  Nowadays, modern applications are developed using components written in
different programming languages. These systems introduce several advantages.
However, as the number of languages increases, so does the challenges related
to the development and maintenance of these systems. In such situations,
developers may introduce design smells (i.e., anti-patterns and code smells)
which are symptoms of poor design and implementation choices. Design smells are
defined as poor design and coding choices that can negatively impact the
quality of a software program despite satisfying functional requirements.
Studies on mono-language systems suggest that the presence of design smells
affects code comprehension, thus making systems harder to maintain. However,
these studies target only mono-language systems and do not consider the
interaction between different programming languages. In this paper, we present
an approach to detect multi-language design smells in the context of JNI
systems. We then investigate the prevalence of those design smells.
Specifically, we detect 15 design smells in 98 releases of nine open-source JNI
projects. Our results show that the design smells are prevalent in the selected
projects and persist throughout the releases of the systems. We observe that in
the analyzed systems, 33.95% of the files involving communications between Java
and C/C++ contains occurrences of multi-language design smells. Some kinds of
smells are more prevalent than others, e.g., Unused Parameters, Too Much
Scattering, Unused Method Declaration. Our results suggest that files with
multi-language design smells can often be more associated with bugs than files
without these smells, and that specific smells are more correlated to
fault-proneness than others.

Software Engineering