NullReferenceException Class

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

The exception that is thrown when there is an attempt to dereference a null object reference.

Inheritance Hierarchy

System..::.Object
System..::.Exception
System..::.SystemException
System..::.NullReferenceException

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

Syntax

Public Class NullReferenceException _
    Inherits SystemException
public class NullReferenceException : SystemException

The NullReferenceException type exposes the following members.

Constructors

Name Description
NullReferenceException()()() Initializes a new instance of the NullReferenceException class, setting the Message property of the new instance to a system-supplied message that describes the error, such as "The value 'null' was found where an instance of an object was required." This message takes into account the current system culture.
NullReferenceException(String) Initializes a new instance of the NullReferenceException class with a specified error message.
NullReferenceException(String, Exception) Initializes a new instance of the NullReferenceException class with a specified error message and a reference to the inner exception that is the cause of this exception.

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Properties

Name Description
Data Gets a collection of key/value pairs that provide additional user-defined information about the exception. (Inherited from Exception.)
HelpLink Gets or sets a link to the help file associated with this exception. (Inherited from Exception.)
HResult Gets or sets HRESULT, a coded numerical value that is assigned to a specific exception. (Inherited from Exception.)
InnerException Gets the Exception instance that caused the current exception. (Inherited from Exception.)
Message Gets a message that describes the current exception. (Inherited from Exception.)
Source Gets or sets the name of the application or the object that causes the error. (Inherited from Exception.)
StackTrace Gets a string representation of the frames on the call stack at the time the current exception was thrown. (Inherited from Exception.)

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Methods

Name Description
Equals(Object) Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Finalize Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
GetBaseException When overridden in a derived class, returns the Exception that is the root cause of one or more subsequent exceptions. (Inherited from Exception.)
GetHashCode Serves as a hash function for a particular type. (Inherited from Object.)
GetType Gets the runtime type of the current instance. (Inherited from Exception.)
MemberwiseClone Creates a shallow copy of the current Object. (Inherited from Object.)
ToString Creates and returns a string representation of the current exception. (Inherited from Exception.)

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Remarks

Note that applications throw the ArgumentNullException exception rather than the NullReferenceException exception discussed here.

The following Microsoft intermediate language (MSIL) instructions throw NullReferenceException :

  • callvirt

  • cpblk

  • cpobj

  • initblk

  • ldelem.<type>

  • ldelema

  • ldfld

  • ldflda

  • ldind.<type>

  • ldlen

  • stelem.<type>

  • stfld

  • stind.<type>

  • throw

  • unbox

NullReferenceException uses the HRESULT COR_E_NULLREFERENCE, which has the value 0x80004003.

For a list of initial property values for an instance of NullReferenceException, see the NullReferenceException constructors.

Version Information

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Platforms

Windows Phone

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

See Also

Reference

System Namespace

Exception