Mapping UML Associations into Java Code

Object-oriented programming languages do not contain syntax or semantics to express associations directly. Therefore, UML associations have to be implemented by an adequate combination of classes, attributes and methods. This paper presents some principles for the implementation of UML binary associations in Java, paying special attention to multiplicity, navigability and visibility. Our analysis has encountered some paradoxes in the specification of visibility for bidirectional associations. These principles have been used to write a series of code patterns that we use in combination with a tool that generates code for associations, which are read from a model stored in XMI format.