Dissertation Submitted to the Graduate Faculty of Auburn University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy
Repatterning: Improving the Reliability of Android Applications with an Adaptation of Refactoring by Bradley Christian Dennis A dissertation submitted to the Graduate Faculty of Auburn University in partial fulfillment of the requirements for the Degree of Doctor of Philosophy Auburn, Alabama August 2, 2014 Keywords:Refactoring, Code Smells, Patterns, Non-functional Requirements, Verification Copyright 2014 by Bradley Christian Dennis Committee: David Umphress, Chair, Associate Professor of Computer Science and Software Engineering James Cross, Professor of Computer Science and Software Engineering Dean Hendrix, Associate Professor of Computer Science and Software Engineering Jeffrey Overbey, Assistant Research Professor of Computer Science and Software Engineering Abstract Studies of Android applications show that NullPointerException, OutofMemoryError, and BadTokenException account for a majority of errors observed in the real world. The technical debt being born by Android developers from these systemic errors appears to be due to insufficient, or erroneous, guidance, practices, or tools. This dissertation proposes a re- engineering adaptation of refactoring, called repatterning, and pays down some of this debt. We investigated 323 Android applications for code smells, corrective patterns, or enhancement patterns related to the three exceptions. I then applied the discovered patterns to the locations suggested by the code smells in fifteen randomly selected applications. I measured the before and after reliability of the applications and observed a statistically significant improvement in reliability for two of the three exceptions. I found repatterning had a positive effect on the reliability of Android applications. This research demonstrates how refactoring can be generalized and used as a model to affect non-functional qualities other than the restructuring related attributes of maintainability and adaptability.
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