Creating framework objects from class name strings

[Oenone]

Hi all,

If I have the name in a string of one of the framework's core classes (such
as "System.Collections.ArrayList"), what's the easiest way for me to create
an instance of the appropriate class?

In VB6 I would have simply used CreateObject, is there an equally simple way
in VB.NET?

Thanks,

 

[Herfried K. Wagner [MVP]]

If I have the name in a string of one of the framework's core classes
(such as "System.Collections.ArrayList"), what's the easiest way for me to
create an instance of the appropriate class?

'Activator.CreateInstance'.

 

[Oenone]

'Activator.CreateInstance'.

Thanks Herfried, got this working fine as follows:

\\\
Dim list As IList
Dim collName As String

collName = "System.Collections.ArrayList"
list =
DirectCast(Activator.CreateInstance(System.Type.GetType(collName)), IList)
///

However, when I set collName to "Microsoft.VisualBasic.Collection" (to get
one of the old VB6-style collections), System.Type.GetType() returns
Nothing. Do you know why?

I'm trying to write some code that knows how to deal with all different
sorts of collections, and it's handling everything except for
Microsoft.VisualBasic.Collection objects just fine. It'd be a shame to have
to put a separate If clause in to specifically create these objects...

Thanks,

 

[Herfried K. Wagner [MVP]]

\\\
Dim list As IList
Dim collName As String

collName = "System.Collections.ArrayList"
list =
DirectCast(Activator.CreateInstance(System.Type.GetType(collName)), IList)
///

However, when I set collName to "Microsoft.VisualBasic.Collection" (to get
one of the old VB6-style collections), System.Type.GetType() returns
Nothing. Do you know why?

It doesn't know which assembly the type is defined in. You'll have to know
the assembly which contains the type:

\\\
Dim o As Object
For Each a As [Assembly] In AppDomain.CurrentDomain.GetAssemblies()
If a.FullName.StartsWith("Microsoft.VisualBasic,") Then
o = a.CreateInstance("Microsoft.VisualBasic.Collection")
Exit For
End If
Next a
///

 

[Guest]

Just curious as to where one would need to create a Framework object and how
it would be used...Thanks as I'm just learning!