Interlocked.Exchange Method (Object, Object)


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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


Type: System.Object

The variable to set to the specified value.

Type: System.Object

The value to which the location1 parameter is set.

Return Value

Type: System.Object

The original value of location1.

Exception Condition

The address of location1 is a null pointer.

Beginning with .NET Framework version 2.0, the Exchange<T>(T, T) 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));

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);

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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