An Empirical Study into Use of Dependency Injection in Java

Abstract

Over the years many guidelines have been offered as to how to achieve good quality designs. We would like to be able to determine to what degree these guidelines actually help. To do that, we need to be able to determine when the guidelines have been followed. This is often difficult as the guidelines are often presented as heuristics or otherwise not completely specified. Nevertheless, we believe it is important to gather quantitative data on the effectiveness of design guidelines wherever possible.In this paper, we examine the use of "Dependency Injection", which is a design principle that is claimed to increase software design quality attributes such as extensibility, modifiability, testability, and reusability. We develop operational definitions for it and analysis techniques for detecting its use. We demonstrate these techniques by applying them to 34 open source Java applications.

Detecting Modularity "Smells" in Dependencies Injected with Java Annotations

“…To our best knowledge, there is no commonly accepted definition of dependency injection in literature. Although all the authors [8], [23], [14] agree that its underlying idea is simple, the definitions they give are explanatory, and can be restated as Dependency injection means providing an object with its instance variables by an external entity.…”

“…After completing the analysis of 20 open source projects, the authors have found no apparent correlation between the use of dependency injection and coupling and cohesion metrics. The authors of [23] provide a classification of four different kinds of dependency injection: constructor and method (setter) dependency injection with and without default implementation of an injected object.…”

“…[8], [23]) as an implementation of Dependency Inversion design principle [12] or, as Fowler [8] coined it, the Inversion of Control principle. Despite the industrial popularity of dependency injection, as witnessed by series of implementations and industry-oriented publications [8], [21], it has not deserved much attention inside the research community with exception of [14], [23], [16]. In [14], the authors analyze the impact of dependency injection on software maintainability metrics.…”

Dependency Injection with Static Analysis and Context-Aware Policy.

“…Yang et al [YTM08] empirically studied the prevalence of its use, and Razina and Janzen [RJ07] studied its impact on maintainability measures such as coupling and cohesion. DI has also been shown to be effective for configuring game components [PSC + 10] and connected with aspect-oriented programming [CI05], but there does not seem to be much other published research on dependency injection since Fowler [Fow04] provided its modern formulation.…”

“…In the last twenty years, dependency injection (DI) [Fow04,YTM08] has gained prominence as a design pattern for organizing the components of such a system, particularly in object-oriented programming environments.…”