Confused about how to retrieve gridview row values

I have a basic appalication that reads from a text file then splits string values values by comma and finally add this values to a gridview as rows.This my code to achieve this and its works.

 using (StreamReader reader = new StreamReader(fileName))
 {
      string line;
      while ((line = reader.ReadLine())!=null)
      {
           liste.Add(line.Split(',')[0]);
      }
 }

 for (int i = 0; i < liste.Count; i++)
 {
      dataGridView1.Rows.Add();
      dataGridView1.Rows[i].Cells[1].Value = liste[i];
 }

Gridview has two columns first one is checkbox and the other one is textbox column The problem is I need to get this row values from the gridview .But I am getting null pointer exception .So I have decided to check like this way

 for (int i = 0; i < dataGridView1.RowCount; i++)
 {
      MessageBox.Show(dataGridView1.Rows[i].Cells[1].ToString());
 }

and realized result are not as expected.Messagebox display this result

datagridviewtextboxcell {columnindex=1 rowindex=0}

What am I doing wrong?