Static Method VS Instance Method

-

 Introduction:

  • We will cover the following basic concepts: 
  1. Creating a Global Class in SE24.
  2. Understand the basics of Methods.
  3. Understand the basics of 'Types of Methods'.
  4. Define and Implement a Static Method & an Instance Method.
  5. Call a Static and an Instance Method in the SE38 program.
  6. Bonus Point.

Lets Start:
  1. Create a Global Class: ZGLOBAL_CLASS in Se24.


  • Choose the following options to create a Class.
    • Choose 'Class' Radio Button.

 
  •  Choose 'Usual ABAP Class' and 'Final' Check Box.


      2. Now let us understand the basics of Methods.
  • Methods are just like Function Modules. 
  • Check out the below comparison that will help you to get a basic understanding of Methods.



        3. Now let us understand the basics of  'Types of Methods' with a below simple comparison.




    
       4. Now let us define and implement a Static Method & an Instance Method.
  • Create METHOD_INSTANCE & METHOD_STATIC in Methods Tab.
  • And set the level of Methods as Instance & Static respectively as shown below.


 
  • To see how the generated code looks in the Public Section follow the below steps.
    • Goto->Sections->Public section.


    • We can see generated code as below.


  • Create an implementation of the METHOD_INSTANCE as shown below.


  • Similarly create an implementation for METHOD_STATIC as shown below.



     
      5. Now let us call these Static and the Instance Methods in the SE38 program.

  • First let us call the Static Method METHOD_STATIC.
    • We call METHOD_STATIC directly using the Class Component selector ( => ) symbol.
    • There is no need to create an Object for the Static Method.


    • Now Save, Check & Activate the Program. the program activates without any error.
    • Execute the program, The method METHOD_STATIC gets called successfully and the WRITE statement inside the implementation of the method gets executed.


  • Now let us code for the call of Instance Method METHOD_INSTANCE.
    • Here we call the Instance Method just like we called our Static Method using Class Component Selector ( => ) symbol.


    • Now Save, Check &  try to Activate the Program, we will an ERROR as shown below.


    • As the error suggests we cannot call an Instance Method using Class=>Method.
    • So we will create an Object with the class reference parameter LR_CLASS.
    • Call the METHOD_INSTANCE using the Created Object as shown below.


    • Now Save, Check & Activate the Program. the program activates without any error.
    • Execute the program, The methods METHOD_STATIC & METHOD_INSTANCE get called successfully and the WRITE statement inside the implementation of the methods get executed.


    • Now, we know the basics of Theoretical and Practical implementation of  STATIC and INSTANCE Methods.

     6. Now for the BONUS POINT.
  • Let us Try to Call the Static Method METHOD_STATIC using our created Object LR_CLASS. That is, call the Static Method using 'Object Component Selector' just like the Instance Method.

  • Guess what? Surprisingly it works.


  • Find the complete sample code below.
REPORT zglobal_class_methods1.
*Consume the methods of Class ZGLOBAL_CLASS

*Call the Static Method of the Class
zglobal_class=>method_static( ).

*Call the Instance Method of the Class
*Declare local variable concerning the class
DATA:lr_class TYPE REF TO zglobal_class.

*Create an object for the class
CREATE OBJECT lr_class.
*Cursor to Next Line
WRITE /.
*Call Method
CALL METHOD lr_class->method_instance.

*Call the Static Method of the Class using Created Object
*Cursor to Next Line
WRITE /.
*Cursor to Next Line
WRITE / 'Using Class OBJECT:'.
*Call Method
CALL METHOD lr_class->method_static.

Comments

Post a Comment

Popular posts from this blog

Class Visibility

-
Image
  Introduction:    We will cover the following basic concepts: Simple example class, specially designed to understand the basics of Class Visibility. How visibility of the class components like attributes and methods work. How can a developer utilize the visibility property to his advantage ?.   Use of 'Me' variable Demonstration of visibility in an executable eclipse program. Why use Visibility?   Lets Start : 1. Let us create a class in HANA Eclipse with the following structure. We will define the below components in the class definition. PUBLIC SECTION : This means the class components like Attributes and Methods defined in this section are visible outside the  Class, in Sub-Classes, in an Executable Program. We will create Attribute:  CV_PUBLIC_ATTR with default value 'PUBLIC SECTION'. We will create Method: CM_PUBLIC_METHOD,CM_PUBLIC_MAIN_METHOD. PROTECTED SECTION : This ...
Read more

Special Method: Constructor

-
Image
  Introduction:    We will cover the following basic concepts: Understand, what are constructors. Simple example class, specially designed to understand the basics of Constructors. Create a program to demonstrate different ways constructors behave. Why Constructors? 1. So, what are constructors? Let us understand the basics of the constructors by studying simple differences between normal methods and constructors. 2. Let us start our example by creating a HANA Eclipse class with the below structure. We will create the below 4 methods in the visibility  PUBLIC SECTION of the CLASS DEFINITION . Create a Special Instance Method Constructor with the name CONSTRUCTOR, this is the default name we use to create an instance constructor. We will also create a Normal Instance Method with the name INSTANCE_METHOD. Create a Special Static Method Constructor with the name CLASS_CONSTRUCTOR, this is the default name we use to create a static constructor. And similarly we will ...
Read more

Class Inheritance

-
Image
    Introduction:    We will cover the following basic concepts: Understand the basics of Class Inheritance. Simple example class to understand how we can work with Class Inheritance in different scenarios. We will see the use of SUPER and ME keywords in the context of Inheritance. Create a program to demonstrate the different ways to call methods using Inheritance. Why Class Inheritance? Lets Start 1. Let us create the below comparison chart to understand the basics of  CLASS INHERITANCE. Basic Inheritance Tree Inheritance Basic Comparison Table 2. Lets us create a simple eclipse class and make it work for different scenarios. We will add one method in each visibility section of the Eclipse Class as shown below. PUBLIC_METHOD, PROTECTED_METHOD, and PRIVATE METHOD. Now let us create the implementations for the created methods. Here we have created a FINAL CLASS ( i.e. add the FINAL keyword in the definition section of the class) just to see what happens if we ...
Read more