ABAP Exceptions

Exception handling in ABAP is crucial for developing robust programs that can gracefully handle errors and unexpected conditions. This guide covers the basics of exceptions in ABAP, including how to define, raise, and handle exceptions.

Types of Exceptions

1. System Exceptions

System exceptions are predefined exceptions raised by the ABAP runtime environment during the execution of a program.

  • Examples of system exceptions:
    • SY-SUBRC: System return code after an operation.
    • SY-DBCNT: Number of records processed by a database operation.

2. User-Defined Exceptions

User-defined exceptions are explicitly raised by the programmer within a program using the RAISE statement.

  • Syntax: 
    RAISE exception_name.

Handling Exceptions

Using TRY...ENDTRY Block

The TRY...ENDTRY block is used to handle exceptions in ABAP. Code that might raise an exception is placed inside the TRY block, and the exception handling code is placed in the CATCH block.

  • Basic Syntax:

    TRY.
    " Code that might raise an exception
CATCH cx_exception_class.
    " Code to handle the exception
ENDTRY.

  • Example:

    DATA: lv_num TYPE I VALUE 0,
      lv_result TYPE I.

TRY.
    lv_result = 10 / lv_num.
CATCH cx_sy_arithmetical_error.
    WRITE: / 'Division by zero error'.
ENDTRY.

Using CLEANUP Block

The CLEANUP block is used to release resources or perform cleanup actions regardless of whether an exception occurred or not.

  • Syntax: 
    TRY.
    " Code that might raise an exception
CATCH cx_exception_class.
    " Code to handle the exception
CLEANUP.
    " Code to clean up resources
ENDTRY.

RAISE EXCEPTION

The RAISE EXCEPTION statement is used to explicitly raise an exception within a TRY block. This is often used in methods or function modules.

  • Syntax:

    RAISE EXCEPTION TYPE cx_exception_class.

  • Example:

    IF lv_num = 0.
    RAISE EXCEPTION TYPE cx_sy_arithmetical_error.
ENDIF.

Predefined Exception Classes

ABAP provides several predefined exception classes that cover common errors. These can be used directly or extended for custom error handling.

  • Common Exception Classes:

    • CX_SY_ARITHMETICAL_ERROR: Raised for arithmetic errors.
    • CX_SY_ZERODIVIDE: Raised when division by zero is attempted.
    • CX_SY_CONVERSION_NO_NUMBER: Raised when a non-numeric value is converted to a number.
    • CX_SY_FILE_OPEN_MODE: Raised when a file cannot be opened.

  • Example:

    TRY.
    lv_result = 10 / lv_num.
CATCH cx_sy_zerodivide.
    WRITE: / 'Cannot divide by zero'.
ENDTRY.

Custom Exception Classes

You can define your own exception classes by inheriting from the CX_ROOT class or one of its subclasses.

  • Defining a Custom Exception:

    CLASS cx_custom_exception DEFINITION INHERITING FROM cx_static_check.
ENDCLASS.

CLASS cx_custom_exception IMPLEMENTATION.
ENDCLASS.

  • Raising a Custom Exception:

    RAISE EXCEPTION TYPE cx_custom_exception.

  • Handling a Custom Exception:

    TRY.
    " Code that might raise the custom exception
CATCH cx_custom_exception.
    WRITE: / 'Custom exception occurred'.
ENDTRY.

Example Program with Exception Handling

REPORT z_exception_example.

DATA: lv_num TYPE I VALUE 0,
      lv_result TYPE I.

TRY.
    IF lv_num = 0.
        RAISE EXCEPTION TYPE cx_sy_zerodivide.
    ENDIF.

    lv_result = 10 / lv_num.
    WRITE: / 'Result:', lv_result.

CATCH cx_sy_zerodivide.
    WRITE: / 'Error: Division by zero is not allowed.'.

CLEANUP.
    WRITE: / 'Cleanup actions if any.'.
ENDTRY.

Conclusion

Exception handling is an essential aspect of ABAP programming. By using exceptions effectively, you can ensure that your programs handle errors gracefully and maintain stability even in unexpected conditions. This guide provides an overview, but for complex scenarios, refer to SAP documentation or additional resources.