Object.ReferenceEquals Method
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Updated: October 2010
Determines whether the specified object instances are the same instance.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Shared Function ReferenceEquals ( _
objA As Object, _
objB As Object _
) As Boolean
public static bool ReferenceEquals(
Object objA,
Object objB
)
Parameters
- objA
Type: System.Object
The first object to compare.
- objB
Type: System.Object
The second object to compare.
Return Value
Type: System.Boolean
true if objA is the same instance as objB or if both are nulla null reference (Nothing in Visual Basic); otherwise, false.
Remarks
Unlike the Equals method and the equality operator, the ReferenceEquals method cannot be overridden. Because of this, if you want to test two object references for equality and are unsure about the implementation of the Equals method, you can call the ReferenceEquals method. However, note that if objA and objB are value types, they are boxed before they are passed to the ReferenceEquals method.
Examples
The following code example uses ReferenceEquals to determine if two objects are the same instance.
Public Class Example
Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
Dim o As Object = Nothing
Dim p As Object = Nothing
Dim q As New Object
outputBlock.Text += Object.ReferenceEquals(o, p) & vbCrLf
p = q
outputBlock.Text += Object.ReferenceEquals(p, q) & vbCrLf
outputBlock.Text += Object.ReferenceEquals(o, p) & vbCrLf
End Sub
End Class
' This code produces the following output:
'
' True
' True
' False
'
using System;
class Example
{
public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
object o = null;
object p = null;
object q = new Object();
outputBlock.Text += Object.ReferenceEquals(o, p) + "\n";
p = q;
outputBlock.Text += Object.ReferenceEquals(p, q) + "\n";
outputBlock.Text += Object.ReferenceEquals(o, p) + "\n";
}
}
/*
This code produces the following output.
True
True
False
*/
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0
XNA Framework
Supported in: Xbox 360, Windows Phone OS 7.0
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.
Change History
Date |
History |
Reason |
|---|---|---|
October 2010 |
Added the Remarks section. |
Customer feedback. |