Android Code Smells: From Introduction to Refactoring

TL;DR

This paper presents a large-scale empirical study on Android code smells, analyzing their introduction, evolution, and removal, revealing insights into developer practices and the nature of mobile-specific code smells.

Contribution

It provides the first comprehensive empirical analysis of Android code smells, including their lifecycle and developer behaviors, based on data from 324 apps and developer discussions.

Findings

Mobile-specific code smells are widespread and not solely due to release pressure.

Developers often remove code smells as a side effect of maintenance, not targeted refactoring.

Many code smells persist despite developer awareness, indicating challenges in refactoring.

Abstract

Object-oriented code smells are well-known concepts in software engineering that refer to bad design and development practices commonly observed in software systems. With the emergence of mobile apps, new classes of code smells have been identified by the research community as mobile-specific code smells. These code smells are presented as symptoms of important performance issues or bottlenecks. Despite the multiple empirical studies about these new code smells, their diffuseness and evolution along change histories remains unclear. We present in this article a large-scale empirical study that inspects the introduction, evolution, and removal of Android code smells. This study relies on data extracted from 324 apps, a manual analysis of 561 smell-removing commits, and discussions with 25 Android developers. Our findings reveal that the high diffuseness of mobile-specific code smells is not a result of releasing pressure. We also found that the removal of these code smells is generally a side effect of maintenance activities as developers do not refactor smell instances even when they are aware of them.