IDictionary.Add Method

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

Adds an element with the provided key and value to the IDictionary object.

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

Sub Add ( _
	key As Object, _
	value As Object _


Type: System.Object
The Object to use as the key of the element to add.
Type: System.Object
The Object to use as the value of the element to add.


key is Nothing.


An element with the same key already exists in the IDictionary object.


The IDictionary is read-only.


The IDictionary has a fixed size.

You can also use the Item property to add new elements by setting the value of a key that does not exist in the dictionary (for example, myCollection["myNonexistentKey"] = myValue). However, if the specified key already exists in the dictionary, setting the Item property overwrites the old value. In contrast, the Add method does not modify existing elements.

Implementations can vary in whether they allow the key to be Nothing.

The following code example demonstrates how to implement the Add method. This code example is part of a larger example provided for the IDictionary class.

Public Sub Add(ByVal key As Object, ByVal value As Object) Implements IDictionary.Add

   ' Add the new key/value pair even if this key already exists in the dictionary.
   If ItemsInUse = items.Length Then
      Throw New InvalidOperationException("The dictionary cannot hold any more items.")
   End If
   items(ItemsInUse) = New DictionaryEntry(key, value)
   ItemsInUse = ItemsInUse + 1
End Sub

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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