Question

I am making a save option in my program that saves the changes to a file. I am using this code to save and get a MessageBox to show the result of the process I am getting an error on this line “Object reference not set to an instance of an object.”

     SaveFileCheck = StockHandler.SaveChangesToFile();

this is my code

    private void Save_Click(object sender, EventArgs e)
    {

        bool SaveFileCheck = false;
        var result = MessageBox.Show("Are you sure you want to Save the changes ?", "My   Application",
      MessageBoxButtons.YesNo, MessageBoxIcon.Asterisk);
        if (result == DialogResult.Yes)
        {           

                 SaveFileCheck = StockHandler.SaveChangesToFile();
                 if (SaveFileCheck)
                 {
                     MessageBox.Show("The process was a success");
                 }
                 else
                 {
                     MessageBox.Show("The process failed please make sure that the file is not been       used and try again");
                 } 

            //Save the file back


        }
    }
}
}

    public bool SaveChangesToFile() 
    {
        try
        {
            if (FileName != null)
            {
                using (StreamWriter Write = new StreamWriter(FileName, false))
                {
                    foreach (Stock s in FileStockList)
                    {
                        Write.Write(s.ToString() + "\r\n");

                    }

                }
            }
            else {
                return false;
            }

        }
        catch(IOException ex) 
        {
            return false;
            throw new ArgumentException("something went wrong an error" + ex + "is been cought");

        }
        return true;


    }

Answer 1

StockHandler is null.

If StockHandler is not a static class, you need to create an instance of it before you can call methods on it:

var handler = new StockHandler();
SaveFileCheck = handler.SaveChangesToFile();

Or, if StockHandler is a member variable:

StockHandler = new // something