How To Fix OO166 - Only import parameters are allowed with constructor methods

SAP Error Message - Details

• Message type: E = Error

• Message class: OO - Class Builder/API

• Message number: 166

• Message text: Only import parameters are allowed with constructor methods

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message OO166 - Only import parameters are allowed with constructor methods ?

  The SAP error message OO166 ("Only import parameters are allowed with constructor methods") typically occurs in ABAP when you are trying to define a constructor method in a class with parameters that are not allowed. In ABAP Object-Oriented Programming, constructor methods can only have import parameters. This means that you cannot use changing, exporting, or tables parameters in the constructor method.
  Cause:
  The error is caused by the following scenarios:
  
  You have defined a constructor method with parameters that are not of type "IMPORTING".
  You may have mistakenly included parameters that are meant to be "EXPORTING", "CHANGING", or "TABLES".
  
  Solution:
  To resolve this error, you need to ensure that all parameters in the constructor method are defined as import parameters. Here’s how you can do that:
  
  
  Check the Method Definition: Open the class definition where the constructor is defined and check the parameters.
  
  
  Modify the Parameters: Change any non-import parameters to import parameters. For example, if you have:
  METHOD constructor.
    IMPORTING
      !value1 TYPE string,
    CHANGING
      !value2 TYPE string.  " This will cause the error
  ENDMETHOD.
  You should modify it to:
  METHOD constructor.
    IMPORTING
      !value1 TYPE string.
  ENDMETHOD.
  
  
  Remove Non-Allowed Parameters: If you need to pass values that would typically require changing or exporting parameters, consider redesigning your class or using setter methods after the object is instantiated.
  
  
  Related Information:
  
  Constructor Method: In ABAP, a constructor method is a special method that is called when an instance of a class is created. It is used to initialize the object.
  Parameter Types: In ABAP, method parameters can be defined as IMPORTING, EXPORTING, CHANGING, or TABLES. However, only IMPORTING parameters are allowed in constructor methods.
  Best Practices: It is a good practice to keep constructor methods simple and only use them for initialization. If you need to perform more complex operations, consider using additional methods.
  
  By following these guidelines, you should be able to resolve the OO166 error and properly define your constructor methods in ABAP.