An unhandled exception of type 'System.NullReferenceException'

[willemr]

Hi Everybody,

I've been working with webservices. But I keep stumbling on the same error.

An unhandled exception of type 'System.NullReferenceException'
Additional information: Object reference not set to an instance of an object.

This is my piece of code

  getKeyTags _keyTags = new getKeyTags();
            _keyTags.login = login;
            KeyTagBean[] keyTags = null;
            lock (wService)
            {
                keyTags = wService.getKeyTags(_keyTags);
            }
            Hashtable keyTagHash = new Hashtable();
            foreach (KeyTagBean bean in keyTags)
            {
               keyTagHash.Add(bean.keyTagID, bean);
            }  
            dataGridView1.DataSource = keyTagHash;     

When I get the error, the keyTagHash.Add line highlights.


Can anyone help me please?

THanks

[Dheeraj Joshi]

is bean.keyTagID is unique?

Regards
Dheeraj Joshi

[willemr]

yes it is.

[ThatThatGuy]

@willemr
keyTags = wService.getKeyTags(_keyTags);
is resulting a null value to keyTags... check it out first on debug

[tlhintoq]

Original Poster: "How do I fix a 'object reference not set to an instance of an object' error?

The line your code stopped on while debugging holds all your answers.
One of the variables/objects was created but not initialized. For example:

string TempString;// Created but not initialized so this is still null
//versus
string TempString = string.empty;

Debug your project again. This time, when it breaks on a line look at the Locals pallet to see which variable/object is null. You can also hover your mouse over each variable and the hothelp will shows its value. One of them will be null.

[willemr]

Thanks Guys, I managed to fix it.