ABAP-CL_OBJECT_COLLECTION工具类

Title

ABAP-CL_OBJECT_COLLECTION

本文参考Jerry Wang的程序学习了使用abap来实现java中ArrayList的功能，参考文章SAP ABAP里存在Java List这种集合工具类么？CL_OBJECT_COLLECTION了解一下

一

代码

代码我是写在了本地，以便更容易看懂，主要用到了类接口和多态的思想，来避免重复造轮子。

REPORT ztest_polymorphism.

"定义接口

INTERFACE zif_shape. METHODS get_area RETURNING VALUE(rv_result) TYPE float. ENDINTERFACE. "定义计算圆面积 CLASS zcl_circle DEFINITION. PUBLIC SECTION. INTERFACES zif_shape. METHODS constructor IMPORTING !iv_radius TYPE float ."构造器，输入半径 PROTECTED SECTION. PRIVATE SECTION. DATA radius TYPE float . ENDCLASS. CLASS zcl_circle IMPLEMENTATION. METHOD constructor. me->radius = iv_radius. ENDMETHOD. METHOD zif_shape~get_area. CONSTANTS: pai TYPE float VALUE '3.14'. rv_result = pai * radius * radius. ENDMETHOD. ENDCLASS. "定义计算矩形面积 CLASS zcl_rectangle DEFINITION. PUBLIC SECTION. INTERFACES zif_shape. METHODS constructor IMPORTING !iv_height TYPE float !iv_width TYPE float . PROTECTED SECTION. PRIVATE SECTION. DATA height TYPE float . DATA width TYPE float . ENDCLASS. CLASS zcl_rectangle IMPLEMENTATION. METHOD constructor. height = iv_height. width = iv_width. ENDMETHOD. METHOD zif_shape~get_area. rv_result = width * height. ENDMETHOD. ENDCLASS. "定义计算三角形面积 CLASS zcl_triangle DEFINITION. PUBLIC SECTION. INTERFACES zif_shape. METHODS constructor IMPORTING !iv_side TYPE float !iv_height TYPE float . PROTECTED SECTION. PRIVATE SECTION. DATA side TYPE float . DATA height TYPE float . ENDCLASS. CLASS zcl_triangle IMPLEMENTATION. METHOD constructor. side = iv_side. height = iv_height. ENDMETHOD. METHOD zif_shape~get_area. rv_result = ( 1 / 2 ) * side * height. ENDMETHOD. ENDCLASS.

TYPES: BEGIN OF ty_shape, shape TYPE REF TO object, END OF ty_shape. TYPES: tt_shape TYPE STANDARD TABLE OF ty_shape. DATA: lt_shape TYPE tt_shape,"定义一个内表来存放不同的实例 lv_result TYPE float.

START-OF-SELECTION. "借助CL_OBJECT_COLLECTION, 采取面向对象编程里多态(Polymorphism)的思路 DATA(lo_container) = NEW cl_object_collection( ). DATA(lo_circle) = NEW zcl_circle( 1 ). lo_container->add( lo_circle )." DATA(lo_rectangle) = NEW zcl_rectangle( iv_width = 1 iv_height = 2 ). lo_container->add( lo_rectangle ). DATA(lo_triangle) = NEW zcl_triangle( iv_height = 2 iv_side = 3 ). lo_container->add( lo_triangle ). DATA(lo_iterator) = lo_container->get_iterator( )."获取了一个迭代器 WHILE lo_iterator->has_next( )."CL_OBJECT_COLLECTION_ITERATOR DATA(lo_shape) = CAST zif_shape( lo_iterator->get_next( ) )."根据不同的类，返回值 lv_result = lv_result + lo_shape->get_area( ). ENDWHILE. WRITE:/ lv_result."圆，三角形，长方形的合计值 "这里可以实现将不同的实例加入到LT_SHAPE内表中，

DATA(entry) = VALUE ty_shape( shape = lo_circle ). APPEND entry TO lt_shape. entry = VALUE ty_shape( shape = lo_rectangle ). APPEND entry TO lt_shape. entry = VALUE ty_shape( shape = lo_iterator ). APPEND entry TO lt_shape. CLEAR lv_result.

LOOP AT lt_shape REFERENCE INTO DATA(lr_shape). lo_shape = CAST zif_shape( lr_shape->shape ). lv_result = lv_result + lo_shape->get_area( ). ENDLOOP. WRITE:/ lv_result."圆，三角形，长方形的合计值