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Dictionary(Of TKey, TValue).ICollection(Of KeyValuePair(Of TKey, TValue)).Add Method

Adds the specified value to the ICollection(Of T) with the specified key.

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

Private Sub Add ( _
	keyValuePair As KeyValuePair(Of TKey, TValue) _
) Implements ICollection(Of KeyValuePair(Of TKey, TValue)).Add


Type: System.Collections.Generic.KeyValuePair(Of TKey, TValue)
The KeyValuePair(Of TKey, TValue) structure representing the key and value to add to the Dictionary(Of TKey, TValue).


ICollection(Of T).Add(T)


The key of keyValuePair is Nothing.


An element with the same key already exists in the Dictionary(Of TKey, TValue).

If Count is less than the capacity, this method approaches an O(1) operation. If the capacity needs to be increased to accommodate the new element, this method becomes an O(n) operation, where n is Count.

The following example shows how to use the ICollection(Of KeyValuePair(Of TKey, TValue)).Add, ICollection(Of KeyValuePair(Of TKey, TValue)).Contains, ICollection(Of KeyValuePair(Of TKey, TValue)).CopyTo, and ICollection(Of KeyValuePair(Of TKey, TValue)).Remove methods of the System.Collections.Generic.ICollection(Of T) generic interface to manipulate a Dictionary(Of TKey, TValue) object.

Imports System
Imports System.Collections.Generic

Public Class Example

    Public Shared Sub Main() 

        ' Create a new dictionary of strings, with string keys, and
        ' access it through the generic ICollection interface. The
        ' generic ICollection interface views the dictionary as a
        ' collection of KeyValuePair objects with the same type
        ' arguments as the dictionary.
        Dim openWith As ICollection(Of KeyValuePair(Of String, String)) _
            = New Dictionary(Of String, String)

        ' Add some elements to the dictionary. When elements are 
        ' added through the ICollection(Of T) interface, the keys
        ' and values must be wrapped in KeyValuePair objects.
        openWith.Add(New KeyValuePair(Of String,String)("txt", "notepad.exe"))
        openWith.Add(New KeyValuePair(Of String,String)("bmp", "paint.exe"))
        openWith.Add(New KeyValuePair(Of String,String)("dib", "paint.exe"))
        openWith.Add(New KeyValuePair(Of String,String)("rtf", "wordpad.exe"))

        For Each element As KeyValuePair(Of String, String) in openWith
            Console.WriteLine("{0}, {1}", element.Key, element.Value)

        ' The Contains method also takes a KeyValuePair object.
        Console.WriteLine(vbLf & _
            "Contains(KeyValuePair(""txt"", ""notepad.exe"")): {0}", _
            openWith.Contains(New KeyValuePair(Of String,String)("txt", "notepad.exe")))

        ' The Remove method takes a KeyValuePair object.)
        ' Use the Remove method to remove a key/value pair.
        Console.WriteLine(vbLf &  _
            "Remove(New KeyValuePair(""dib"", ""paint.exe""))")
        openWith.Remove(New KeyValuePair(Of String,String)("dib", "paint.exe"))

        For Each element As KeyValuePair(Of String, String) in openWith
            Console.WriteLine("{0}, {1}", element.Key, element.Value)

        ' Create an array of KeyValuePair objects and copy the 
        ' contents of the dictionary to it. Subtract one from the
        ' array size because Visual Basic allocates an extra array
        ' element.
        Dim copy(openWith.Count - 1) As KeyValuePair(Of String, String)
        openWith.CopyTo(copy, 0)

        ' List the contents of the array.
        For Each element As KeyValuePair(Of String, String) in copy
            Console.WriteLine("{0}, {1}", element.Key, element.Value)

    End Sub

End Class

' This code example produces the following output:
'txt, notepad.exe
'bmp, paint.exe
'dib, paint.exe
'rtf, wordpad.exe
'Contains(KeyValuePair("txt", "notepad.exe")): True
'Remove(New KeyValuePair("dib", "paint.exe"))
'txt, notepad.exe
'bmp, paint.exe
'rtf, wordpad.exe
'txt, notepad.exe
'bmp, paint.exe
'rtf, wordpad.exe 

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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