Chapter 6. Implementing Interfaces
An interface defines a protocol of behavior that can be implemented by any class anywhere in the class hierarchy. An interface defines a set of methods but does not implement them. A class that implements the interface agrees to implement all the methods defined in the interface, thereby agreeing to certain behavior.
Because an interface is simply a list of unimplemented methods you might wonder how an interface differs from an abstract class. The differences are significant:
An interface cannot implement any methods, whereas an abstract class can. A class can implement many interfaces but can have only one superclass. An interface is not part of the class hierarchy. Unrelated classes can implement the same interface.
Let's look at C# interfaces more closely.
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