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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
)
Not applicable.

Parameters

obj

The object that a finalizer must be called for.

Exception typeCondition

ArgumentNullException

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

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.

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 Server 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 Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0
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