FieldAttributes Enumeration
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FieldAttributes Enumeration

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

Specifies the attributes of a field.

This enumeration has a FlagsAttribute attribute that allows a bitwise combination of its member values.

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

'Declaration
<FlagsAttribute> _
Public Enumeration FieldAttributes

Member nameDescription
AssemblyThe field is accessible throughout the assembly.
FamANDAssemThe field is accessible only by subtypes in this assembly.
FamilyThe field is accessible only by type and subtypes.
FamORAssemThe field is accessible by subtypes anywhere, as well as throughout this assembly.
FieldAccessMaskSpecifies the access level of a given field.
HasDefaultThe field has a default value.
HasFieldMarshalThe field has marshaling information.
HasFieldRVAThe field has a relative virtual address (RVA). The RVA is the location of the method body in the current image, as an address relative to the start of the image file in which it is located.
InitOnlyThe field is initialized only, and cannot be written after initialization.
LiteralThe field's value is a compile-time (static or early bound) constant. Any attempt to set it throws FieldAccessException.
NotSerializedThe field does not have to be serialized when the type is remoted.
PinvokeImplReserved.
PrivateThe field is accessible only by the parent type.
PrivateScopeThe field cannot be referenced.
PublicThe field is accessible by any member for whom this scope is visible.
ReservedMaskReserved.
RTSpecialNameThe common language runtime (internal metadata APIs) should check the name encoding.
SpecialNameSpecifies a special field, with the name describing how the field is special.
StaticThe field represents the defined type, or else it is per-instance.

FieldAttributes uses the value from FieldAccessMask to mask off only the parts of the attribute value that pertain to the accessibility. For example, the following code determines if Attributes has the public bit set:

If (Attributes And FieldAttributes.FieldAccessMask) = _
    FieldAttributes.Public Then

To get the FieldAttributes, first get the class Type. From the Type, get the FieldInfo. From the FieldInfo, get the Attributes.

The enumerated value is a number representing the bitwise OR of the attributes implemented on the field.

This example shows how to test for the enumeration members that describe access level.


Imports System.Reflection

Public Class Example
   ' Declare three fields.
   ' The first field is private.
   Private m_field As String = "String A"

   'The second field is public.
   Public Field As String = "String B"

   ' The third field is public and const, hence also static
   ' and literal with a default value.
   Public Const FieldC As String = "String C"


   ' Make the output TextBlock visible to all Shared members.
   Private Shared outputBlock As System.Windows.Controls.TextBlock

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      Example.outputBlock = outputBlock

      ' Create an instance of the Example class.
      Dim ex As New Example()

      outputBlock.Text &= vbCrLf & "Reflection.FieldAttributes" & vbCrLf

      ' Get a Type object for Example, and a FieldInfo for each of
      ' the three fields. Use the FieldInfo to display field
      ' name, value for the Example object in d, and attributes.
      '
      Dim myType As Type = GetType(Example)

      Dim fiPrivate As FieldInfo = myType.GetField("m_field", _
          BindingFlags.NonPublic Or BindingFlags.Instance)
      DisplayField(ex, fiPrivate)

      Dim fiPublic As FieldInfo = myType.GetField("Field", _
          BindingFlags.Public Or BindingFlags.Instance)
      DisplayField(ex, fiPublic)

      Dim fiConstant As FieldInfo = myType.GetField("FieldC", _
          BindingFlags.Public Or BindingFlags.Static)
      DisplayField(ex, fiConstant)
   End Sub

   Shared Sub DisplayField(ByVal obj As Object, ByVal f As FieldInfo)

      Dim value As Object = "<not accessible>"
      If f.IsPublic Then
         value = f.GetValue(obj)
      End If

      ' Display the field name, value, and attributes.
      '
      outputBlock.Text &= String.Format("{0} = ""{1}""; attributes: {2}", _
          f.Name, value.ToString(), f.Attributes) & vbCrLf
   End Sub

End Class

' This code example produces the following output:
'
'm_field = "<not accessible>"; attributes: Private
'Field = "String B"; attributes: Public
'FieldC = "String C"; attributes: Public, Static, Literal, HasDefault


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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