The reason for writing this post is to provide an overview of how interfaces and OOP concepts can be used in SAP ABAP. Many beginner-level developers working with SAP ABAP may have experience with procedural programming. They may need to be more familiar with OOP concepts like interfaces. By providing a clear explanation of interfaces and how they support OOP programming, readers can better understand how to design and implement modular and maintainable code in SAP ABAP.

SAP ABAP is an object-oriented programming language that supports many OOP concepts, including encapsulation, inheritance, and polymorphism. The Interface is one of the critical tools for implementing these concepts in SAP ABAP.

In this blog post, we’ll explore the use of interfaces in SAP ABAP and how they support OOP programming.

In reading this blog, I hope readers can learn:

1. What an interface is and why it’s important in OOP programming.
2. How interfaces are defined and implemented in SAP ABAP.
3. Applying interfaces in SAP ABAP can provide standardization, flexibility, modularity, polymorphism, and testability to your code.
4. How to design and implement modular and maintainable code using interfaces and OOP concepts in SAP ABAP.

What is an Interface?

In OOP programming, an interface is a blueprint or a contract that defines a set of methods that a class must implement. It provides a standard way to define the behaviour of a group of related classes.

Why Use Interfaces in SAP ABAP?

Interfaces are used in SAP ABAP for several reasons, including:

1. Standardization: Interfaces provide a standard way to define methods that can be used across different classes. This standardization helps to ensure consistency and makes it easier to maintain the code.
2. Flexibility: Interfaces allow you to define a set of methods that a class must implement, but they don’t dictate how those methods are implemented. This means you can use different implementations for the same Interface, which gives you more flexibility in designing your code.
3. Modularity: Interfaces help to modularize your code by separating the definition of a method from its implementation. This makes it easier to update or replace the implementation of a method without affecting other parts of the code.
4. Polymorphism: The term polymorphism literally means ‘many forms’. Using interfaces, you can allow multiple classes to implement a service differently but using the same.

What is the difference between an Abstract Class vs an Interface?

• Multiple Inheritance:
  We can achieve multiple inheritances using Interfaces. Since ABAP doesn’t support more than one Super class, we can have only one abstract class as a Superclass.
• New Functionality:
  If we add a new method in the Interface, all the implementing classes must implement this method. If we don’t implement the method, it will result in a Run-time error. For the Abstract category, if we add a non-abstract way, it’s not required to redefine that in each and every inherited class.
• Default Behavior:
  We can have a default behaviour of a non-abstract method in an abstract class. We can’t have any implementation in Interface as it only contains the empty stub.
• Visibility:
  All interface components are PUBLIC by default. For the Abstract class, we can set the visibility of each element.

How to Define an Interface in SAP ABAP?

• In the Repository Browser (transaction SE80), navigate to the package where you want to create an interface.
• In the context menu of the package, choose to Create → Class Library → Interface.
  The Create Interface dialog box appears.or
• You can directly go to the SE24.
• Enter the new class’s name according to the naming conventions. The name of the interface should begin with IF_.
  Example:- ZIF_.
• In the Description field, enter a short description of the interface.
• Choose Save.
  

  Summary

  In summary, developers can write more modular, flexible, and maintainable code by leveraging OOP concepts like interfaces in SAP ABAP. By standardizing method definitions across different classes, interfaces can make it easier to maintain code and ensure consistency. Interfaces can also promote flexibility, modularity, and polymorphism and make it easier to test your code.
  In my next blog post, I will explore more complex examples of how interfaces and abstract classes can be used in everyday scenarios.

  You can find more details on the following links:
  ABAP Topics – SAP Community
  Interfaces – Documentation