Final answer:
Overriding a method in an interface involves matching the method signature with the interface's declaration and returning either the same type or a subtype. Covariant return types allow the return of more specific types in a subclass, enhancing code flexibility.
Step-by-step explanation:
When a class implements an interface, it must provide concrete implementations of all the methods declared within that interface. The concept of overriding methods defined in interfaces entails providing a specific method behavior in a class that implements the interface.
Importantly, when overriding a method, the signature of the method in the class should match the signature as declared in the interface. This includes the method name and the parameter list.
The return type of the overridden method in the implementing class can either be the same as that specified in the interface or a subtype of it. This concept is known as covariant return types. By utilizing covariant return types, a more specific return type can be provided in the subclass, thereby enhancing the flexibility and reusability of the code.
Take, for example, an interface IAnimal with a method Sound that returns an object of type Sound. A class Dog that implements IAnimal can override the Sound method to return an object of a subclass of Sound, such as Bark, which would represent a more specific sound a dog makes.
It is important to note that the overriding method must preserve or lessen the visibility of the method, but never increase it. Consequently, if the method in the interface is public, the overriding method must also be public.