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

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

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

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

Syntax

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

Parameters

Implements

ICollection<(Of <(T>)>)..::.Add(T)

Exceptions

Exception Condition
ArgumentNullException

The key of keyValuePair is nullNothingnullptra null reference (Nothing in Visual Basic).

ArgumentException

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

Remarks

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.

Examples

The following example shows how to use explicit interface implementations of the System.Collections.Generic..::.ICollection<(Of <(T>)>) generic interface to manipulate a Dictionary<(Of <(TKey, TValue>)>) object.

Imports System.Collections.Generic

Public Class Example

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

      ' 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"))

      outputBlock.Text &= vbCrLf
      For Each element As KeyValuePair(Of String, String) In openWith
         outputBlock.Text &= String.Format("{0}, {1}", element.Key, element.Value) & vbCrLf
      Next

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

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

      outputBlock.Text &= vbCrLf
      For Each element As KeyValuePair(Of String, String) In openWith
         outputBlock.Text &= String.Format("{0}, {1}", element.Key, element.Value) & vbCrLf
      Next

      ' 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.
      '
      outputBlock.Text &= vbCrLf
      For Each element As KeyValuePair(Of String, String) In copy
         outputBlock.Text &= String.Format("{0}, {1}", element.Key, element.Value) & vbCrLf
      Next

   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 
using System;
using System.Collections.Generic;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // 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.
      //
      ICollection<KeyValuePair<String, String>> openWith =
          new Dictionary<String, String>();

      // Add some elements to the dictionary. When elements are 
      // added through the ICollection<T> interface, the keys
      // and values must be wrapped in KeyValuePair objects.
      //
      openWith.Add(new KeyValuePair<String, String>("txt", "notepad.exe"));
      openWith.Add(new KeyValuePair<String, String>("bmp", "paint.exe"));
      openWith.Add(new KeyValuePair<String, String>("dib", "paint.exe"));
      openWith.Add(new KeyValuePair<String, String>("rtf", "wordpad.exe"));

      outputBlock.Text += "\n";
      foreach (KeyValuePair<string, string> element in openWith)
      {
         outputBlock.Text += String.Format("{0}, {1}", element.Key, element.Value) + "\n";
      }

      // The Contains method also takes a KeyValuePair object.
      //
      outputBlock.Text += String.Format(
          "\nContains(KeyValuePair(\"txt\", \"notepad.exe\")): {0}",
          openWith.Contains(new KeyValuePair<String, String>("txt", "notepad.exe"))) + "\n";

      // The Remove method takes a KeyValuePair object.)
      //
      // Use the Remove method to remove a key/value pair.
      outputBlock.Text += String.Format("\nRemove(new KeyValuePair(\"dib\", \"paint.exe\"))") + "\n";
      openWith.Remove(new KeyValuePair<String, String>("dib", "paint.exe"));

      outputBlock.Text += "\n";
      foreach (KeyValuePair<string, string> element in openWith)
      {
         outputBlock.Text += String.Format("{0}, {1}", element.Key, element.Value) + "\n";
      }

      // Create an array of KeyValuePair objects and copy the 
      // contents of the dictionary to it. 
      // 
      KeyValuePair<string, string>[] copy =
          new KeyValuePair<string, string>[openWith.Count];
      openWith.CopyTo(copy, 0);

      // List the contents of the array.
      //
      outputBlock.Text += "\n";
      foreach (KeyValuePair<string, string> element in copy)
      {
         outputBlock.Text += String.Format("{0}, {1}", element.Key, element.Value) + "\n";
      }
   }
}

/* 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
 */

Version Information

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Platforms

Windows Phone

See Also

Reference

Dictionary<(Of <(TKey, TValue>)>) Class

System.Collections.Generic Namespace