Software migration usually deals with adapting old software systems for new technologies. However, sometimes it is not feasible to migrate an existing software system to newer technologies. Then, in order to use new technology, ways must be found to backport code written for this technology to be used with older technology. For instance, the introduction of Java 5 came long with extensions of the language syntax which ease the development, but at the same time create downward incompatibilities. For some active projects, however, it is not possible to upgrade to more recent Java versions. If one still wants to use components written for Java 5, these must be backported.

In this paper, we compare existing tools which backport code developed for Java 5. We then present our own set of source-code

based transformations that do this job, and successfully apply these to two test projects.