Static/Shared classes are used when a class provides functionality which is not specific to

any instance. In short if you want an object to be shared between multiple instances you

will use a static/Shared class.

Following are features of Static/Shared classes :-

? They can not be instantiated. By default a object is created on the first method

? Static/Shared classes can not be inherited.

? Static/Shared classes can have only static members.

? Static/Shared classes can have only static constructor.

Note :- In CD there is a folder “WindowsShared” which has a sample code for shared

variables.Below is a snippet. It has a “AddCount” function which increments a static

“intCount” variable. In form there are two buttons which creates a new object and displays

the count of the static variable. Even though the object is created and destroyed, the variable

values does not change. It retains its old value.

Public Class ClsShared

Shared intCount As Integer

Public Function AddCount() As Integer

intCount = intCount + 1

Return intCount

End Function

End Class

Public Class FrmSharedClasses

Inherits System.Windows.Forms.Form

Private Sub CmdInstance1_Click(ByVal sender As System.Object, ByVal

e As System.EventArgs) Handles CmdInstance1.Click

Dim pobjClsShared As New ClsShared()

MessageBox.Show(“The count at this moment is” &

pobjClsShared.AddCount.ToString())

End Sub

Private Sub CmdInstance2_Click(ByVal sender As System.Object, ByVal

e As System.EventArgs) Handles CmdInstance2.Click

Dim pobjClsShared As New ClsShared()

MessageBox.Show(“The count at this moment is” &

pobjClsShared.AddCount.ToString())

call to that object.

214

End Sub

End Class