So what basically is reflection:

Using a class library methods at runtime without adding its reference in your project is done through Reflection.  In this article I will show you how to use reflection using a simple example.
Let’s first create a Class Library.

let’s code our ReflectionTest Class

Namespace reflectionclass
Public Class ClsReflection

#Region "Methods"
Public Function add(ByVal x As Integer, ByVal y As Integer) As Integer
Return x + y
End Function

Public Function [sub](ByVal x As Integer, ByVal y As Integer) As Integer
Return x - y
End Function
#End Region

End Class
End Namespace

let’s make a test project now. Add a windows form application to the solution.

Now let’s design our Form.

so after putting two command buttons two listview controls and four textbox controls our form should look like this.

Let’s code our form now

Imports System.Reflection

Public Class Form1
Dim objAssembly As Assembly
'Declare an array of Types to Hold All Classes of Assembly
Dim arrTypes As Type()
Dim objType As Type
'Delcare an array to hold all methods of Assembly
Dim arrMethods As MethodInfo()
Dim objMethod As MethodInfo

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Try
OpenFileDialog1.ShowDialog()
txtAssembly.Text = OpenFileDialog1.FileName
objAssembly = System.Reflection.Assembly.LoadFrom(txtAssembly.Text)
For Each cls In objAssembly.GetTypes
'
If cls.FullName.IndexOf("ClsReflection") > 0 Then
lstClasses.Items.Add(cls.FullName)
End If
Next
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End Sub

Private Sub lstClasses_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstClasses.SelectedIndexChanged
Try
lstMethods.Items.Clear()
objType = objAssembly.GetType(Me.lstClasses.SelectedItem.ToString)
arrMethods = objType.GetMethods
For Each method In objType.GetMethods
lstMethods.Items.Add(method.Name)
Next
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End Sub

Private Sub cmdCallMethod_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdCallMethod.Click
Try
objMethod = objType.GetMethod(lstMethods.SelectedItem.ToString())
Dim obj As Object
obj = Activator.CreateInstance(objType)
'Let's Create Array of Parameter
Dim objParameters As Object() = {Int32.Parse(txtNum1.Text), Int32.Parse(txtNum2.Text)}
'If there is no parameter in method then on the place of oo pass the null
txtResult.Text = objMethod.Invoke(obj, objParameters).ToString()
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End Sub
End Class

Select Add and put any two numbers in the first and second number textbox and click on execute method and you should get the result.

Now select Sub and enter any two number in first number and second number textbox and press execute method and you should get the desired result.

This article show you how you can call method dynamically at runtime without referencing the assembly in your project. It is a very basic example but I think it will help you to understand how reflection works in .Net.

If you have any point you are not getting in this article please let me know i will try to explain.

Happy Coding!

Kshitij