Automated Refactoring of Legacy Java Software to Enumerated Types

Modern Java languages introduce several new features that offer significant improvements over older Java technology. In this article we consider the new enum construct, which provides language support for enumerated types. Prior to recent Java languages, programmers needed to employ various patterns (e.g., the weak enum pattern) to compensate for the absence of enumerated types in Java. Unfortunately, these compensation patterns lack several highly-desirable properties of the enum construct, most notably, type safety. We present a novel fully-automated approach for transforming legacy Java code to use the new enumeration construct. This semantics-preserving approach increases type safety, produces code that is easier to comprehend, removes unnecessary complexity, and eliminates brittleness problems due to separate compilation. At the core of the proposed approach is an interprocedural type inferencing algorithm which tracks the flow of enumerated values. The algorithm was implemented as an open source, publicly available Eclipse plug-in and evaluated experimentally on 17 large Java benchmarks. Our results indicate that analysis cost is practical and the algorithm can successfully refactor a substantial number of fields to enumerated types. This work is a significant step towards providing automated tool support for migrating legacy Java software to modern Java technologies

Automated Refactoring of Legacy Java Software to Default Methods

Java 8 default methods, which allow interfaces to contain (instance) method implementations, are useful for the skeletal implementation software design pattern. However, it is not easy to transform existing software to exploit default methods as it requires analyzing complex type hierarchies, resolving multiple implementation inheritance issues, reconciling differences between class and interface methods, and analyzing tie-breakers (dispatch precedence) with overriding class methods to preserve type-correctness and confirm semantics preservation. In this paper, we present an efficient, fully-automated, type constraint-based refactoring approach that assists developers in taking advantage of enhanced interfaces for their legacy Java software. The approach features an extensive rule set that covers various corner-cases where default methods cannot be used. To demonstrate applicability, we implemented our approach as an Eclipse plug-in and applied it to 19 real-world Java projects, as well as submitted pull requests to popular GitHub repositories. The indication is that it is useful in migrating skeletal implementation methods to interfaces as default methods, sheds light onto the pattern’s usage, and provides insight to language designers on how this new construct applies to existing software

Towards Improving Interface Modularity in Legacy Java Software through Automated Refactoring

The skeletal implementation pattern is a software design pattern consisting of defining an abstract class that provides a partial interface implementation. However, since Java allows only single class inheritance, if implementers decide to extend a skeletal implementation, they will not be allowed to extend any other class. Also, discovering the skeletal implementation may require a global analysis. Java 8 enhanced interfaces alleviate these problems by allowing interfaces to contain (default) method implementations, which implementers inherit. Java classes are then free to extend a different class, and a separate abstract class is no longer needed; developers considering implementing an interface need only examine the interface itself. We argue that both these benefits improve software modularity, and discuss our ongoing work in developing an automated refactoring tool that would assist developers in taking advantage of the enhanced interface feature for their legacy Java software

Enumeration Refactoring: A Tool for Automatically Converting Java Constants to Enumerated Types

Java 5 introduces several new features that significantly improve older Java technology. We consider the new enum construct, which provides language support for enumerated types. Before Java 5, programmers needed to employ various patterns to compensate for the absence of enumerated types in Java. Unfortunately, these compensation patterns lack several highly desirable properties of the enum construct, notably type-safety. We demonstrate an automated refactoring tool called Convert Constants to Enum for transforming legacy Java code to use the new enumeration construct. An interprocedural type inferencing algorithm that tracks the flow of enumerated values drives the approach, and the tool is implemented as a seamless extension to existing refactoring support in Eclipse. The resulting code is semantically equivalent to the original, increasingly type-safe, easier to comprehend, less complex, and supports separate compilation

A case study of refactoring large-scale industrial systems to efficiently improve source code quality

Refactoring source code has many benefits (e.g. improving maintainability, robustness and source code quality), but it takes time away from other implementation tasks, resulting in developers neglecting refactoring steps during the development process. But what happens when they know that the quality of their source code needs to be improved and they can get the extra time and money to refactor the code? What will they do? What will they consider the most important for improving source code quality? What sort of issues will they address first or last and how will they solve them? In our paper, we look for answers to these questions in a case study of refactoring large-scale industrial systems where developers participated in a project to improve the quality of their software systems. We collected empirical data of over a thousand refactoring patches for 5 systems with over 5 million lines of code in total, and we found that developers really optimized the refactoring process to significantly improve the quality of these systems. © 2014 Springer International Publishing

30 Years of Software Refactoring Research:A Systematic Literature Review

Due to the growing complexity of software systems, there has been a dramatic increase and industry demand for tools and techniques on software refactoring in the last ten years, defined traditionally as a set of program transformations intended to improve the system design while preserving the behavior. Refactoring studies are expanded beyond code-level restructuring to be applied at different levels (architecture, model, requirements, etc.), adopted in many domains beyond the object-oriented paradigm (cloud computing, mobile, web, etc.), used in industrial settings and considered objectives beyond improving the design to include other non-functional requirements (e.g., improve performance, security, etc.). Thus, challenges to be addressed by refactoring work are, nowadays, beyond code transformation to include, but not limited to, scheduling the opportune time to carry refactoring, recommendations of specific refactoring activities, detection of refactoring opportunities, and testing the correctness of applied refactorings. Therefore, the refactoring research efforts are fragmented over several research communities, various domains, and objectives. To structure the field and existing research results, this paper provides a systematic literature review and analyzes the results of 3183 research papers on refactoring covering the last three decades to offer the most scalable and comprehensive literature review of existing refactoring research studies. Based on this survey, we created a taxonomy to classify the existing research, identified research trends, and highlighted gaps in the literature and avenues for further research.Comment: 23 page

30 Years of Software Refactoring Research: A Systematic Literature Review

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155872/4/30YRefactoring.pd

Test Naming Failures. An Exploratory Study of Bad Naming Practices in Test Code

Unit tests are a key component during the software development process, helping ensure that a developer\u27s code is functioning as expected. Developers interact with unit tests when trying to understand, maintain, and when updating code. Good test names are essential for making these various processes easier, which is important considering the substantial costs and effort of software maintenance. Despite this, it has been found that the quality of test code is often lacking, specifically when it comes to test names. When a test fails, its name is often the first thing developers will see when trying to fix the failure, therefore it is important that names are of high quality in order to help with the debugging process. The objective of this work was to find anti-patterns having to do with test method names that may have a negative impact on developer comprehension. In order to do this, a grounded theory study was conducted on 12 open-source Java and C# GitHub projects. From this dataset, many patterns were discovered to be common throughout the test code. Some of these patterns fit the necessary criteria of anti-patterns that would probably hinder developer comprehension. With the avoidance of these anti-patterns it is believed that developers will be able to write better test names that can help speed the time to debug errors as test names will be more comprehensive

Defaultification Refactoring: A Tool for Automatically Converting Java Methods to Default

Enabling interfaces to declare (instance) method implementations, Java 8 default methods can be used as a substitute for the ubiquitous skeletal implementation software design pattern. Performing this transformation on legacy software manually, though, may be non-trivial. The refactoring requires analyzing complex type hierarchies, resolving multiple implementation inheritance issues, reconciling differences between class and interface methods, and analyzing tie-breakers (dispatch precedence) with overriding class methods. All of this is necessary to preserve type-correctness and confirm semantics preservation. We demonstrate an automated refactoring tool called Migrate Skeletal Implementation to Interface for transforming legacy Java code to use the new default construct. The tool, implemented as an Eclipse plug-in, is driven by an efficient, fully-automated, type constraint-based refactoring approach. It features an extensive rule set covering various corner-cases where default methods cannot be used. The resulting code is semantically equivalent to the original, more succinct, easier to comprehend, less complex, and exhibits increased modularity. A demonstration can be found at http://youtu.be/YZHIy0yePh8