nullreferenceexception

This question already has an answer here: What is a NullReferenceException, and how do I fix it? 31 answers Why there's a NullReferenceException when trying to set value of X in the code below? It works fine when I use new keyword when initializing B , but why it compiles fine without new and then fails during runtime? https://dotnetfiddle.net/YNvPog public class A { public _B B; public class _B { public int X; } } public class Program { public static void Main() { var a=new A{ B={ X=1 } }; } } Initialization syntax can be tricky. In your code, you're trying to set the value of a.B.X without

If I have a long list of objects that each has the possibility of returning null within a "Linq where" clause, e.g. SomeSource.Where(srcItem=>(srcItem.DataMembers["SomeText"].Connection.ConnectedTo as Type1).Handler.ForceInvocation == true)); the indexer can return null and the "as" operator may return null. It is possible that the object does not have a connection (ie. The property is null). If a null is encountered anywhere, I would like the where clause to return "false" for the item being evaluated. Instead, it aborts with a null reference exception. It appears to me that this would be

Ever since I started programming this question has been annoying me, not "where is my code null" but specifically is there any way to get the type of the object that is null from the exception? Failing that, can anyone provide a blog post or msdn article that explains the reason why the .NET Framework doesn't (or can't) provide these details? Um... Because it's null. In C#, a reference type is a pointer to something. A null pointer isn't pointing to anything. You are asking, "What type of thing would this point to if it was pointing to something". That's sort of like getting a blank sheet of

I'm trying to copy a List 'usrs' which is created in an Inner class to a different list 'team_memebers'. After copying I try to iterate 'team_memebers' in the FOR loop, but I get a 'null object reference' error. The 'users' list contains the returned objects, tested via debug prints. public class ListNodeActivity extends AppCompatActivity { private ParseObject parse_task=null; private List<String> team_memebers=null; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_list_node); Toolbar toolbar = (Toolbar)

I am mucking about with WPF glyphs and documents and have run into a null reference exception in the .Net 4 framework. I extract and save true-type fonts to disk as .ttf files, then try to create Glyphs based on the fonts. The first time I save a font to disk and instantiate a GlyphTypeface based on the font after creating a GlyphTypeface from another font in the same folder I get a null reference exception. Say I have fonts A and B. B has not been saved to disk (A may or may not have been saved to disk; that doesn't seem to matter): 1) save B to disk in the same folder as A, 2) create

I keep getting this error when trying to navigate to my LogOn page: System.NullReferenceException: Object reference not set to an instance of an object The line of code that is throwing the error on is: <%= Html.OpenIdSelectorScripts(this, options, null)%>. Does anyone know why this line of code would be throwing an error? Have a look at this link: Gougle-Groups/DotNetOpenAuth : "I suspect though that you're missing the OpenIdDiscover named route in your global.asax.cs file." 来源： https://stackoverflow.com/questions/4138534/html-openidselectorscripts-helper-method-throwing