Treat invalid input as an explicit outcome

A parcel cannot be tracked without a tracking code. Returning a normal-looking summary for invalid input hides the problem. A class-based exception gives the method a way to report that it could not fulfill its contract.

Declare and raise a specific exception

CLASS lcx_missing_code DEFINITION INHERITING FROM cx_static_check.
ENDCLASS.

METHODS validate
  IMPORTING iv_code TYPE string
  RAISING lcx_missing_code.

METHOD validate.
  IF iv_code IS INITIAL.
    RAISE EXCEPTION TYPE lcx_missing_code.
  ENDIF.
ENDMETHOD.

cx_static_check is a checked-exception category. The method advertises the exception in RAISING, so callers must handle or propagate it according to the language rules. Other exception categories exist; choose based on whether callers should be required to handle the condition.

Catch at a useful boundary

TRY.
    validator->validate( iv_code = input_code ).
  CATCH lcx_missing_code.
    result = 'Tracking code is required'.
ENDTRY.

Catch the most specific exception you can handle. Do not catch everything merely to continue with invalid state; log, report, or recover in a way that makes the failure visible.

Practice

Create a checked exception type, raise it for an initial code, and handle that type in CATCH. Assign a clear message to result; then add environment output. This is structural practice, not a running exception test.

Version note: Exception class availability and allowed APIs are release/language-version dependent. The example uses a local exception class to avoid external dependencies.

Sources

• SAP Samples, ABAP Object Orientation: class-based exceptions
• SAP Help Portal, ABAP Objects overview

CLASS lcx_missing_code DEFINITION INHERITING FROM cx_static_check.
ENDCLASS.
CLASS lcl_validator DEFINITION.
  PUBLIC SECTION.
    METHODS validate IMPORTING iv_code TYPE string RAISING lcx_missing_code.
ENDCLASS.
CLASS lcl_validator IMPLEMENTATION.
  METHOD validate.
    IF iv_code IS INITIAL.
      RAISE EXCEPTION TYPE lcx_missing_code.
    ENDIF.
  ENDMETHOD.
ENDCLASS.
DATA(validator) = NEW lcl_validator( ).
TRY.
    validator->validate( iv_code = '' ).
    DATA(result) = 'Code accepted'.
  CATCH lcx_missing_code.
    result = 'Tracking code is required'.
ENDTRY.

WRITE result.

out->write( result ).