A trait based re-engineering technique for Java hierarchies
Lorenzo Bettini, Viviana Bono, Marco Naddeo

Abstract
Traits are pure behavior components introduced in the Smalltalk community in order to integrate the traditional class inheritance with a composition mechanism: a class is composed by traits and inherits from superclasses. This offers the advantage of promoting code reuse. In this paper, we tackle the problem of re-engineering a Java hierarchy into traits, by adapting to a Java setting a methodology developed by Lienhard, Ducasse, and Arevalo for a Smalltalk setting, based on Formal Concept Analysis. We illustrate the approach by applying it to the Java input stream library. We also obtain two by-products: (i) we identify clearly some workarounds that programmers must exploit in order to overcome some of the limitations of Java single inheritance; (ii) we single out some features a Java with traits might include, as none of the proposals in the literature in this sense has taken the lead yet.