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StringCollection Class

Represents a collection of strings.

Namespace:  System.Collections.Specialized
Assembly:  System (in System.dll)

'Declaration
<SerializableAttribute> _
Public Class StringCollection _
	Implements IList, ICollection, IEnumerable
'Usage
Dim instance As StringCollection

StringCollection accepts Nothing as a valid value and allows duplicate elements.

String comparisons are case-sensitive.

Elements in this collection can be accessed using an integer index. Indexes in this collection are zero-based.

The following code example demonstrates several of the properties and methods of StringCollection.

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

Public Class SamplesStringCollection

   Public Shared Sub Main()

      ' Create and initializes a new StringCollection. 
      Dim myCol As New StringCollection()

      ' Add a range of elements from an array to the end of the StringCollection. 
      Dim myArr() As String = {"RED", "orange", "yellow", "RED", "green", "blue", "RED", "indigo", "violet", "RED"}
      myCol.AddRange(myArr)

      ' Display the contents of the collection using foreach. This is the preferred method.
      Console.WriteLine("Displays the elements using foreach:")
      PrintValues1(myCol)

      ' Display the contents of the collection using the enumerator.
      Console.WriteLine("Displays the elements using the IEnumerator:")
      PrintValues2(myCol)

      ' Display the contents of the collection using the Count and Item properties.
      Console.WriteLine("Displays the elements using the Count and Item properties:")
      PrintValues3(myCol)

      ' Add one element to the end of the StringCollection and insert another at index 3.
      myCol.Add("* white")
      myCol.Insert(3, "* gray")

      Console.WriteLine("After adding ""* white"" to the end and inserting ""* gray"" at index 3:")
      PrintValues1(myCol)

      ' Remove one element from the StringCollection.
      myCol.Remove("yellow")

      Console.WriteLine("After removing ""yellow"":")
      PrintValues1(myCol)

      ' Remove all occurrences of a value from the StringCollection. 
      Dim i As Integer = myCol.IndexOf("RED")
      While i > - 1
         myCol.RemoveAt(i)
         i = myCol.IndexOf("RED")
      End While 

      ' Verify that all occurrences of "RED" are gone. 
      If myCol.Contains("RED") Then
         Console.WriteLine("*** The collection still contains ""RED"".")
      End If 
      Console.WriteLine("After removing all occurrences of ""RED"":")
      PrintValues1(myCol)

      ' Copy the collection to a new array starting at index 0. 
      Dim myArr2(myCol.Count) As String
      myCol.CopyTo(myArr2, 0)

      Console.WriteLine("The new array contains:")
      For i = 0 To myArr2.Length - 1
         Console.WriteLine("   [{0}] {1}", i, myArr2(i))
      Next i
      Console.WriteLine()

      ' Clears the entire collection.
      myCol.Clear()

      Console.WriteLine("After clearing the collection:")
      PrintValues1(myCol)
   End Sub 'Main


   ' Uses the foreach statement which hides the complexity of the enumerator. 
   ' NOTE: The foreach statement is the preferred way of enumerating the contents of a collection. 
   Public Shared Sub PrintValues1(myCol As StringCollection)
      Dim obj As [Object]
      For Each obj In  myCol
         Console.WriteLine("   {0}", obj)
      Next obj
      Console.WriteLine()
   End Sub 'PrintValues1


   ' Uses the enumerator.  
   ' NOTE: The foreach statement is the preferred way of enumerating the contents of a collection. 
   Public Shared Sub PrintValues2(myCol As StringCollection)
      Dim myEnumerator As StringEnumerator = myCol.GetEnumerator()
      While myEnumerator.MoveNext()
         Console.WriteLine("   {0}", myEnumerator.Current)
      End While
      Console.WriteLine()
   End Sub 'PrintValues2


   ' Uses the Count and Item properties. 
   Public Shared Sub PrintValues3(myCol As StringCollection)
      Dim i As Integer 
      For i = 0 To myCol.Count - 1
         Console.WriteLine("   {0}", myCol(i))
      Next i
      Console.WriteLine()
   End Sub 'PrintValues3

End Class 'SamplesStringCollection 


'This code produces the following output. 

'Displays the elements using foreach: 
'   RED 
'   orange 
'   yellow 
'   RED 
'   green 
'   blue 
'   RED 
'   indigo 
'   violet 
'   RED 

'Displays the elements using the IEnumerator: 
'   RED 
'   orange 
'   yellow 
'   RED 
'   green 
'   blue 
'   RED 
'   indigo 
'   violet 
'   RED 

'Displays the elements using the Count and Item properties: 
'   RED 
'   orange 
'   yellow 
'   RED 
'   green 
'   blue 
'   RED 
'   indigo 
'   violet 
'   RED 

'After adding "* white" to the end and inserting "* gray" at index 3: 
'   RED 
'   orange 
'   yellow 
'   * gray 
'   RED 
'   green 
'   blue 
'   RED 
'   indigo 
'   violet 
'   RED 
'   * white 

'After removing "yellow": 
'   RED 
'   orange 
'   * gray 
'   RED 
'   green 
'   blue 
'   RED 
'   indigo 
'   violet 
'   RED 
'   * white 

'After removing all occurrences of "RED": 
'   orange 
'   * gray 
'   green 
'   blue 
'   indigo 
'   violet 
'   * white 

'The new array contains: 
'   [0] orange 
'   [1] * gray 
'   [2] green 
'   [3] blue 
'   [4] indigo 
'   [5] violet 
'   [6] * white 

'After clearing the collection: 
'

System.Object
  System.Collections.Specialized.StringCollection
    System.Configuration.CommaDelimitedStringCollection

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

This implementation does not provide a synchronized (thread safe) wrapper for a StringCollection, but derived classes can create their own synchronized versions of the StringCollection using the SyncRoot property.

Enumerating through a collection is intrinsically not a thread safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
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