Efficiently refactoring java applications to use generic libraries

TL;DR: In this paper, the authors present a refactoring that replaces raw references to generic library classes with parameterized references, which eliminates the need for potentially unsafe downcast when retrieving elements from containers.

Abstract: Java 1.5 generics enable the creation of reusable container classes with compiler-enforced type-safe usage. This eliminates the need for potentially unsafe down-casts when retrieving elements from containers. We present a refactoring that replaces raw references to generic library classes with parameterized references. The refactoring infers actual type parameters for allocation sites and declarations using an existing framework of type constraints, and removes casts that have been rendered redundant. The refactoring was implemented in Eclipse, a popular open-source development environment for Java, and laid the grounds for a similar refactoring in the forthcoming Eclipse 3.1 release. We evaluated our work by refactoring several Java programs that use the standard collections framework to use Java 1.5's generic version instead. In these benchmarks, on average, 48.6% of the casts are removed, and 91.2% of the compiler warnings related to the use of raw types are eliminated. Our approach distinguishes itself from the state-of-the-art [8] by being more scalable, by its ability to accommodate user-defined subtypes of generic library classes, and by being incorporated in a popular integrated development environment.