Question

ALV输出的报表，在输出后返回的时候报错

A new value is to be assigned to the field "<L_BOX>", although this field is
entirely or partly protected against changes.

The following are protected against changes:
- Character literals or numeric literals
- Constants (CONSTANTS)
- Parameters of the category IMPORTING REFERENCE for functions and
methods
- Untyped field symbols not yet assigned a field using ASSIGN
- TABLES parameters if the actual parameter is protected against changes
- USING reference parameters and CHANGING parameters for FORMs, if the
actual parameter is protected against changes and
- Accesses using field symbols if the field assigned using ASSIGN is
protected (or partially protected, e.g. key components of an internal
table with the type SORTED or HASHED TABLE) against changes
- Accesses using references, if the field bound to the reference is
protected (or partially protected) against changes
- External write accesses to READ-ONLY attributes,
- Content of a shared object area instance accessed using a shared lock
(ATTACH_FOR_READ).
CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY'
EXPORTING
i_interface_check = 'X'
i_callback_program = sy-repid
is_layout = t_layout
it_fieldcat = i_fieldcat
TABLES
t_outtab = i_tab

Answer 1

其本都算输入项目，常用的是I_CALLBACK_PROGRAM 这个指返回的调用程序一般用SY-CPROG 和I_CALLBACK_USER_COMMAND（当前用户命令返回）这个参数 结合作为alv输出界面响应鼠标事件。I_CALLBACK_TOP_OF_PAGE = I_CALLBACK_HTML_TOP_OF_PAGE = ' '
I_CALLBACK_HTML_END_OF_LIST 顾名思义都是控制输出的alv表页面上方下方一些类似主题注释的显示。I_STRUCTURE_NAME 参数可以让你没有指定输出列结构时候参考某个透明表之类，输出的就是这个表的列，用的不多。IS_LAYOUT 输出的行控制例如颜色，设置成斑马线之类。IT_FIELDCAT 输出具体列，IT_SORT 排序方式 T_OUTTAB 输出取数的内表。其他的IS_VARIANT IT_EVENTS等等变式 事件之类在实际alv应用当中用的不多，如果想用一些复杂方法建议用oo调用输出

Answer 2

在输出后返回的时候报错
是输出后点返回报错？
ALV 输出后你又做了什么动作？