Interlocked.Exchange Method (Object, Object)

Sets an object to a specified value and returns a reference to the original object, as an atomic operation.

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

public static Object Exchange (
	ref Object location1,
	Object value
)
public static Object Exchange (
	/** @ref */ Object location1, 
	Object value
)
Not applicable.

Parameters

location1

The variable to set to the specified value.

value

The value to which the location1 parameter is set.

Return Value

The original value of location1.

Exception typeCondition

ArgumentNullException

The address of location1 is a null pointer.

Beginning with .NET Framework version 2.0, the Exchange method overload provides a type-safe alternative for reference types.

The following code example shows the syntax for using Exchange with any reference type object.

using System;
using System.Threading;

class AtomicTest
{
    static void Main()
    {
        AtomicExchange atomicExchange = new AtomicExchange();
        Thread firstThread = 
            new Thread(new ThreadStart(atomicExchange.Switch));
        firstThread.Start();
    }
}

class AtomicExchange
{
    class SomeType{}

    // To use Interlocked.Exchange, someType1 
    // must be declared as type Object.
    object   someType1;
    SomeType someType2;

    public AtomicExchange() 
    {
        someType1 = new SomeType();
        someType2 = new SomeType();
    }

    public void Switch()
    {
        someType2 = (SomeType)Interlocked.Exchange(
            ref someType1, (object)someType2);
    }
}

import System.*;
import System.Threading.*;
import System.Threading.Thread;

class AtomicTest
{
    public static void main(String[] args)
    {
        AtomicExchange atomicExchange = new AtomicExchange();
        Thread firstThread = new Thread(
            new ThreadStart(atomicExchange.Switch));
        firstThread.Start();
    } //main
} //AtomicTest

class AtomicExchange
{
    class SomeType
    {
    } //SomeType

    // To use Interlocked.Exchange, someType1 
    // must be declared as type Object.
    private System.Object someType1;
    private SomeType someType2;

    public AtomicExchange()
    {
        someType1 = new SomeType();
        someType2 = new SomeType();
    } //AtomicExchange

    public void Switch()
    {
        someType2 = ((SomeType)(Interlocked.Exchange(someType1, 
            ((Object)(someType2)))));
    } //Switch
} //AtomicExchange

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, 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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