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Dictionary.KeyCollection Generic Class

Represents the collection of keys in a Dictionary. This class cannot be inherited.

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

public sealed class KeyCollection : ICollection<TKey>, IEnumerable<TKey>, 
	ICollection, IEnumerable
J# supports the use of generic types and methods, but not the declaration of new ones.
JScript does not support generic types and methods.
Not applicable.

The Dictionary.Keys property returns an instance of this type, containing all the keys in that Dictionary. The order of the keys in the Dictionary.KeyCollection is unspecified, but it is the same order as the associated values in the Dictionary.ValueCollection returned by the Dictionary.Values property.

The Dictionary.KeyCollection is not a static copy; instead, the Dictionary.KeyCollection refers back to the keys in the original Dictionary. Therefore, changes to the Dictionary continue to be reflected in the Dictionary.KeyCollection.


Public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

A Dictionary.KeyCollection can support multiple readers concurrently, as long as the collection is not modified. Even so, enumerating through a collection is intrinsically not a thread-safe procedure. To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

.NET Compact Framework

Supported in: 2.0

XNA Framework

Supported in: 1.0