ABAP Keyword Documentation → ABAP - Reference → Declarative statemnts → Classes and Interfaces → ABAP Objects - Overview → Inheritance
Inheritance and Interfaces
Interfaces are independent constructs in ABAP Objects that support
polymorphism of classses.
The polymorphism of interfaces is based on the fact that each class implementing an interface can implement the methods of that interface differently. To the outside world, all interface components look similar which is why
interface reference
variables can point to objects of all classes that implement the associated interface. The interface
concept exists independently of and in addition to the inheritance concept.The classes of an inheritance
tree can implement any number of interfaces but each interface can be implemented only once in each
inheritance tree. This ensures that each interface component comp has a unique
name in the entire inheritance tree intf~icomp and that, starting with the class that implements it, it is contained in all subclasses.
Interface reference variables that can point to a class of the inheritance tree can also point to all subclasses. Having been implemented, interface methods are fully functioning components of a class and can be redefined in subclasses.