C# Reflection: How to get class reference from string?

Question

Hi, I want to do this in C#, but I don't know how:

I have a string with a class name -e.g. "FooClass"- and I want to invoke a (static) method on this class: FooClass.MyMethod();

Obviously, I need to find a reference to the class via reflection, but how?

Answer 1

Via Type.GetType you can get the type information. You can use this class to get the method information and then invoke the method (for static methods, leave the first parameter null).

You might also need the Assembly name to correctly identify the type.

If the type is in the currently executing assembly or in Mscorlib.dll, it is sufficient to supply the type name qualified by its namespace.

Answer 2

You can use Type.GetType(string), but you'll need to know the full class name including namespace, and if it's not in the current assembly or mscorlib you'll need the assembly name instead. (Ideally, use Assembly.GetType(typeName) instead - I find that easier in terms of getting the assembly reference right!)

For instance:

// "I know String is in the same assembly as Int32..."
Type stringType = typeof(int).Assembly.GetType("System.String");

// "It's in the current assembly"
Type myType = Type.GetType("MyNamespace.MyType");

// "It's in System.Windows.Forms.dll..."
Type formType = Type.GetType ("System.Windows.Forms.Form, " + 
    "System.Windows.Forms, Version=2.0.0.0, Culture=neutral, " + 
    "PublicKeyToken=b77a5c561934e089");

Answer 3

You will want to use the Type.GetType method.

Here is a very simple example:

using System;
using System.Reflection;

class Program
{
    static void Main()
    {
     Type t = Type.GetType("Foo");
     MethodInfo method 
             = t.GetMethod("Bar", BindingFlags.Static | BindingFlags.Public);

     method.Invoke(null, null);
    }
}

class Foo
{
    public static void Bar()
    {
     Console.WriteLine("Bar");
    }
}

I say simple because it is very easy to find a type this way that is internal to the same assembly. Please see Jon's answer for a more thorough explanation as to what you will need to know about that. Once you have retrieved the type my example shows you how to invoke the method.