What are constructors and destructor?

Welcome Dibya,

Below i explain constructor and destructor with examples.

Constructor is special method, which controls over the initialization of object. It is used for variable initialization. When we create an object of the class then the constructor within the class is automatically called. It is used with the keyword new before sub in vb.net

Ex
Public Class Form1
    Inherits System.Windows.Forms.Form

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim a As New raj
        a.kunal()
        Dim b As New rahul("pintu")
        Dim c As New rahul(10, 10)
    End Sub
    Public Class raj
        Public Sub New()
            MsgBox("Hello raj constructor")
        End Sub
        Public Sub kunal()
            MsgBox("Hello kunal")
        End Sub
    End Class
    Public Class rahul
        Public Sub New(ByVal x As String)
            MsgBox("Hello" & x)
        End Sub
        Public Sub New(ByVal x As Integer, ByVal y As Integer)
            MsgBox(x + y)
        End Sub
    End Class
End Class


Destructor release the memory of the object created by the constructor. It is of two types dispose and finalize .In dispose we have to intentionally call dispose destructor. But in finalize it is called automatically when the last reference of the object is released

Ex

Public Class Form1
    Inherits System.Windows.Forms.Form

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim a As New raj
        a.dispose()
    End Sub
    Public Class raj
        Public Sub New()
            MsgBox("Instant constructor of raj")
        End Sub
        Shared Sub New()
            MsgBox("Shared constructor of raj")
        End Sub
        Public Overloads Sub dispose()
            MsgBox("Dispose destructor of raj")
        End Sub
        Protected Overrides Sub finalize()
            MsgBox("Finalize destructor of raj")
        End Sub
    End Class
End Class



Thanks
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