1 is clicked
 Label label = new Label();
 private void panel1_Click(object sender, EventArgs e)
 {

     if ((treeView1.SelectedNode.Text == "Instruments") || (treeView1.SelectedNode.Text == "Drums") || (treeView1.SelectedNode.Text == "Pre-Made Beats") || (treeView1.SelectedNode.Text == "") )
     {
     }
     else
     {
         label.Visible = true;
         label.Location = new Point(lastClicked.X, 10);
         label.Text = treeView1.SelectedNode.Text;
         panel1.Controls.Add(label);
     }

     }

This is where my error is

SQL

if ((treeView1.SelectedNode.Text == "Instruments") || (treeView1.SelectedNode.Text == "Drums") || (treeView1.SelectedNode.Text == "Pre-Made Beats") || (treeView1.SelectedNode.Text == "") )
    {
    }

this is what the error is

Object reference not set to an instance of an object.

I'm trying so when it is clicked that nothing will happen if those are selected or nothing is selected

Posted 10-Apr-12 20:43pm

C.CoderCreator

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OriginalGriff · Answer 1 · 2012-04-10T21:11:00

Solution 1

You need to test first:

C#

private void panel1_Click(object sender, EventArgs e)
   {
   if (treeView1.SelectedNode != null)
      {
      ...
      }
   }

In addition, that does not add a new label each time the panel is clicked - you need to put the

C#

label = new Label();

inside the method for that to happen.

Posted 10-Apr-12 21:11pm

OriginalGriff

Comments

[no name] 11-Apr-12 5:48am

the null code didn't work

OriginalGriff 11-Apr-12 6:19am

What do you mean by "didn't work" - was there an error?

[no name] 11-Apr-12 6:20am

yes there was still the same error

OriginalGriff 11-Apr-12 6:23am

Can you paste the exact code, and indicate where it gave the null reference?

[no name] 11-Apr-12 20:25pm

private void panel1_Click(object sender, EventArgs e)
{

if ((treeView1.SelectedNode.Text == "Instruments") ||
(treeView1.SelectedNode.Text == "Drums") ||
(treeView1.SelectedNode.Text == "Pre-Made Beats") || (treeView1.SelectedNode != null))
{

}
else
{
Label label = new Label();
label.Visible = true;
label.Location = new Point(lastClicked.X, 10);
label.Text = treeView1.SelectedNode.Text;
panel1.Controls.Add(label);
}

}
and got the error in the if statement

OriginalGriff 12-Apr-12 3:17am

Look back at my code! :laugh:
private void panel1_Click(object sender, EventArgs e)
{
if (treeView1.SelectedNode != null)
{
if ((treeView1.SelectedNode.Text == "Instruments") ||
(treeView1.SelectedNode.Text == "Drums") ||
(treeView1.SelectedNode.Text == "Pre-Made Beats"))
{
}
else
{
Label label = new Label();
label.Visible = true;
label.Location = new Point(lastClicked.X, 10);
label.Text = treeView1.SelectedNode.Text;
panel1.Controls.Add(label);
}
}
}
If you don't do the null test first, then the null value will be used and you will get the error!

[no name] 12-Apr-12 5:14am

Sorry, I just did a silly mistake

OriginalGriff 12-Apr-12 5:31am

Easy to do! :laugh: