这一节通过一个最简单的例子来介绍如何使用类，以及类的属性和方法。
先把背景介绍一下：
创建一个lcl_airplane类，通过方法set_attributes设置它的属性，通过display_attributes显示实例的属性，通过display_n_o_airplanes显示已经创建的实例的个数。
*———————————————————————-*
* INCLUDE Z_SAMPLE_LCL_AIRPLANE *
*———————————————————————-*
******************************************
* Definition part
******************************************
CLASS lcl_airplane DEFINITION.
*——————————
* Public section
*——————————
PUBLIC SECTION.
TYPES: t_name(25) TYPE c.
METHODS:
constructor, “初始化类
set_attributes IMPORTING p_name TYPE t_name
p_planetype TYPE saplane-planetype,
display_attributes,
display_n_o_airplanes.
*——————————
* Private section
*——————————
PRIVATE SECTION.
* Private attributes
DATA: name(25) TYPE c,
planetype TYPE saplane-planetype.
* Private static attribute
CLASS-DATA n_o_airplanes TYPE i.
ENDCLASS.
******************************************
* Implementation part
******************************************
CLASS lcl_airplane IMPLEMENTATION.
METHOD constructor.
* Counts number of instances
n_o_airplanes = n_o_airplanes + 1.
ENDMETHOD.
METHOD set_attributes.
name = p_name.
planetype = p_planetype.
ENDMETHOD.
METHOD display_attributes.
WRITE:/ ‘Name:’, name, ‘Planetype:’, planetype.
ENDMETHOD.
METHOD display_n_o_airplanes.
WRITE: / ‘No. planes:’, n_o_airplanes.
ENDMETHOD.
ENDCLASS.
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REPORT ZBOBO_OO_011 .
Include z_sample_lcl_airplane.
* Create reference to class lcl_airplane
DATA: airplane1 TYPE REF TO lcl_airplane,
airplane2 TYPE REF TO lcl_airplane.
START-OF-SELECTION.
* Create instance
CREATE OBJECT airplane1.
CALL METHOD: airplane1->display_n_o_airplanes.
CREATE OBJECT airplane2.
* Setting attributes using a method with parameters
CALL METHOD airplane1->set_attributes EXPORTING p_name = ‘Kurt’
p_planetype = ‘MD80′.
END-OF-SELECTION.
* Using methods
CALL METHOD: airplane1->display_n_o_airplanes,
airplane1->display_attributes.
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