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Understanding and addressing exhibitionism in Java empirical research about method accessibility


Information hiding is a positive consequence of properly defining component interfaces. Unfortunately, determining what should constitute a public interface remains difficult. We have analyzed over 3.6 million lines of Java open-source code and found that on the average, at least 20 % of defined methods are over-exposed, thus threatening public interfaces to unnecessary exposure. Such over-exposed methods may have their accessibility reduced to exactly reflect the method usage. We have identified three patterns in the source code to identify over-exposed methods. We also propose an Eclipse plugin to guide practitioners in identifying over-exposed methods and refactoring their applications. Our plugin has been successfully used to refactor a non-trivial application.

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  9. Note that a private method cannot be overridden.

  10. These scatterplots are not reported in this paper.

  11. ArgoUML, SweetHome3D, FreeMind, Ant, Cobertura, Findbugs, Jajuk, JStock, PMD, TuxGuitar




  15. version Juno (4.2)

  16. version 9.0.4

  17. version 7.0.1

  18. This happens when you call a method that does not exist and you ask Eclipse to automatically generate the missing method.


  20. Experiments were conducted on a MacBook Air, CPU 1.8 GHz Intel Core 5. 4Gb of memory.





  25. We obtained the value 35 % by computing the average of the IGAM metric from Fig. 3 in Zoller and Schmolitzky (2012).


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We thank Emmanuel Puybaret, principal author of SweetHome3D, for his feedback on our refactoring. We gratefully thank Romain Robbes and Renato Cerro for their feedback on an earlier draft of the manuscript. We also thank Hugo Manterola and Ignacio Orlando for contributing to the development of the plugin. We thank the anonymous reviewers for their comments and suggestions to improve the quality of this work. This work was partially supported by PIP Project 112-201101-00078 (CONICET) - Argentina.

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Correspondence to Santiago A. Vidal.

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Communicated by: Arie van Deursen



Table 4 Library / Frameworks analyzed
Table 5 Library / Frameworks analyzed
Table 6 Applications analyzed
Table 7 Applications analyzed
Fig. 7
figure 7

Evolution of over-exposed methods

Fig. 8
figure 8

Evolution of over-exposed methods identified in the first version of each application

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Vidal, S.A., Bergel, A., Marcos, C. et al. Understanding and addressing exhibitionism in Java empirical research about method accessibility. Empir Software Eng 21, 483–516 (2016).

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  • Method accessibility
  • Information hiding