object reference not set to an instance of anobjectException

Question

Hi All,

I am getting the exception "object reference not set to an instance of an object Exception".

I wrote logic in buttion1 click event in "Form1"

 private void button1_Click(object sender, EventArgs e)

        {
          Form2 test = new Form2(richTextBox1.Text);

            test.Show();

        }

I wrote following logic in Form2:

namespace Form1

{

    public partial class Form2 : Form

    {

        private string p;

        public Form2()

        {

            InitializeComponent();

        }

        public Form2(string p)

        {           

            this.p = p;

            

                using (StringReader reader = new StringReader(p))

        {

            

            string line;

            while ((line = reader.ReadLine()) != null)

            {

               listBox1.Items.Add(line);

            }

        }

            

        }

    }

}

I am getting the following exception:
System.NullReferenceException was unhandled


when I use InitializeComponent(); in  public Form2(string p) {} constructor, It is working fine. Please explain me why it happens?


Advance thanks, Darma