Introduction

A Java Interface, as defined in the Java language syntax, is not limited to having operations - it can have Java Field, Class, or Interface members. For this reason, Java Interfaces are modeled as classes stereotyped <<JavaInterface>>.

The UML interface has no direct mapping to a language construct in Java or J2EE development.

Interfaces in Java Design

Even though UML interfaces do not map to a language construct in Java or J2EE, there are situations where the designer might want to use them. Some possible reasons are:

• potentially target other languages and technologies
• express the idea of an interface without initially deciding if a Java Interface, or some kind of delegate or access class, will be used

If the implementation language is Java, you might decide to use <<JavaInterface>> stereotyped classes in the Design Model in place of UML interfaces. This allows the Design Model to evolve more easily and remain consistent with the Implementation Model (see Concept: Mapping from Design to Code).

Note that <<JavaInterface>> stereotyped classes cannot be represented as lollipops on the outside of UML subsystems or components. Instead, the exposed interfaces are shown as publicly visible elements owned by a subsystem or as publicly visible elements residing on a UML component.

Interfaces in EJB Design

EJB interfaces are specializations of Java interfaces. Their stereotypes are described in Guideline: Identifying Enterprise JavaBeans (EJBs).

The designer might use UML interfaces, <<JavaInterface>> stereotyped classes, or EJB-specific stereotyped classes to model interfaces depending on how closely the designer wants to map to a particular implementation.