Using structural and semantic metrics to improve class cohesion

Several refactoring methods have been proposed in the literature to improve the cohesion of classes. Very often, refactoring operations are guided by cohesion metrics based on the structural information of the source code, such as attribute references in methods. In this paper we present a novel approach to guide the extract class refactoring (M. Fowler, 1999), taking into account structural and semantic cohesion metrics. The proposed approach has been evaluated in a case study conducted on JHotDraw, an open source software system. The achieved results revealed that the performance achieved with the proposed approach significantly outperforms the results achieved with methods considering only structural or semantic information. The proposed approach has also been integrated in the Eclipse platform.