How to use IDisposable Interface(not disposing inner objects)

Question

First of all thanks and Pardon me if my English is not good. I tried a lot to get how to implement IDisposable Interface. As per pictures i got from net i implemented the interface. In my test project i tried a lot so if i'm loading some image to memory i could see IDisposible works as per my expectation.To see the memory(PF Usage) I used task manager.Here "test.bmp" is 5mb file

These are the three experiments i have done

    Dim i As Integer = 0
    While (i < 1000)
        i = i + 1
        Dim bmp As New Bitmap("D:\test.bmp")
    End While

It killed my memory. Then i tried

    Dim i As Integer = 0
    While (i < 1000)
        i = i + 1
        Using bmp As New Bitmap("D:\test.bmp")
        End Using
    End While

PF was steady until the 1000. Means memory released propery.

then i tried

    Dim i As Integer = 0
    Dim dt As DateTime = DateTime.Now
    While (i < 1000)
        i = i + 1
        Using oTestDispose As New clsTestDispose
        End Using
    End While
Public Class clsTestDispose
Implements IDisposable

Dim bmp As New Bitmap("D:\test.bmp")

Private disposedValue As Boolean = False        ' To detect redundant calls

' IDisposable
Protected Overridable Sub Dispose(ByVal disposing As Boolean)
    If Not Me.disposedValue Then
        If disposing Then
            ' TODO: free unmanaged resources when explicitly called
            Me.Dispose()
        End If

        ' TODO: free shared unmanaged resources
    End If
    Me.disposedValue = True
End Sub

#Region " IDisposable Support "
' This code added by Visual Basic to correctly implement the disposable pattern.
Public Sub Dispose() Implements IDisposable.Dispose
    ' Do not change this code.  Put cleanup code in Dispose(ByVal disposing As Boolean)        above.
    Dispose(True)
    GC.SuppressFinalize(Me)
End Sub
#End Region

 End Class

This code is telling "System.StackOverFlowException". Why the dispose is not clearing the image object inside it?

Answer 1

Because you are overriding the Dispose method and calling it again inside with Me.Dispose, this method runs recursively.

You could call Dispose with `MyBase:

MyBase.Dispose()

This will call the Dispose on the derived class, preventing it to loop and end in a StackOverflowException.