Refactoring is the process of changing the structure of code without changing its behavior. Refactoring can be semi-automated with tools, which should make it easier for programmers to refactor quickly and correctly. However, we have observed that many tools do a poor job of communicating errors triggered by the refactoring process and that programmers using them sometimes refactor slowly, conservatively, and incorrectly. In this paper we characterize problems with current refactoring tools, demonstrate three new tools to assist in refactoring, and report on a user study that compares these new tools against existing tools. The results of the study show that speed, accuracy, and user satisfaction can be significantly increased. From the new tools we induce a set of usability recommendations that we hope will help inspire a new generation of programmer-friendly refactoring tools.

Abstract. Refactoring is the process of changing the structure of code without changing its behavior. Refactoring can be semi-automated with the help of tools, but many existing tools do a poor job of communicating errors triggered by the programmer. This poor communication causes programmers to refactor slowly, conservatively, and incorrectly. In this paper, I demonstrate the problems with current refactoring tools, characterize three new alternative program views to assist in refactoring, and describe a user study that compares these new views against existing tools. The results of the study show that both the speed and accuracy of refactoring can be increased using these new views. The new views exhibit several desirable properties for future refactoring tools. 1

Refactoring, the process of changing the structure of code without changing its behavior, can be semi-automated with the help of tools. However, many tools do a poor job of communicating errors triggered by the refactoring process. This poor communication causes programmers to refactor slowly, conservatively, and incorrectly. In this paper we demonstrate problems with current refactoring tools, characterize three new tools to assist in refactoring, and describe a user study that compares these new tools against existing tools. The results of the study show that the speed, accuracy, and user satisfaction can be significantly increased The new tools have inspired a set of usability recommendations that we hope will help build a new generation of programmer-friendly refactoring tools.

Tools that perform semi-automated refactoring are currently under-utilized by programmers. If more programmers adopted refactoring tools, software projects could make enormous productivity gains. However, as more advanced refactoring tools are designed, a great chasm widens between how the tools must be used and how programmers want to use them. The proposed research will bridge this chasm by exposing usability guidelines that will direct the design of the next generation of programmer-friendly refactoring tools, so that refactoring tools fit the way programmers behave, not vice-versa. int newBalance = balance- payment; System.out.println ( newBalance); Moderately complex refactorings include Extract Method, where part of the body of a long method is replaced with a call to a new method containing the same code, and Push Up Method, where a method is moved from its subclass to a superclass. For example, these classes 1.

Tools that perform semi-automated refactoring are currently under-utilized by programmers. If more programmers adopted refactoring tools, software projects could make enormous productivity gains. However, as more advanced refactoring tools are designed, a great chasm widens between how the tools must be used and how programmers want to use them. This dissertation begins to bridge this chasm by exposing usability guidelines to direct the design of the next generation of programmer-friendly refactoring tools, so that refactoring tools fit the way programmers behave, not vice-versa.