Dutchyn, Christopher2013-01-032013-01-032012-052012-06-14May 2012http://hdl.handle.net/10388/ETD-2012-05-457Current integrated development environments such as Eclipse provide strong support for object- oriented automatic refactorings; however, the same cannot be said about aspect-oriented refactor- ings. Refactoring of design patterns is one area where aspect refactoring automation remains to be explored in depth and few current tools are available to support it. To support aspect refactoring tools we present the AJRefactor plug-in, a semi-automatic refactoring tool for the observer pattern, a widely-used solution in the design of object-oriented programs. Aspect refactoring of the observer pattern allows aspects to capture pattern-specific code into a more modularized unit, and local- izes the code of participating classes. After applying AJRefactor on two Java projects JHotDraw and Prevayler, the results showed that AJRefactor was able to refactor 75% of the total observer instances found in both projects. Also, the refactoring enhanced the modularity and loosens the coupling of the pattern classes. Finally, the results showed a significant time savings and a small reduction in code size when refactoring with AJRefactor.engrefactoring, AspectJ, Eclipse, plug-intext