An Approach of Extracting God Class Exploiting Both Structural and Semantic Similarity

Code smell is a sign of design and development flaws in a software system which reduces the reusability and maintainability of the system. Refactoring is a continuous practice of eliminating code smells from the source code. A God Class is one of the most common code smells where too many responsibilities are defined in a single class. God Classes reduce the quality of a system by increasing coupling and decreasing cohesion. In this paper, we propose an approach for extracting a God Class into new classes by increasing class cohesion. For this, both structural and semantic relationship between methods in a class are analyzed, and strongly related methods are clustered and suggested to be in the same class. We assessed the proposed approach on fifteen real God Classes from two well-known open source systems and it is shown that the cohesion among the classes is increased after refactoring. A comparative result of our approach with a similar existing approach is presented and it is found that our approach provides better results for almost all the experimented God Classes.