我正在尝试运行从教程复制的这个程序。
但我在这一行得到 Null 异常
CALL METHOD list->SET_TABLE_FOR_FIRST_DISPLAY.
我的理解是列表对象应该在类构造函数中创建。
Method CLASS_CONTRUCTOR.
CREATE OBJECT list
EXPORTING
i_parent = cl_gui_container=>screen0.
ENDMETHOD.
//代码
请看一看。
class select_display_sflight DEFINITION.
public section.
CLASS-METHODS class_contructor.
Methods: constructor
importing i_carrid type sflight-carrid
i_connid type sflight-connid
Exceptions nothing_found,
display_sflight.
private section.
CLASS-DATA list type ref to CL_GUI_ALV_GRID.
data sflight_tab TYPE TABLE OF sflight.
ENDCLASS.
class select_display_sflight IMPLEMENTATION.
Method CLASS_CONTRUCTOR.
CREATE OBJECT list
EXPORTING
i_parent = cl_gui_container=>screen0.
ENDMETHOD.
Method CONSTRUCTOR.
select * from sflight
into table sflight_tab
where carrid = i_carrid and
connid = i_connid.
if sy-subrc = 4 .
raise NOTHING_FOUND.
ENDIF.
ENDMETHOD.
Method display_sflight.
CALL METHOD list->SET_TABLE_FOR_FIRST_DISPLAY
EXPORTING
i_structure_name = 'SFLIGHT'
CHANGING
it_outtab = sflight_tab.
call screen 100.
ENDMETHOD.
ENDCLASS.
Selection-SCREEN begin of screen 500.
parameters: p_carrid type sflight-carrid,
p_connid type sflight-connid.
selection-screen end of screen 500.
data: begin of ref_tab_line,
carrid type sflight-carrid,
connid type sflight-connid,
oref type ref to select_display_sflight,
end of ref_tab_line,
ref_tab like sorted table of ref_tab_line
with unique key carrid connid.
START-OF-SELECTION.
do.
call SELECTION-SCREEN 500 starting at 10 10.
if sy-subrc <> 0.
leave program.
endif.
ref_tab_line-carrid = p_carrid.
ref_tab_line-connid = p_connid.
read table ref_tab into ref_tab_line
from ref_tab_line.
if sy-subrc <> 0.
CREATE OBJECT ref_tab_line-oref
EXPORTING
i_carrid = p_carrid
i_connid = p_connid
EXCEPTIONS
nothing_found = 4.
IF sy-subrc = 4.
Message i888(sabapdocu) with 'No data'.
CONTINUE.
else.
insert ref_tab_line into table ref_tab.
ENDIF.
endif.
CALL METHOD ref_tab_line-oref->display_sflight.
ENDDO.
您犯了一个错字。你把信吃了S in the CLASS_CONSTRUCTOR name.
It is:
CLASS-METHODS class_contructor.
Method CLASS_CONTRUCTOR.
应该：
CLASS-METHODS class_constructor.
Method CLASS_CONSTRUCTOR.
因此，静态构造函数永远不会被调用，因此list没有被初始化。
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