Simple Local Class

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Introduction:

  1. As a beginner, let us consider a short & simple example of a program using Object Oriented Concept.
  2. We will simply cover the following basic concepts: 
  • Define & Implement Class C. 
  • Create Visibility for the attributes of Class C.
  • Define & Implement Method M.
  • Create an Object for Class C.
  • Call a Method M for Class C.
Steps: 
  1. Create an executable program in SE 38. 
  • Program: ZOABAP_SIMPLEPROG.

      2. Define Class C.



  • Here we will create a Visibility for the attributes of the class as PUBLIC SECTION.
    • For parameters PART1, PART2, FULL.
    • For Method M.
  • Class Attribute Visibility
    • Public: 
      • All the components which are assigned to this section are public and can be accessed outside the class, methods of the subclass, and the methods of the class itself. 
      • They form the external interface of the class.
    •  Protected: 
      • The components of this section are protected and can be accessed by the methods of subclass and the methods of the class itself. 
      • They form the interface of the class and its subclass. 
    • Private: 
      • Components of this section are private and can only be used in the methods of the class itself. 
      • The private components are not part of the external interface of the class. 


       3. Create Implementation of Class C.



  • Here we will create Implementation for Method M.
  • We will create a simple scenario for 'CONCATENATE' and 'WRITE' as shown above. 

    4. Create an Object for Class C.
  • To call our Method M we have to create an Object for reference parameter OBJ of Class C.
  • Here method M is an 'INSTANT' Method.
  • Class Attributes
    • Instance Attributes: 
      • You declare them using the DATA statement. 
      • To access we need to create an Object.
      • Instance attributes are accessed using the Object Component Selector ‘->’.
    • Static Attributes: 
      • You declare them using the CLASS-DATA statement. 
      • To access we need not create an Object.
      • Static attributes are accessed using the Class Component Selector ‘=>’.  
   

     5. Now save, activate and execute the program.

 


Example Code:

REPORT  ZOABAP_SIMPLEPROG.
CLASS C DEFINITION.
  PUBLIC SECTION.
  DATA: PART1(5) TYPE C,
       PART2(5) TYPE C,
       FULL TYPE STRING.
  METHODS: M.
ENDCLASS.

CLASS C IMPLEMENTATION.
  METHOD M.
    PART1 = 'VIDYA'.
    PART2 = 'SAGAR'.
  WRITE: PART1 COLOR 3, /
        PART2 COLOR 4.
 CONCATENATE PART1 '' PART2 '' INTO FULL.
 WRITE:/ full COLOR 5.
 ENDMETHOD.
ENDCLASS.


 START-OF-SELECTION.
 DATA: OBJ TYPE REF TO C.
 CREATE OBJECT OBJ.
 CALL METHOD:
 OBJ->M.



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