Articolo
11/18/2011

Activator.CreateInstance Method (Type)

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Creates an instance of the specified type by using that type's default constructor.

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

Syntax

'Declaration
Public Shared Function CreateInstance ( _
    type As Type _
) As Object

public static Object CreateInstance(
    Type type
)

Parameters

type
Type: System.Type
The type of object to create.

Return Value

Type: System.Object
A reference to the newly created object.

Exceptions

Exception	Condition
ArgumentNullException	type is nulla null reference (Nothing in Visual Basic).
ArgumentException	type is not a RuntimeType. -or- type is an open generic type (that is, the ContainsGenericParameters property returns true).
NotSupportedException	type is a TypeBuilder. -or- Creation of TypedReference, Void, and RuntimeArgumentHandle types, or arrays of those types, is not supported.
TargetInvocationException	The constructor being called throws an exception.
MethodAccessException	The caller does not have permission to call this constructor.
MemberAccessException	Cannot create an instance of an abstract class, or this member was invoked with a late-binding mechanism.
MissingMethodException	No matching public constructor was found.
COMException	type is a COM object but the class identifier used to obtain the type is invalid, or the identified class is not registered.
TypeLoadException	type is not a valid type.

Remarks

The type and the constructor to be invoked must be accessible. For example, if you are using AssemblyBuilder to create a dynamic assembly, you can invoke an internal constructor (Friend constructor in Visual Basic) for a type defined within the dynamic assembly. However, if you are using DynamicMethod to create a dynamic method, you cannot invoke internal constructors, because the dynamic method is hosted in an anonymous module in a system-provided assembly.

Platform Notes

Silverlight for Windows Phone

For types that do not have constructors defined, the CreateInstance method throws a MemberAccessException exception instead of a MissingMethodException exception.

Examples

The following code example demonstrates how to call the CreateInstance(Type) method. This code example is part of a larger example provided for the Activator class.

Dim sbType As Type = GetType(StringBuilder)

' Create an instance of the StringBuilder type using Activator.CreateInstance
' and the parameterless constructor.
Dim o As Object = Activator.CreateInstance(sbType)

' Append a string to the StringBuilder object and display the StringBuilder,
' late bound.
sbType.InvokeMember("Append", _
   BindingFlags.Public Or BindingFlags.Instance Or BindingFlags.InvokeMethod, _
   Type.DefaultBinder, _
   o, New Object() { "Hello, there." })
outputBlock.Text &= o.ToString() & vbCrLf

Type sbType = typeof(StringBuilder);

// Create an instance of the StringBuilder type using Activator.CreateInstance
// and the parameterless constructor.
object o = Activator.CreateInstance(sbType);

// Append a string to the StringBuilder object and display the StringBuilder,
// late bound.
sbType.InvokeMember("Append", 
   BindingFlags.Public | BindingFlags.Instance | BindingFlags.InvokeMethod, 
   Type.DefaultBinder, 
   o, new object[] {"Hello, there."});
outputBlock.Text += o.ToString() + "\n";

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.

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