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NameObjectCollectionBase.BaseHasKeys Method

Gets a value indicating whether the NameObjectCollectionBase instance contains entries whose keys are not Nothing.

Namespace:  System.Collections.Specialized
Assembly:  System (in System.dll)
'Declaration
Protected Function BaseHasKeys As Boolean

Return Value

Type: System.Boolean
true if the NameObjectCollectionBase instance contains entries whose keys are not Nothing; otherwise, false.

This method is an O(1) operation.

The following code example uses BaseHasKeys to determine if the collection contains keys that are not Nothing.

Imports System
Imports System.Collections
Imports System.Collections.Specialized

Public Class MyCollection
   Inherits NameObjectCollectionBase

   Private _de As New DictionaryEntry()

   ' Gets a key-and-value pair (DictionaryEntry) using an index. 
   Default Public ReadOnly Property Item(index As Integer) As DictionaryEntry
      Get
         _de.Key = Me.BaseGetKey(index)
         _de.Value = Me.BaseGet(index)
         Return _de
      End Get 
   End Property 

   ' Creates an empty collection. 
   Public Sub New()
   End Sub 'New 

   ' Adds an entry to the collection. 
   Public Sub Add(key As [String], value As [Object])
      Me.BaseAdd(key, value)
   End Sub 'Add

   ' Gets a value indicating whether the collection contains keys that are not a null reference. 
   Public ReadOnly Property HasKeys() As [Boolean]
      Get 
         Return Me.BaseHasKeys()
      End Get 
   End Property 

End Class 'MyCollection


Public Class SamplesNameObjectCollectionBase   

   Public Shared Sub Main()

      ' Creates an empty MyCollection instance. 
      Dim myCol As New MyCollection()
      Console.WriteLine("Initial state of the collection (Count = {0}):", myCol.Count)
      PrintKeysAndValues(myCol)
      Console.WriteLine("HasKeys? {0}", myCol.HasKeys)

      Console.WriteLine()

      ' Adds an item to the collection.
      myCol.Add("blue", "sky")
      Console.WriteLine("Initial state of the collection (Count = {0}):", myCol.Count)
      PrintKeysAndValues(myCol)
      Console.WriteLine("HasKeys? {0}", myCol.HasKeys)

   End Sub 'Main

   Public Shared Sub PrintKeysAndValues(myCol As MyCollection)
      Dim i As Integer 
      For i = 0 To myCol.Count - 1
         Console.WriteLine("[{0}] : {1}, {2}", i, myCol(i).Key, myCol(i).Value)
      Next i
   End Sub 'PrintKeysAndValues

End Class 'SamplesNameObjectCollectionBase 


'This code produces the following output. 

'Initial state of the collection (Count = 0): 
'HasKeys? False 

'Initial state of the collection (Count = 1): 
'[0] : blue, sky 
'HasKeys? True

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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