How To Fix OO109 - Class & is final - it cannot have subclasses

SAP Error Message - Details

• Message type: E = Error

• Message class: OO - Class Builder/API

• Message number: 109

• Message text: Class & is final - it cannot have subclasses

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message OO109 - Class & is final - it cannot have subclasses ?

  The SAP error message OO109 indicates that you are trying to create a subclass of a class that has been declared as "final." In object-oriented programming, a final class is one that cannot be subclassed. This is a design choice made to prevent further inheritance, often to maintain the integrity of the class's implementation or to prevent misuse.
  Cause:
  
  Final Class Declaration: The class you are trying to subclass has been declared as final. This means that it is intended to be used as is, without any further derivation.
  Inheritance Attempt: You are attempting to create a new class that extends this final class, which is not allowed.
  
  Solution:
  
  Check Class Declaration: Review the class definition of the class you are trying to subclass. If it is indeed declared as final, you will need to reconsider your design.
  Use Composition Instead: Instead of subclassing, consider using composition. This means you can create a new class that contains an instance of the final class rather than extending it.
  Refactor Your Design: If you have control over the final class and it makes sense to allow subclassing, you can remove the final keyword from the class declaration. However, this should be done with caution, as it may affect the intended design and functionality.
  Alternative Implementations: If the final class provides certain functionalities that you need, look for alternative classes or interfaces that can be used to achieve your goals without subclassing the final class.
  
  Related Information:
  
  Final Classes in SAP ABAP: In ABAP, a class can be declared as final using the FINAL keyword. This is a common practice to prevent further inheritance.
  Design Patterns: Understanding design patterns such as Strategy or Decorator can help you find ways to achieve your goals without needing to subclass final classes.
  Documentation: Always refer to the official SAP documentation for best practices regarding class design and inheritance in ABAP.
  
  By following these steps, you should be able to resolve the OO109 error and adjust your implementation accordingly.