How can I throw a new NotImlementedException

Question

I was wondering if you could tell me how I can throw a new exception when a part of my code is not implemented,
have a look at my code:

        public void BuildHTML(string htmlfilenaddress, string htmlstring)
        {
            try
            {
                    using (FileStream fs = new FileStream(htmlfilenaddress, FileMode.Create))
                    {
                        using (StreamWriter writer = new StreamWriter(fs, Encoding.UTF8))
                        {
                            writer.Write(htmlstringbegin + htmlstring + htmlstringend);
                        }
                    }
            }
 
            catch (NotImplementedException)
            {
                throw new NotImplementedException();
            }
        }

I want the exception to be caught when the writer writes null value.
Thank you.

Vulpes · Answer

Try this: public void BuildHTML(string htmlfilenaddress string htmlstring) { using (FileStream fs = new FileStream(htmlfilenaddress FileMode.Create)) { using (StreamWriter writer = new StreamWriter(fs Encoding.UTF8)) { string text = htmlstringbegin + htmlstring + htmlstringend; try { if (text != null) { writer.Write(text); } else { throw new NotImplementedException(Null value can't be written to file); } } catch (NotImplementedException ex) { MessageBox.Show(ex.Message); } } } }