{"id":7228,"date":"2025-08-01T01:45:51","date_gmt":"2025-07-31T20:15:51","guid":{"rendered":"https:\/\/www.sapewmhelp.com\/?question=constructor-in-abap"},"modified":"2025-08-01T01:45:51","modified_gmt":"2025-07-31T20:15:51","slug":"constructor-in-abap","status":"publish","type":"question","link":"https:\/\/www.sapewmhelp.com\/?question=constructor-in-abap","title":{"rendered":"Constructor in ABAP"},"content":{"rendered":"

A constructor is a special method automatically called when an object is created using CREATE OBJECT or NEW.<\/p>\n

Types of Constructors in ABAP<\/p>\n\n\n\n\n\n\n
Type<\/th>\nMethod Name<\/th>\nCalled On<\/th>\nPurpose<\/th>\n<\/tr>\n<\/thead>\n
Instance Constructor<\/strong><\/td>\nCONSTRUCTOR<\/code><\/td>\nWhen an object is created (NEW<\/code> or CREATE OBJECT<\/code>)<\/td>\nTo initialize instance-specific<\/strong> data<\/td>\n<\/tr>\n
Class Constructor<\/strong><\/td>\nCLASS_CONSTRUCTOR<\/code><\/td>\nWhen the class is first used<\/strong><\/td>\nTo initialize class-level (static)<\/strong> data<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

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REPORT\u00a0<\/span>zrep_lclclass.<\/span>\r\n\r\nCLASS\u00a0<\/span>zcl_demo\u00a0DEFINITION<\/span>.<\/span>\r\n\u00a0\u00a0PUBLIC\u00a0<\/span>SECTION<\/span>.<\/span>\r\n\u00a0\u00a0\u00a0\u00a0METHODS<\/span>:\u00a0<\/span>constructor,\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span>\"\u00a0Instance\u00a0constructor<\/span>\r\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0display_instance_value.<\/span>\r\n\r\n\u00a0\u00a0\u00a0\u00a0CLASS-METHODS<\/span>:\u00a0<\/span>class_constructor,\u00a0\u00a0<\/span>\"\u00a0Class\u00a0constructor<\/span>\r\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0display_class_value.<\/span>\r\n\r\n\u00a0\u00a0PRIVATE\u00a0<\/span>SECTION<\/span>.<\/span>\r\n\u00a0\u00a0\u00a0\u00a0DATA<\/span>:\u00a0<\/span>lv_instance_val\u00a0TYPE\u00a0<\/span>string.<\/span>\r\n\u00a0\u00a0\u00a0\u00a0CLASS-DATA<\/span>:\u00a0<\/span>gv_class_val\u00a0TYPE\u00a0<\/span>string.<\/span>\r\nENDCLASS<\/span>.<\/span>\r\n\r\nCLASS\u00a0<\/span>zcl_demo\u00a0IMPLEMENTATION<\/span>.<\/span>\r\n\r\n\u00a0\u00a0\"\u00a0Instance\u00a0Constructor<\/span>\r\n\u00a0\u00a0METHOD\u00a0<\/span>constructor.<\/span>\r\n\u00a0\u00a0\u00a0\u00a0lv_instance_val\u00a0=\u00a0<\/span>'Initialized\u00a0in\u00a0<\/span>CONSTRUCTOR'.<\/span>\r\n\u00a0\u00a0\u00a0\u00a0WRITE<\/span>:\u00a0<\/span>\/\u00a0'>>\u00a0Instance\u00a0CONSTRUCTOR\u00a0called'.<\/span>\r\n\u00a0\u00a0ENDMETHOD<\/span>.<\/span>\r\n\r\n\u00a0\u00a0\"\u00a0Class\u00a0Constructor<\/span>\r\n\u00a0\u00a0METHOD\u00a0<\/span>class_constructor.<\/span>\r\n\u00a0\u00a0\u00a0\u00a0gv_class_val\u00a0=\u00a0<\/span>'Initialized\u00a0in\u00a0<\/span>CLASS_CONSTRUCTOR'.<\/span>\r\n\u00a0\u00a0\u00a0\u00a0WRITE<\/span>:\u00a0<\/span>\/\u00a0'>>\u00a0CLASS_CONSTRUCTOR\u00a0called\u00a0(<\/span>only\u00a0once)<\/span>'.<\/span>\r\n\u00a0\u00a0ENDMETHOD<\/span>.<\/span>\r\n\r\n\u00a0\u00a0METHOD\u00a0<\/span>display_instance_value.<\/span>\r\n\u00a0\u00a0\u00a0\u00a0WRITE<\/span>:\u00a0<\/span>\/\u00a0'Instance\u00a0value<\/span>:<\/span>',\u00a0<\/span>lv_instance_val.<\/span>\r\n\u00a0\u00a0ENDMETHOD<\/span>.<\/span>\r\n\r\n\u00a0\u00a0METHOD\u00a0<\/span>display_class_value.<\/span>\r\n\u00a0\u00a0\u00a0\u00a0WRITE<\/span>:\u00a0<\/span>\/\u00a0'Class\u00a0value<\/span>:<\/span>',\u00a0<\/span>gv_class_val.<\/span>\r\n\u00a0\u00a0ENDMETHOD<\/span>.<\/span>\r\n\r\nENDCLASS<\/span>.<\/span>\r\n\r\nSTART-OF-SELECTION<\/span>.<\/span>\r\n\r\n*\u00a0Access\u00a0class\u00a0method\u00a0(triggers\u00a0class\u00a0constructor\u00a0first\u00a0time)<\/span>\r\n\u00a0\u00a0zcl_demo=><\/span>display_class_value(\u00a0<\/span>)<\/span>.<\/span>\r\n\r\n\u00a0\u00a0SKIP<\/span>.<\/span>\r\n\r\n*\u00a0Create\u00a0object\u00a0(triggers\u00a0instance\u00a0constructor)<\/span>\r\n\u00a0\u00a0DATA<\/span>(<\/span>lo_obj1)\u00a0<\/span>=\u00a0<\/span>NEW\u00a0<\/span>zcl_demo(\u00a0<\/span>)<\/span>.<\/span>\r\n\u00a0\u00a0lo_obj1-><\/span>display_instance_value(\u00a0<\/span>)<\/span>.<\/span>\r\n\r\n\u00a0\u00a0SKIP<\/span>.<\/span>\r\n\r\n*\u00a0Create\u00a0another\u00a0object\u00a0(instance\u00a0constructor\u00a0runs\u00a0again,\u00a0but\u00a0not\u00a0class\u00a0constructor)<\/span>\r\n\u00a0\u00a0DATA<\/span>(<\/span>lo_obj2)\u00a0<\/span>=\u00a0<\/span>NEW\u00a0<\/span>zcl_demo(\u00a0<\/span>)<\/span>.<\/span>\r\n\u00a0\u00a0lo_obj2-><\/span>display_instance_value(\u00a0<\/span>)<\/span>.<\/span>\r\n\r\n\u00a0\u00a0SKIP<\/span>.<\/span>\r\n\r\n*\u00a0Access\u00a0class\u00a0method\u00a0again\u00a0(class\u00a0constructor\u00a0NOT\u00a0triggered\u00a0again)<\/span>\r\n\u00a0\u00a0zcl_demo=><\/span>display_class_value(\u00a0<\/span>)<\/span>.<\/span><\/span> <\/code><\/pre>\n
Output:<\/p>\n
<\/p>\n<\/div>\n
 <\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"closed","template":"","question-category":[174],"question_tags":[178,171,197,217,168,177],"class_list":["post-7228","question","type-question","status-publish","hentry","question-category-ooabap","question_tags-abap","question_tags-class","question_tags-constructor","question_tags-object-orineted-programming","question_tags-ooabap","question_tags-sap"],"_links":{"self":[{"href":"https:\/\/www.sapewmhelp.com\/index.php?rest_route=\/wp\/v2\/question\/7228","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sapewmhelp.com\/index.php?rest_route=\/wp\/v2\/question"}],"about":[{"href":"https:\/\/www.sapewmhelp.com\/index.php?rest_route=\/wp\/v2\/types\/question"}],"author":[{"embeddable":true,"href":"https:\/\/www.sapewmhelp.com\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sapewmhelp.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=7228"}],"wp:attachment":[{"href":"https:\/\/www.sapewmhelp.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=7228"}],"wp:term":[{"taxonomy":"question-category","embeddable":true,"href":"https:\/\/www.sapewmhelp.com\/index.php?rest_route=%2Fwp%2Fv2%2Fquestion-category&post=7228"},{"taxonomy":"question_tags","embeddable":true,"href":"https:\/\/www.sapewmhelp.com\/index.php?rest_route=%2Fwp%2Fv2%2Fquestion_tags&post=7228"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}