C# Reflection: Instantiate an object with string class name

Question

my situation is the next: I\'m working with Visual C# 2010 express developing a Windows Forms Application. When the user logins, dinamically build a menustrip with options l

Answer 1

Try specifying your class this way:

ContabilidadNamespace.Contabilidad, ContabilidadAssembly

Answer 2

Try this

Form frmConta= (Form)Activator.CreateInstance(null, "AccountingSA.Contabilidad").Unwrap();

Answer 3

Use the fully-qualified name of the type:

Type t = assembly.GetType("AccountingSA.Contabilidad");

From the documentation for Assembly.GetType(string):

name Type: System.String The full name of the type. [...] The name parameter includes the namespace but not the assembly.

Answer 4

You should add the namespace:

assembly.GetType("AccountingSA.Contabilidad");

Answer 5

You're trying to use the name of the class without specifying the namespace. This should be fine:

Assembly assembly = Assembly.Load("AccountingSA");
Type t = assembly.GetType("AccountingSA.Contabilidad");
Form frmConta = (Form)Activator.CreateInstance(t);

Every version of GetType requires the fully-qualified type name; the benefit of using Assembly.GetType is that at least you don't need to also include the assembly name, but as documented you still need the namespace:

The name parameter includes the namespace but not the assembly.

Note that to diagnose something similar in the future, it would have been worth looking at the value of t after the second line - it will be null, which is why the third line threw an exception.

Answer 6

Its too late in the thread to answer, but the earlier answer, in current .NET framework (4.7), not working (The line Assembly assembly = Assembly.Load("AccountingSA"); always throws FileIOException). Currently, working code is (Use Type directly)

Type t = Type.GetType("AccountingSA.Contabilidad");
Form frmConta = (Form)Activator.CreateInstance(t);

or other way using Assembly is

Assembly assembly = typeof(Form).Assembly;
Type t = assembly.GetType("AccountingSA.Contabilidad");
Form frmConta = (Form)Activator.CreateInstance(t);