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POObject reference not set to an instance of an object. (System.NullReferenceException)
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copied!<p>I'm working on my first project outside college. I have a method that should loop through a list and add the elements by parameters to SQL database. The list is populated in another class. When I'm debugging it I get that the value of list is "null", but I use the same list in different class and I get all the items of it. </p> <pre><code>public class AddToDatabase { CopyPDF copyPdf = new CopyPDF(); DBConnection db = new DBConnection(); private List<string> calledList = null; public string error; public void AddPdfToDatabase() { try { string connectionString = db.getTxtContent(); calledList = copyPdf.GetList(); //The GetList method from the other class returns the List I need. using (SqlConnection conn = new SqlConnection(connectionString)) using (DbCommand cmd = conn.CreateCommand()) { cmd.CommandText = "INSERT INTO pdf (Name, Location) VALUES (@names, @locations)"; DbParameter n = cmd.CreateParameter(); DbParameter l = cmd.CreateParameter(); n.ParameterName = "@names"; l.ParameterName = "@locations"; cmd.CommandType = CommandType.Text; conn.Open(); using (DbTransaction tran = conn.BeginTransaction()) { cmd.Transaction = tran; foreach (string line in calledList) //I get the error here { n.Value = line; l.Value = line; cmd.ExecuteNonQuery(); } tran.Commit(); conn.Close(); } } } catch (SqlException ex) { string str; str = "Source:" + ex.Source; str += "\n" + "Number" + ex.Number.ToString(); str += "\n" + "Message" + ex.Message; error = str; } } } </code></pre> <h3>CopyPDF Class :</h3> <pre><code>public class CopyPDF { private List<string> list = null; public void addToList() { //create list list = new List<string>(); //Directory of the PDF files on the network DirectoryInfo dir = new DirectoryInfo(@"W:\"); //get all .PDF files from the given directory FileInfo[] pdffiles = dir.GetFiles("*.pdf"); foreach (FileInfo f in pdffiles) { //remove .pdf, .PDF ending of the strings string yourString = f.Name; string[] remove = {".pdf", ".PDF"}; foreach (string suffix in remove) { if (yourString.EndsWith(suffix)) { yourString = yourString.Remove(yourString.Length - suffix.Length); break; } } //add the string to generic List list.Add(yourString); } } //return the list as PUBLIC so will be accessible from other classes public List<string> GetList() { return list; } //this is the class where I have the GetList(). Thank you for helping </code></pre>

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