ABAP Keyword Documentation → ABAP − Reference → Declarations → Declaration Statements → Classes and Interfaces → ABAP Objects - Overview
Objects
Objects are instances of classes. There can be any number of objects or instances in a class. Each object has a unique identity and its own attributes.
By default, all objects have the same priority in the data area of an internal session. This means that objects can only be accessed from within an internal session.
For cross-transaction objects, shared objects exist that can be accessed by all programs of an AS Instance at the same time.
Object Services are available for handling persistent objects in the database. These associate the attributes of objects with the content of database tables and can execute object-oriented transactions.
Other versions: 7.31 | 7.40 | 7.54
Creating Objects
Before an object can be created, an object reference variable is required that can point to the required class:
- Once a class reference variable
objis declared for a classclass, an object of that class can be created using the statement CREATE OBJECT obj. This statement creates an instance of the classclassand the reference variableobjcontains a reference to this object.
- Once a class reference variable
objis declared for a superclass of the classclassor an interface reference variableobjfor an interface implemented by the classclass, the addition TYPE class of the statementCREATE OBJECT objcan be used to create an instance of the classclass.
The instance operator NEW enables objects to be created in
general expression positions.
Access to Instance Components
A program can access the visible instance components of an object only by using references in reference variables. For the syntax, see Accessing Components of Classes.
Lifetime of Objects
An object is kept alive for as long as it is used in the internal session (known as the heap). An object is used for as long as at least one heap reference points to the object, to an instance attribute, or to a part of the instance attribute or as long as at least one method of the object is registered as an event handler. Field symbols to which an instance attribute or part of an instance attribute is assigned still work in the same way as data references.
As soon as an object has no more references and none of its methods is registered as an event handler, it can be deleted by Garbage Collector. This releases the identity of the object to be taken by a new object.
Note
Alongside these regular references, weak references represented by objects exist that do not keep an object alive.