Chris Parnin
Christian Bird
ABSTRACT
Support for generic programming was added to the Java language in 2004, representing perhaps the most significant change to one of the most widely used programming languages today. Researchers and language designers anticipated this addition would relieve many long-standing problems plaguing developers, but surprisingly, no one has yet measured whether generics actually provide such relief. In this paper, we report on the first empirical investigation into how Java generics have been integrated into open source software by automatically mining the history of 20 popular open source Java programs, traversing more than 500 million lines of code in the process. We evaluate five hypotheses, each based on assertions made by prior researchers, about how Java developers use generics. For example, our results suggest that generics do not significantly reduce the number of type casts and that generics are usually adopted by a single champion in a project, rather than all committers.
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Index Terms
- Java generics adoption: how new features are introduced, championed, or ignored
Recommendations
Converting Java classes to use generics
OOPSLA '04: Proceedings of the 19th annual ACM SIGPLAN conference on Object-oriented programming, systems, languages, and applicationsGenerics offer significant software engineering benefits since they provide code reuse without compromising type safety. Thus generics will be added to the Java language in the next release. While this extension to Java will help programmers when they ...
Adoption and use of Java generics
Support for generic programming was added to the Java language in 2004, representing perhaps the most significant change to one of the most widely used programming languages today. Researchers and language designers anticipated this addition would ...
Object and reference immutability using Java generics
ESEC-FSE '07: Proceedings of the the 6th joint meeting of the European software engineering conference and the ACM SIGSOFT symposium on The foundations of software engineeringA compiler-checked immutability guarantee provides useful documentation, facilitates reasoning, and enables optimizations. This paper presents Immutability Generic Java (IGJ), a novel language extension that expresses immutability without changing Java'...
Reviews
Andrew Brooks
Support for generics in Java was introduced in 2004. Until now, the impact of this introduction has been little studied. This paper presents results from an automatic analysis of the use of generics in the full version histories of the top 20 open-source projects at ohloh.net. Figure 1 reveals considerable variation in the proportions of raw and parameterized types. Five projects made no use of generics. One project, FindBugs, made almost no use of raw types. Do generics reduce casts__?__ Figure 2 reveals small dips in the number of casts when the number of parameterized types increases, but only six projects exhibited such dips. Other software development practices must be responsible for the general decline in the number of casts shown in figure 2. The authors describe as dubious the argument that generics reduce casts. Is old code converted to use generics__?__ Figure 3(a) shows a strong pattern of conversion for SQuirrel SQL. Over 40 percent of raw types were converted over a five-month period. Only three projects, however, had a conversion rate over 12 percent. The authors conclude that most projects do not show large-scale conversions and that introducing new language features does not by itself guarantee their adoption. Though this study did not use questionnaires and interviews to determine reasons for the trends found, it nevertheless provides remarkable insights. As such, I strongly recommended it to Java developers and instructors, and those engaged in language design. Online Computing Reviews Service
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