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Type.GetField Method (String, BindingFlags)

Searches for the specified field, using the specified binding constraints.

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

'Declaration
Public MustOverride Function GetField ( _
	name As String, _
	bindingAttr As BindingFlags _
) As FieldInfo
'Usage
Dim instance As Type
Dim name As String
Dim bindingAttr As BindingFlags
Dim returnValue As FieldInfo

returnValue = instance.GetField(name, bindingAttr)
public abstract FieldInfo GetField (
	String name, 
	BindingFlags bindingAttr
)
public abstract function GetField (
	name : String, 
	bindingAttr : BindingFlags
) : FieldInfo

Parameters

name

The String containing the name of the data field to get.

bindingAttr

A bitmask comprised of one or more BindingFlags that specify how the search is conducted.

-or-

Zero, to return a null reference (Nothing in Visual Basic).

Return Value

A FieldInfo object representing the field that matches the specified requirements, if found; otherwise, a null reference (Nothing in Visual Basic).

Exception typeCondition

ArgumentNullException

name is a null reference (Nothing in Visual Basic).

The following table shows what members of a base class are returned by the Get methods when reflecting on a type.

Member Type

Static

Non-Static

Constructor

No

No

Field

No

Yes. A field is always hide-by-name-and-signature.

Event

Not applicable

The common type system rule is that the inheritance is the same as that of the methods that implement the property. Reflection treats properties as hide-by-name-and-signature. See note 2 below.

Method

No

Yes. A method (both virtual and non-virtual) can be hide-by-name or hide-by-name-and-signature.

Nested Type

No

No

Property

Not applicable

The common type system rule is that the inheritance is the same as that of the methods that implement the property. Reflection treats properties as hide-by-name-and-signature. See note 2 below.

  1. Hide-by-name-and-signature considers all of the parts of the signature, including custom modifiers, return types, parameter types, sentinels, and unmanaged calling conventions. This is a binary comparison.

  2. For reflection, properties and events are hide-by-name-and-signature. If you have a property with both a get and a set accessor in the base class, but the derived class has only a get accessor, the derived class property hides the base class property, and you will not be able to access the setter on the base class.

  3. Custom attributes are not part of the common type system.

The following BindingFlags filter flags can be used to define which fields to include in the search:

  • You must specify either BindingFlags.Instance or BindingFlags.Static in order to get a return.

  • Specify BindingFlags.Public to include public fields in the search.

  • Specify BindingFlags.NonPublic to include non-public fields (that is, private and protected fields) in the search.

  • Specify BindingFlags.FlattenHierarchy to include public and protected static members up the hierarchy; private static members in inherited classes are not included.

The following BindingFlags modifier flags can be used to change how the search works:

  • BindingFlags.IgnoreCase to ignore the case of name.

  • BindingFlags.DeclaredOnly to search only the fields declared on the Type, not fields that were simply inherited.

See System.Reflection.BindingFlags for more information.

If the requested type is non-public and the caller does not have ReflectionPermission to reflect non-public objects outside the current assembly, this method returns a null reference (Nothing in Visual Basic).

If the current Type represents a constructed generic type, this method returns the FieldInfo with the type parameters replaced by the appropriate type arguments.

If the current Type represents a type parameter in the definition of a generic type or generic method, this method searches the fields of the class constraint.

The following example gets the Type object for the specified class, obtains the FieldInfo object for the field that matches the specified binding flags, and displays the value of the field.


Imports System
Imports System.Reflection
Imports Microsoft.VisualBasic

Public Class MyFieldClassA
    Public Field As String = "A Field"
End Class 'MyFieldClassA

Public Class MyFieldClassB
    Private myField As String = "B Field"

    Public Property Field() As String
        Get
            Return myField
        End Get
        Set(ByVal Value As String)
            If myField <> value Then
                myField = value
            End If
        End Set
    End Property
End Class 'MyFieldClassB


Public Class MyFieldInfoClass

    Public Shared Sub Main()
        Dim myFieldObjectB As New MyFieldClassB()
        Dim myFieldObjectA As New MyFieldClassA()

        Dim myTypeA As Type = GetType(MyFieldClassA)
        Dim myFieldInfo As FieldInfo = myTypeA.GetField("Field")

        Dim myTypeB As Type = GetType(MyFieldClassB)
        Dim myFieldInfo1 As FieldInfo = myTypeB.GetField("myField", _
            BindingFlags.NonPublic Or BindingFlags.Instance)

        Console.WriteLine("The value of the public field is: '{0}'", _
            myFieldInfo.GetValue(myFieldObjectA))
        Console.WriteLine("The value of the private field is: '{0}'", _
            myFieldInfo1.GetValue(myFieldObjectB))
    End Sub 'Main

End Class 'MyFieldInfoClass



import System.*;
import System.Reflection.*;
import System.Security.*;

public class MyFieldClassA
{
    public String field = "A Field";

    /** @property 
     */
    public String get_Field()
    {
        return field;
    } //get_Field

    /** @property 
     */
    public void set_Field(String value)
    {
        if (!(field.Equals(value))) {
            field = value;
        }
    } //set_Field
} //MyFieldClassA

public class MyFieldClassB
{
    public String field = "B Field";

    /** @property 
     */
    public String get_Field()
    {
        return field;
    } //get_Field

    /** @property 
     */
    public void set_Field(String value)
    {
        if (!(field.Equals(value))) {
            field = value;
        }
    } //set_Field
} //MyFieldClassB

public class MyFieldInfoClass
{
    public static void main(String[] args)
    {
        try {
            MyFieldClassB myFieldObjectB = new MyFieldClassB();
            MyFieldClassA myFieldObjectA = new MyFieldClassA();
            Type myTypeA = Type.GetType("MyFieldClassA");
            FieldInfo myFieldInfo = myTypeA.GetField("field");
            Type myTypeB = Type.GetType("MyFieldClassB");
            FieldInfo myFieldInfo1 = myTypeB.GetField("field", 
                BindingFlags.Public | BindingFlags.Instance);
            Console.WriteLine("The value of the field is : {0} ",
                myFieldInfo.GetValue(myFieldObjectA));
            Console.WriteLine("The value of the field is : {0} ",
                myFieldInfo1.GetValue(myFieldObjectB));
        }
        catch (SecurityException e) {
            Console.WriteLine("Exception Raised!");
            Console.WriteLine("Message :" + e.get_Message());
        }
        catch (ArgumentNullException e) {
            Console.WriteLine("Exception Raised!");
            Console.WriteLine("Message :" + e.get_Message());
        }
        catch (System.Exception e) {
            Console.WriteLine("Exception Raised!");
            Console.WriteLine("Message :" + e.get_Message());
        }
    } //main
} //MyFieldInfoClass

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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