object reference set to an instance of an object

Question

I make richtextbox disable by choosing "cleared" on a combobox, and I get this error "object reference set to an instance of an object"

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    try
    {
        if (comboBox1.SelectedItem.ToString() == "Cleared")
        {
            richTextBox1.Enabled = false;
            richTextBox1.Text = "";
        }
        else
        {
            richTextBox1.Enabled = true;
        }
    }
    catch (Exception a)
    {
        MessageBox.Show(a.Message);
    }
}

http://stackoverflow.com/a/21737654/2864740 (I wrote this now, just for you.) — user2864740, Feb 12 '14 at 19:26

score 1 · Answer 1 · answered Feb 12 '14 at 19:09

1

try:

if (comboBox1.SelectedItem != null && comboBox1.SelectedItem.ToString() == "Cleared")

answered Feb 12 '14 at 19:09

JBrooks

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score 0 · Accepted Answer · answered Feb 12 '14 at 19:11

Since it seems unlikely that richTextBox1 is null (since it's probably given a value as initialization), the only other possibility is that comboBox1.SelectedItem is null. The simplest fix would be to check for null:

    if (comboBox1.SelectedItem != null && comboBox1.SelectedItem.ToString() == "Cleared")
    {
        richTextBox1.Enabled = false;
        richTextBox1.Text = "";
    }

object reference set to an instance of an object

2 Answers2