Defining Relationships Between Object Types (SAP Library

Defining Relationships Between Object Types

You can define the following relationships between two object classes:

Inheritance between two classes
Extending the functions of a class by implementing interfaces. This is a relationship between classes and interfaces

Compound interfaces. This is a relationship between interfaces.

Characterization

Inheritance is a relationship between classes. It allows you to derive a new class from the definition of an existing class. The new class is called a subclass, the existing class is its superclass. Inheritance is used to create a subclass that is more specialized than its superclass. You can add new components to a subclass, and also redefine the methods that it inherits. The result of inheritance is a class hierarchy. The Class Builder allows you to create a class hierarchy very simply. You can create a subclass for any class that is not defined as final, and can also define a direct superclass for a class that was itself not derived.

Interfaces allow you to extend a class definition. When a class implements an interface, all of the interface components appear as components of the class. You can access these components either using a class reference or an interface reference.
Interfaces allow you to work with several different classes in a uniform way. The actual implementation of the interface components takes place in the classes. Consequently, interfaces provide a way of separating the definition and implementation of components.
Interfaces can contain attributes, methods, and events, but also other interfaces. Classes that implement a compound interface must also implement all of its components. Compound interfaces are a specialization of their component interfaces.

Features

Creating subclasses

Redefining inherited methods

Creating superclasses

Assigning interfaces to classes

Defining and implementing interface methods within a class definition

Creating compound interfaces

Activities

Implementing Interfaces in Classes

Creating Subclasses

Nesting Interfaces