Example: 

” First interface
INTERFACE if_flyable.
METHODS: fly.
ENDINTERFACE.

” Second interface
INTERFACE if_swimmable.
METHODS: swim.
ENDINTERFACE.

” A class implementing multiple interfaces
CLASS cl_duck DEFINITION.
PUBLIC SECTION.
INTERFACES: if_flyable,
if_swimmable.
METHODS: display.
ENDCLASS.

CLASS cl_duck IMPLEMENTATION.
METHOD if_flyable~fly.
WRITE: / ‘The duck is flying.’.
ENDMETHOD.

METHOD if_swimmable~swim.
WRITE: / ‘The duck is swimming.’.
ENDMETHOD.

METHOD display.
WRITE: / ‘I am a duck with multiple abilities!’.
ENDMETHOD.
ENDCLASS.

START-OF-SELECTION.
DATA(duck) = NEW cl_duck( ).

duck->display( ).
duck->if_flyable~fly( ).
duck->if_swimmable~swim( ).

Output:

I am a duck with multiple abilities!
The duck is flying.
The duck is swimming.

Key Points:

• CLASS … DEFINITION uses INTERFACES: to include multiple interfaces.

• Methods from interfaces must be implemented in the class.

• When calling interface methods, you can:

  • Use fully qualified names: object->if_interface~method( )

  • Or, if redefined explicitly as public methods, call them directly.

• This is the standard way to achieve “multiple inheritance” in ABAP.