How To Fix OO029 - Parameters/exceptions of inherited methods or events cannot be changed

SAP Error Message - Details

• Message type: E = Error

• Message class: OO - Class Builder/API

• Message number: 029

• Message text: Parameters/exceptions of inherited methods or events cannot be changed

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message OO029 - Parameters/exceptions of inherited methods or events cannot be changed ?

  The SAP error message OO029 indicates that there is an issue with the parameters or exceptions of inherited methods or events in an ABAP class. This typically occurs when you are trying to redefine a method in a subclass and you are attempting to change the signature (parameters or exceptions) of that method compared to its definition in the superclass.
  Cause:
  
  Method Redefinition: When you redefine a method in a subclass, the parameters (including their types) and exceptions must match exactly with those defined in the superclass. If there is any discrepancy, such as changing the type of a parameter or adding/removing exceptions, this error will occur.
  Inheritance Rules: In ABAP Object-Oriented programming, the rules of inheritance dictate that a subclass cannot alter the interface of a method that it inherits from a superclass.
  
  Solution:
  To resolve the OO029 error, you should ensure that the method signature in the subclass matches the method signature in the superclass exactly. Here are the steps to follow:
  
  Check Method Signature: Go to the superclass and check the method signature (parameters and exceptions) of the method you are trying to redefine.
  Match Parameters: Ensure that the parameters in the subclass method match the types, order, and number of parameters in the superclass method.
  Match Exceptions: Ensure that any exceptions declared in the superclass method are also declared in the subclass method without any changes.
  Re-implement Method: If you need to change the behavior of the method, you can implement the method in the subclass without changing its signature. You can call the superclass method within the subclass method if needed.
  
  Related Information:
  
  ABAP Documentation: Refer to the official SAP documentation on ABAP Object-Oriented programming for more details on method overriding and inheritance rules.
  ABAP Workbench: Use the ABAP Workbench (SE80) to navigate through the class definitions and check method signatures.
  Debugging: If you are unsure where the mismatch is occurring, you can use debugging tools to step through the code and identify the exact point of failure.
  
  By following these guidelines, you should be able to resolve the OO029 error and ensure that your class definitions adhere to the rules of inheritance in ABAP.