Question

HttpServerUtility contains a public function called UrlEncode. It is not a shared function. HttpServerUtility does not have any public constructors.

Doing this fails:

Dim encodeMe As String = "a string to be encoded!"
HttpServerUtility.UrlEncode(encodeMe) 'Bombs out

This works, and is how Microsoft says to do it:

Dim instance As HttpServerUtility
Dim encodeMe As String = "a string to be encoded!"

instance.UrlEncode(encodeMe ) 'Works!

How did they accomplish this? You can’t instantiate an instance of it using a constructor, yet you can’t access UrlEncode by just referencing HttpServerUtility.UrlEncode.

EDIT: While I thoroughly enjoyed everyone getting into a big OO debate, I believe the problem is faulty MSDN documentation. The line “Dim instance As HttpServerUtility” should read “Dim instance As HttpServerUtility = Context.Server” The code which I included (which is from the MSDN documentation) does not actually work, and instead throws a null reference exception – just as you’d expect. Thank you, Jason!

Answer 1

Are you sure this works?

Dim instance As HttpServerUtility
Dim encodeMe As String = "a string to be encoded!"
instance.UrlEncode(encodeMe) 'Works!

This will give you a NullReferenceException at runtime (and the compiler will give you a warning that instance is not being assigned to). Seriously, Microsoft didn’t do anything here. The above code is disastrously wrong and will die at runtime.

And you can’t do this

Dim encodeMe As String = "a string to be encoded!"
HttpServerUtility.UrlEncode(encodeMe) 'Bombs out

because UrlEncode is not defined as a Shared method in HttpServerUtility.

You need a non-null instance of HttpServerUtility. The right way to use HttpServerUtility is like this:

Dim instance As HttpServerUtility = HttpContext.Server
Dim s As String = "Hello, World!"
Dim result As String = instance.UrlEncode(s)

Another option is to just use HttpUtility for which there is a Shared method HttpUtility.UrlEncode:

Dim s As String = "Hello, World!"
Dim result As String = HttpUtility.UrlEncode(s)