Mastering SAP ABAP Interfaces: From Definition to Implementation

 

Interfaces in SAP ABAP :-

• Interfaces provide a standard way to define methods that can be used across different classes.
• In Interface all methods are public by default.
• In Interface all methods are abstract methods ( i.e. There is only definition, no implementation ).

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Difference between Abstract Classes and Interfaces :-

1. Abstract Class :-

• In Abstract class, we have at least one abstract method, others can be non-abstract methods.
• Methods visibility can be Public, Private and Protected.
• We need to redefine the abstract method in to sub classes to perform the implementation in Sub class
• Multiple Inheritance is not possible.

Important Point :-

• We can not redefine a static method.

2. Interfaces :-

• All methods are abstract methods in Interface.
• All methods are public.
• There is no need to click on the redefine button ( redefine button is disabled ), we can write the logic in class by double.
• Multiple Inheritance is possible.

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• let’s take a requirement, where we create a interface with one method and then, we will implement that Interface in another class.
• Our requirement is to display Sales Order Details from VBAK table on the basis of Sales Document Number.

How to create a Interface in Usual ABAP / Global Class (SE24 ) ?

• Step 1 :- Go to SE24 transaction code.

• Step 2 :- Give a name to the interface and click on create button.

  
  
  

  
  

• Step 3 :- A popup screen will appear, select the Interface radio button.

  
  
  

  
  

  • Press Enter.

• Step 4 :- Provide a description for the interface.

  
  
  

  
  

• Step 5 :- Our Interface Screen will appear.

  
  
  

  
  

• Step 6 :- Here we will give the name of our method.

  • Note :- You can see in the above diagram that Visibility option is not present in case of Interface.
  
  
  

  
  

  • Click on Parameters and provide the importing and exporting parameters.

    
    
    

    
    

  • Save and activate the interface.

    
    
    
    

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• Step 7 :- Now, we need to implement the Interface in a class, So create a class from SE24 transaction code.

  
  
  

  
  

• Step 8 :- click on create button and select Class radio button.

  
  
  

  
  

  • Press enter.
  
  
  

  
  

• Step 9 :- Select the Interface tab.

  
  
  

  
  

• Step 10 :- Fill the details as shown below.

  
  
  

  
  

  • Now click on Methods tab, you can see that the Method of interface is already assigned here.
  
  
  

  
  

• Step 11 :- Click on source code and write the logic.

  
  
  

  
  

  • Activate the class.

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Execute the Class :-

• Press F8 to execute the class.

  
  
  

  
  

• Press F8.

  
  
  

  
  

  • You can see it, is perfectly working.

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Let’s achieve the above same to same requirement using local classes and Interfaces through ABAP Editor ( SE38 ).

Implementing Interface Using Program in ABAP :-

Code :-

*&---------------------------------------------------------------------*
*& Report ZAR_INTERFACE_IMPLEMENT
*&---------------------------------------------------------------------*
*&
*&---------------------------------------------------------------------*
REPORT ZAR_INTERFACE_IMPLEMENT.

DATA : perdat type erdat,
       perzet type erzet,
       pernam type ernam,
       pvbtyp type vbtypl.

PARAMETERS : p_vbeln type vbeln_va.

INTERFACE Sales_Order.
  METHODS DISPLAY IMPORTING pvbeln type vbeln_va
                  EXPORTING perdat type erdat
                            perzet type erzet
                            pernam type ernam
                            pvbtyp type vbtypl.

ENDINTERFACE.

CLASS Sales_Order_IMPLEMENTATION DEFINITION.
  PUBLIC SECTION.
  INTERFACES Sales_Order.

ENDCLASS.

CLASS Sales_Order_IMPLEMENTATION IMPLEMENTATION.
  Method Sales_Order~DISPLAY.
    SELECT single erdat erzet ernam vbtyp
      from vbak into ( perdat, perzet, pernam, pvbtyp ).
  ENDMETHOD.
ENDCLASS.

START-OF-SELECTION.
DATA(lo_object) = new Sales_Order_IMPLEMENTATION( ).
lo_object->Sales_Order~DISPLAY( EXPORTING pvbeln = p_vbeln
                                IMPORTING perdat = perdat
                                          perzet = perzet
                                          pernam = pernam
                                          pvbtyp = pvbtyp ).

WRITE :/ perdat, perzet, pernam, pvbtyp.

*&------------------------------------------------------------------------
*&End of Program
*&--------------------------------------------------------------

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Execute the Code :-

• Press F8.