Do android developers neglect error handling? a maintenance-Centric study on the relationship between android abstractions and uncaught exceptions

摘要

All the mainstream programming languages in widespread use for mobile app development provide error handling mechanisms to support the implementation of robust apps. Android apps, in particular, are usually written in the Java programming language. Java includes an exception handling mechanism that allows programs to signal the occurrence of errors by throwing exceptions and to handle these exceptions by catching them. All the Android-specific abstractions, such as activities and asynctasks, can throw exceptions when errors occur. When an app catches the exceptions that it or the libraries upon which it depends throw, it can resume its activity or, at least, fail in a graceful way. On the other hand, uncaught exceptions can lead an app to crash, particularly if they occur within the main thread. Previous work has shown that, in real Android apps available at the Play Store, uncaught exceptions thrown by Android-specific abstractions often cause these apps to fail. This paper presents an empirical study on the relationship between the usage of Android abstractions and uncaught exceptions. Our approach is quantitative and maintenance-centric. We analyzed changes to both normal and exception handling code in 112 versions extracted from 16 software projects covering a number of domains, amounting to more than 3 million LOC. Change impact analysis and exception flow analysis were performed on those versions of the projects. The main finding of this study is that, during the evolution of the analyzed apps, an increase in the use of Android abstractions exhibits a positive and statistically significant correlation with the number of uncaught exception flows. Since uncaught exceptions cause apps to crash, this result suggests that these apps are becoming potentially less robust as a consequence of exception handling misuse. Analysis of multiple versions of these apps revealed that Android developers usually employ abstractions that may throw exceptions without adding the appropriate handlers for these exceptions. This study highlights the need for better testing and verification tools with a focus on exception handling code and for a change of culture in Android development or, at least, in the design of its APIs.