Exploiting bad-smells and object-oriented characteristics to prioritize classes for refactoring

Bad-smell indicates code-design flaws and poor software-quality that weaken software design and inversely affects software development. It also works as a catalyst for bugs and failures in the software system. Refactoring methods are used by software practitioners as corrective actions for bad-smells. The problem relies in the fact that there are over seventy refactoring methods available in literature and multiple refactoring methods can be used to nullify the effect of a particular bad-smell. So, it becomes very difficult to apply refactoring on complete source-code and almost impossible if software size is dramatically large. Thus, there arises a need for prioritizing classes in some way. This study aims at applying refactoring solution to only severely affected classes to improve the overall software quality. We proposed a framework that detects a small subset of classes from the entire source-code instantly require refactoring. This prioritization of classes is based on two factors-severity of the presence of bad-smells and object-oriented characteristics. The approach is evaluated on eight open-source Java software systems using ten most common bad-smells and six widely known C&K metrics. Both these factors help in calculating a new metric Quality Depreciation Index Rule (QDIR) that exposes those classes that are highly affected by bad-smells and demand an immediate refactoring solution. Results of the empirical study indicate that QDIR is an effective metric to remove bad-smells in an environment of stringent time constraints and limited cost making the maintenance of software system easier and effective with enhanced software quality.