Building Applications and Components with Visual Basic .NET

Interfaces

An interface is a type that defines a programming contract—nothing more. You can think of an interface as an abstract class that consists purely of abstract members. This definition implies that an interface defines the calling signatures for a set of methods and properties, and that it never contains any form of implementation.

Let's begin our exploration of interfaces by comparing them to concrete base classes and abstract base classes. Recall that a concrete base class is a type that defines a programming contract along with a complete implementation, and an abstract base class is a type that defines a programming contract along with a partially completed implementation. An interface is a type that defines a programming contract ...