Creating extends relationships between Java classes in domain modeling class diagrams

You can use domain modeling class diagrams to create extends relationships between Java™ classes.

Before you begin

You cannot create extends relationships between Java classes in the following situations:

Between two Java classes where the sub Java class already extends another class (multiple extends or inheritance relationships are not supported in Java)
Between two Java classes where the super class is a final class
When the source type is in a named project and the target type is in a default package.

You must have a domain modeling class diagram open.

You can also use the modeling assistant to create extends relationships.

In the Palette, click Extends.
In the diagram editor, click the sub (client) Java class, drag it to the super (supplier) Java class, and release the mouse button.