An Empirical Study of the Impact of Code Smell on File Changes

Code smells are considered to have negative impacts on software evolution and maintenance. Many researchers have conducted studies to investigate these effects and correlations. However, because code smells constantly change in the evolution, understanding these changes and the correlation between them and the operations of source code files is helpful for developers in maintenance. In this paper, on four popular Java projects with 58 release versions, we conduct an extensive empirical study to investigate the correlation between code smells and basic operations of source code files. We find that, the density of code smells decreases with the software evolution. The files containing smells have a higher likelihood to be modified while smells are not strongly correlated with adding or removing files. Furthermore, some certain smells have significant impact on file changes. These findings are helpful for developers to understand the evolution of code smells and better focus on quality assurance.