Constructor OOABAP

8/12/2019 Constructor OOABAP

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What is Constructor

Definition:

Constructor is a one special method which is automatically /

Implicitly called when an object is created.

Purpose/Use:

Constructor are used to initialize current class object.


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Rules / Characteristic

Constructor name must be CONSTRUCTOR, or

CLASS_CONSTRUCTOR.

Constructor can be inherited into derived class.

Class Constructor can not be inherited into derived class.

Because every class constructor is made for initialize the its

own attribute of the class but not for initialize another class

attribute.


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Types of Constructor

Constructor (Instance Constructor)

Class Constructor ( Static Constructor)


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Instance Constructor

To create a Instance Constructor use Constructor keyword.

Instance constructor is executed automatically for every object

creation.

Instance constructor is by default is private.

We will not provide Explicit any return type to constructor.


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Static Constructor

To design static Constructor use CLASS_CONSTRUCTOR.

Static constructor is executed automatically for either

i. When class name is used. (Only Once)

ii. When first object is created. (Only Once)

Note:

Static Constructor is triggered in the above 2 scenario but which one scenariocomes first.

Class Constructor is by default is public.

We will not provide any parameter to Class-Constructor.

We can not inherit Class Constructor.


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Constructor

Method

Methods are executedexplicitly by developer.

Methods can haveimporting, exporting,changing, returningparameters.

Constructor

Constructors are executedimplicitly.

We can not provide explicitlyreturning parameters toinstance constructor butStatic constructor cant haveany parameters.


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Advantage

I) Constructor eliminate in a placing value.

0

0

X X X

10

20

X X X

Object Object

ConstructorMethod

Class Class


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II) Constructor eliminate calling of Ordinary Method.

Ordinary Method:

All Method which are not similar to CONSTRUCTOR

name is know as Ordinary Method.

Special Method:

All Method which are similar to CONSTRUCTOR name is

known as Special Method.


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Overloaded Constructor

*** ABAP Does not support Overloaded Constructor

Over Load= Class name is Same + Signature is Different

Signature:

No of Parameter

Type of Parameter

Order of Parameter

At Least one will be

Different


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Visibility Chart

Private Protected Public

Private Y Y Y

Protected N Y Y

Public N N Y


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Method Parameters

Importing

Provide the input value in report program.

We can use more then importing parameters.

Exporting

Provide the output value in report program.

It will return value when program is executed completely.We can pass table throw exporting parameters.

We can use more then exporting parameters.


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Method Parameters

Changing

It treated as a importing as well as exporting parameters.

We can use more then changing parameters.

Returning

It will return the value in the mid of program execution.

We can not pass table throw returning parameters. If we are using returning parameters we cant use exporting

and changing parameters.

We cant use more then one returning parameters.


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Function Module versus Method

Function Module

Returning parameter is notthere.

Method

Returning parameters isthere.


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Constructor OOABAP

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