Item Property

SortedDictionary(Of TKey, TValue).Item Property

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

Gets or sets the value associated with the specified key.

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

'Declaration
Public Property Item ( _
	key As TKey _
) As TValue

Parameters

key
Type: TKey
The key of the value to get or set.

Property Value

Type: TValue
The value associated with the specified key. If the specified key is not found, a get operation throws a KeyNotFoundException, and a set operation creates a new element with the specified key.

Implements

IDictionary(Of TKey, TValue).Item(TKey)

ExceptionCondition
ArgumentNullException

key is Nothing.

KeyNotFoundException

The property is retrieved and key does not exist in the collection.

This property provides the ability to access a specific element in the collection by using the following C# syntax: myCollection[key] (myCollection(key) in Visual Basic).

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

A key cannot be Nothing, but a value can be, if the value type TValue is a reference type.

The C# language uses the [d4f827fe-4710-410b-89b8-867dad44b8a3] keyword to define the indexers instead of implementing the Item property. Visual Basic implements Item as a default property, which provides the same indexing functionality.

Getting the value of this property is an O(log n) operation; setting the property is also an O(log n) operation.

The following code example uses the Item property (the indexer in C#) to retrieve values, demonstrating that a KeyNotFoundException is thrown when a requested key is not present, and showing that the value associated with a key can be replaced.

The example also shows how to use the TryGetValue method as a more efficient way to retrieve values if a program often must try key values that are not in the dictionary.

This code example is part of a larger example provided for the SortedDictionary(Of TKey, TValue) class.

Windows Phone OS

Supported in: 8.1, 8.0

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