How To Fix OO305 - Parameter &1 &2 &3: Only IMPORTING / CHANGING parameters can be optional

SAP Error Message - Details

• Message type: E = Error

• Message class: OO - Class Builder/API

• Message number: 305

• Message text: Parameter &1 &2 &3: Only IMPORTING / CHANGING parameters can be optional

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message OO305 - Parameter &1 &2 &3: Only IMPORTING / CHANGING parameters can be optional ?

  The SAP error message OO305 indicates that there is an issue with the parameters defined in a method of a class or an interface. Specifically, it states that only IMPORTING or CHANGING parameters can be optional, and it typically occurs when you try to define a parameter as optional that is not of the correct type (i.e., it is not an IMPORTING or CHANGING parameter).
  Cause:
  The error arises when:
  
  You have defined a parameter in a method as optional, but it is not an IMPORTING or CHANGING parameter.
  The method signature is incorrectly defined, possibly due to a misunderstanding of how optional parameters work in ABAP Object-Oriented programming.
  
  Solution:
  To resolve this error, you should:
  
  
  Check the Method Definition: Review the method signature in the class or interface where the error occurs. Ensure that only IMPORTING or CHANGING parameters are marked as optional.
  
  
  Modify Parameter Types: If you have a parameter that is defined as EXPORTING or RETURNING and you want it to be optional, you need to change its type to IMPORTING or CHANGING. 
  
  
  Remove Optional Flag: If the parameter does not need to be optional, you can simply remove the optional flag from the parameter definition.
  
  
  Example:
  Here’s a simple example to illustrate the correct usage:
  CLASS my_class DEFINITION.
    PUBLIC SECTION.
      METHODS my_method
        IMPORTING
          VALUE(param1) TYPE string OPTIONAL
        CHANGING
          VALUE(param2) TYPE string OPTIONAL
        EXPORTING
          VALUE(param3) TYPE string.  " This will cause OO305 error
  ENDCLASS.
  
  CLASS my_class IMPLEMENTATION.
    METHOD my_method.
      " Method implementation
    ENDMETHOD.
  ENDCLASS.
  In the above example, param3 is defined as EXPORTING and is incorrectly marked as optional. To fix this, you can either remove the OPTIONAL keyword or change the parameter type to IMPORTING or CHANGING.
  Related Information:
  
  ABAP Documentation: Refer to the official SAP ABAP documentation for more details on method parameter types and their usage.
  SAP Community: You can find discussions and solutions related to similar issues on the SAP Community forums.
  Debugging: If you encounter this error during runtime, use the ABAP debugger to trace back to the method call and check the parameters being passed.
  
  By following these guidelines, you should be able to resolve the OO305 error effectively.