Let's learn ABAP OO Objects

Global class & Exception Class Creation

Transaction: SE24

Through this transaction code, we can able to create a global class. Basically global class are created for the use of reusability. If reusability is not not required, then we can create a local class. 

Lets class name starts with YCL_ or ZCL

Provide a description for the class and make as usual ABAP Class with Public.

Final methods cannot be redefined in subclasses. Final classes cannot have any more subclasses and constitute the final node of an inheritance tree.

Lets create a sample program using this global class, for this purpose we have created an attribute and few methods with an exception class. 

Properties Tab

Attributes Tab

Here, I have created an attribute (A_SFLIGHT), which can used for all the methods in the same class.

Methods Tab

Here I have created a CONSTRUCTOR method, Constructors are special methods that cannot be called using CALL METHOD. Instead, they are called automatically by the system to set the initial state of a new object or class. There are two types of constructors - instance constructors and static constructors. Constructors are methods with a predefined name.

The system calls the instance constructor once for each instance of the class, directly after the object has been created in the CREATE OBJECTstatement. You can pass the input parameters of the instance constructor and handle its exceptions using the EXPORTING and EXCEPTIONS additions in the CREATE OBJECT statement.

The static constructor of a class is the predefined static method CLASS_CONSTRUCTOR.

The static constructor has no parameters. The system calls the static constructor once for each class, before the class is accessed for the first time. The static constructor cannot therefore access the components of its own class.

In constructor method

In above mentioned code, I have used the exception class. Creation of Exception class are explained finally.

Method VALIDATE_SFLIGHT

Method COST_OF_FLIGHT

Usage of global class in a report program

*---* Reference Object...

     DATA : lr_object     TYPE REF TO ycl_sample_class_01,
                lr_exception TYPE REF TO ycx_exec_sample.

    *---* Structure...

     DATA : x_sflight      TYPE sflight.

    *---* Variable Declaration...

     DATA : v_error       TYPE string,
                v_price       TYPE s_price,
                v_curre       TYPE s_currcode.

     START-OF-SELECTION.

     TRY.

      CREATE OBJECT lr_object " Constructor
        EXPORTING
          carrid = 'AB'
          connid = '17'
          fldate = '20130828'.

      lr_object->validate_sflight( IMPORTING sflight = x_sflight ). " Validate the sflight entry

      lr_object->cost_of_flight(    " Cost of the flight ticket
      IMPORTING
        price     = v_price
        currency  = v_curre ).

    CATCH ycx_exec_sample INTO lr_exception.
      v_error = lr_exception->if_message~get_text( ).
      WRITE v_error.
    

    ENDTRY.

    END-OF-SELECTION.

    WRITE : / 'Carrid :',   x_sflight-carrid.
    WRITE : / 'Price :',    v_price.
    WRITE : / 'Currency :', v_curre.
    WRITE : / v_error.

Exception Class

Again use the Transaction code SE24 for creating a exception class 

Let class name starts with YCX_ or ZCX

Follow the same procedure as per the below mentioned screenshot, to create the same. 

In ATTRIBUTES Tab, I have added a attribute 'CARRID', to get the CARRID value while exception is raised.

In TEXT Tab, add the custom text messsage to get displayed while exception is raised.

Use this exception class, In the constructor method of YCL_SAMPLE_CLASS_01 class.

Lets see the output

With correct CARRID Value

With Incorrect CARRID Value