EqualityComparer Generic Class

Provides a base class for implementations of the IEqualityComparer generic interface.

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

public abstract class EqualityComparer<T> : IEqualityComparer, IEqualityComparer<T>
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.

Type Parameters


The type of objects to compare.

Derive from this class to provide a custom implementation of the IEqualityComparer generic interface for use with collection classes such as the Dictionary generic class, or with methods such as List.Sort.

The Default property checks whether type T implements the System.IEquatable generic interface and if so returns an EqualityComparer that uses that implementation. Otherwise it returns an EqualityComparer that uses the overrides of Object.Equals and Object.GetHashCode provided by T.


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

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, 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

Community Additions