Question

Why are there two overloads of Equals in .NET’s object class? If I want to have a custom equality function, e.g. so that I can use sets or dictionaries, should I override both (in addition to GetHashCode), or it is enough to override just one of them.

Answer 1

You can’t override the static version.

The reason for the static version is so that you can call object.Equals(myObject, myOtherObject) without checking for nulls beforehand.

Internally, it just checks for nulls (returning true if both objects are null), then delegates to myObject.Equals(myOtherObject). So overriding the non-static Equals method is all you need.