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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)

public static void ReRegisterForFinalize (
	Object obj
)
public static void ReRegisterForFinalize (
	Object obj
)
public static function ReRegisterForFinalize (
	obj : Object
)

Parameters

obj

The object for which a finalizer must be called.

Exception typeCondition

ArgumentNullException

obj is a null reference (Nothing in Visual Basic).

The ReRegisterForFinalize method adds obj 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 it references.

using System;

namespace ReRegisterForFinalizeExample
{
    class MyMainClass
    {
        static void Main()
        {
            // Create a MyFinalizeObject.
            MyFinalizeObject mfo = new MyFinalizeObject();

            // Release the reference to mfo.
            mfo = null;

            // 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 = null;
            GC.Collect();
        }
    }

    class MyFinalizeObject
    {
        public static MyFinalizeObject currentInstance = null;
        private bool hasFinalized = false;

        ~MyFinalizeObject()
        {
            if(hasFinalized == false)
            {
                Console.WriteLine("First finalization");
            
                // Put this object back into a root by creating
                // a reference to it.
                MyFinalizeObject.currentInstance = this;
            
                // Indicate that this instance has finalized once.
                hasFinalized = true;

                // Place a reference to this object back in the
                // finalization queue.
                GC.ReRegisterForFinalize(this);
            }
            else
            {
                Console.WriteLine("Second finalization");
            }
        }
    }
}

package ReRegisterForFinalizeExample;

import System.* ;

class MyMainClass
{
    public static void main(String[] args)
    {
        // Create a MyFinalizeObject.
        MyFinalizeObject mfo = new MyFinalizeObject();

        // Release the reference to mfo.
        mfo = null;

        // 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 = null;
        GC.Collect();
    } //main
} //MyMainClass

class MyFinalizeObject
{
    public static MyFinalizeObject currentInstance = null;
    private boolean hasFinalized = false;

    public void finalize()
    {
        if (hasFinalized == false) {
            Console.WriteLine("First finalization");

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

            // Indicate that this instance has finalized once.
            hasFinalized = true;

            // Place a reference to this object back in the
            // finalization queue.
            GC.ReRegisterForFinalize(this);
        }
        else {
            Console.WriteLine("Second finalization");
        }

        try {
            super.finalize();
        }
        catch (System.Exception e) {
            Console.WriteLine(e.get_Message());
        }
    } //finalize
} //MyFinalizeObject

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0
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