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GC.ReRegisterForFinalize Method

Requests that the system call the finalizer for the specified object for which SuppressFinalize has previously been called.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

'Declaration
Public Shared Sub ReRegisterForFinalize ( _
	obj As Object _
)

Parameters

obj
Type: System.Object

The object that a finalizer must be called for.

ExceptionCondition
ArgumentNullException

obj is Nothing.

The ReRegisterForFinalize method adds the obj parameter to the list of objects that request finalization before the garbage collector frees the object. The obj parameter must be the caller of this method.

Calling the ReRegisterForFinalize method does not guarantee that the garbage collector will call an object's finalizer.

By default, all objects that implement finalizers are added to the list of objects that require finalization; however, an object might have already been finalized or might have disabled finalization by calling the SuppressFinalize method.

A finalizer can use this method to resurrect itself or an object that it references.

The following example demonstrates how to use the ReRegisterForFinalize method to finalize an object a second time after garbage collection.

Imports System

Namespace ReRegisterForFinalizeExample
    Class MyMainClass
        Shared Sub Main()
            'Create a MyFinalizeObject. 
            Dim mfo As New MyFinalizeObject()

            'Release the reference to mfo.
            mfo = Nothing 

            'Force a garbage collection.
            GC.Collect()

            'At this point mfo will have gone through the first Finalize. 
            'There should now be a reference to mfo in the static 
            'MyFinalizeObject.currentInstance field.  Setting this value 
            'to null and forcing another garbage collection will now 
            'cause the object to Finalize permanently.
            MyFinalizeObject.currentInstance = Nothing
            GC.Collect()
        End Sub 
    End Class 

    Class MyFinalizeObject
        Public Shared currentInstance As MyFinalizeObject = Nothing 
        Private hasFinalized As Boolean = False 

        Protected Overrides Sub Finalize()
            If hasFinalized = False Then
                Console.WriteLine("First finalization")

                'Put this object back into a root by creating 
                'a reference to it.
                MyFinalizeObject.currentInstance = Me 

                'Indicate that this instance has finalized once.
                hasFinalized = True 

                'Place a reference to this object back in the 
                'finalization queue.
                GC.ReRegisterForFinalize(Me)
            Else
                Console.WriteLine("Second finalization")
            End If 
            MyBase.Finalize()
        End Sub 
    End Class 
End Namespace

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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