KeyedCollection<TKey, TItem> Constructor

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Initializes a new instance of the KeyedCollection<TKey, TItem> class that uses the default equality comparer.

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

Syntax

'Declaration
Protected Sub New

protected KeyedCollection()

A KeyedCollection<TKey, TItem> created with this constructor uses the default generic equality comparer for the type of the key, obtained from EqualityComparer<T>.Default. To specify a different generic equality comparer, use the KeyedCollection<TKey, TItem>(IEqualityComparer<TKey>) constructor or the KeyedCollection<TKey, TItem>(IEqualityComparer<TKey>, Int32) constructor.

By default, the KeyedCollection<TKey, TItem> includes a lookup dictionary that is created when the first item is added. When an item is added to the KeyedCollection<TKey, TItem>, the item's key is extracted once and saved in the lookup dictionary for faster searches. This behavior can be overridden by using the KeyedCollection<TKey, TItem>(IEqualityComparer<TKey>, Int32) constructor and specifying a dictionary creation threshold.

Note:
Because the KeyedCollection<TKey, TItem> class is abstract (MustInherit in Visual Basic), you must derive from it in order to use it. In the constructor for your derived type, call the appropriate KeyedCollection<TKey, TItem> constructor. It is not necessary to expose functionality like the equality comparer or the dictionary creation threshold in your constructors.

This constructor is an O(1) operation.

Supported in: 5, 4, 3

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.