KeyedCollection<TKey, TItem> Constructor (IEqualityComparer<TKey>)

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

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

protected KeyedCollection(
	IEqualityComparer<TKey> comparer
)

Parameters

comparer
Type: System.Collections.Generic.IEqualityComparer<TKey>

The implementation of the IEqualityComparer<T> generic interface to use when comparing keys, or null to use the default equality comparer for the type of the key, obtained from EqualityComparer<T>.Default.

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.

NoteNote

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.

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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