Error in simple oops program

Question

Hi experts,
When executing a simple oops program ..i got the following error. Please correct the code.
"VAR" is not type-compatible with formal parameter "I_DATA".          
      CLASS main DEFINITION
CLASS main DEFINITION.
  PUBLIC SECTION.
    "// Instance Methods ( Note we use the statement 'METHODS'
    "// to define an instance method )
    METHODS set_data IMPORTING i_data TYPE string.
    METHODS get_data RETURNING value(r_data) TYPE string.
    METHODS print_attribute IMPORTING i_data TYPE string.
    "// Instance Methods ( Note we use the statement 'CLASS-METHODS'
    "// to define a static method )
    CLASS-METHODS set_classdata IMPORTING i_data TYPE string.
    CLASS-METHODS get_classdata RETURNING value(r_data) TYPE string.
    CLASS-METHODS print_classattribute IMPORTING i_data TYPE string.
  PROTECTED SECTION.
    "// Instance Attribute ( Note we use the statement 'DATA'
    "// to define an instance attribute )
    DATA attribute TYPE string.
    "// Static Attribute ( Note we use the statement 'CLASS-DATA'
    "// to define a static attribute )
    CLASS-DATA classattribute TYPE string.
  PRIVATE SECTION.
    "// Instace event ( Note we use the statement 'EVENTS'
    "// to define aN instance event )
    EVENTS event EXPORTING value(e_data) TYPE string.
    "// Instace event ( Note we use the statement 'CLASS-EVENTS'
    "// to define a static event )
    CLASS-EVENTS classevent EXPORTING value(e_data) TYPE string.
    "// For more informations about events see the following example:
    "// ABAP Objects - Creating your First Local Class - Using Events
ENDCLASS.                    "main DEFINITION
      CLASS main IMPLEMENTATION
CLASS main IMPLEMENTATION.
  METHOD set_data.
    CONCATENATE 'Instance Attribute value' i_data
                               INTO attribute SEPARATED BY space.
  ENDMETHOD.                    "set_data
  METHOD get_data.
    MOVE attribute TO r_data.
  ENDMETHOD.                    "get_data
  METHOD set_classdata.
    CONCATENATE 'Static Attribute value' i_data
                               INTO classattribute SEPARATED BY space.
  ENDMETHOD.                    "set_classdata
  METHOD get_classdata.
    MOVE main=>classattribute TO r_data.
  ENDMETHOD.                    "get_classdata
  METHOD print_attribute.
    WRITE: i_data, /.
  ENDMETHOD.                    "print_attribute
  METHOD print_classattribute.
    WRITE: i_data, /.
  ENDMETHOD.                    "print_classattribute
ENDCLASS.                    "main IMPLEMENTATION
DATA: var type char20.
START-OF-SELECTION.
  "// Calling a Static method (note we don't have a object )
  "// instead we use the <class name>=><method name>.
  main=>set_classdata( 'SDN' ).
  var = main=>get_classdata( ).
  "// Print the var value
  main=>print_classattribute( var ).
  DATA: object_reference TYPE REF TO main.
  CREATE OBJECT object_reference.
  "// - Calling a Instance Method( Note we have to use a object to
  "// access the insntace components of class main )
  "// - Note we're using the statment "CALL METHOD", see looking for
  "// functional & General methods for more informations
  CALL METHOD object_reference->set_data( 'BPX' ).
  var = object_reference->get_data(  ).
  object_reference->print_attribute( var ).
Thanks in Advance.
Regards
Nani

Answer 1

Hi Nani,
try changing your data definition for var from CHAR20 to STRING.
regards,
Peter