Context: During the last years, developers of mobile applications have the possibility to use new paradigms and tools for developing mobile applications. For instance, since 2017 Android developers have the official support to write Android applications using Kotlin language. Kotlin is programming language fully interoperable with Java that combines object-oriented and functional features. Objective: The goal of this paper is twofold. First, it aims to study the degree of adoption of Kotlin language on development of open-source Android applications and to measure the amount of Kotlin code inside Android applications. Secondly, it aims to measure the quality of Android applications that are written using Kotlin and to compare it with the quality of Android applications written using Java. Method: We first defined a method to detect Kotlin applications from a dataset of open-source Android applications. Then, we analyzed those applications to detect instances of code smells and computed an estimation of quality of the applications. Finally, we studied how the introduction of Kotlin code impacts on the quality of an Android application. Results: Our experiment found that 11.26 of applications from a dataset with 2,167 open-source applications have been written (partially or fully) using Kotlin language. We found that the introduction of Kotlin code increases the quality (in terms of presence of code smells) of the majority of the Android applications initially written in Java.
Therefore, @cite_2 and @cite_16 focused on code smells, but none of them investigated the presence of Android-specific smells during the software evolution. On the other hand, @cite_4 @cite_15 proposed a tool capable of identifying both type of smells, object-oriented, and Android and they evaluated the evolution of software quality.
@cite_15 @cite_16 @cite_4 @cite_2
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During last ten years, the number of smartphones and mobile applications has been constantly growing. Android, iOS and Windows Mobile are three mobile platforms that cover almost all smartphones in the world in 2017. Developing a mobile app involves first to choose the platforms the app will run, and then to develop specific solutions (i.e., native apps) for each chosen platform using platform-related toolkits such as Android SDK. A cross-platform mobile application is an app that runs on two or more mobile platforms. Several frameworks have been proposed to simplify the development of cross-platform mobile applications and to reduce development and maintenance costs. They are called cross-platform mobile app development frameworks. However, to our knowledge, the life-cycle and the quality of cross-platforms mobile applications built using those frameworks have not been studied in depth. Our main goal is to first study the processes of development and maintenance of mobile applications built using cross-platform mobile app development frameworks, focusing particularly on the bug-fixing activity. Then, we aim at defining tools for automated repairing bugs from cross-platform mobile applications. The evolution rate of mobile applications is much higher than regular software applications having shorter release deadlines and smaller code base. Mobile applications tend to be evolved quickly by developers to meet several new customer requirements and fix discovered bugs. However, evolving the existing features and design may introduce bad design practices, also called code smells, which can highly decrease the maintainability and performance of these mobile applications. However, unlike the area of object-oriented software systems, the detection of code smells in mobile applications received a very little of attention. Recent, few studies defined a set of quality metrics for Android applications and proposed a support to manually write a set of rules to detect code smells by combining these quality metrics. However, finding the best combination of metrics and their thresholds to identify code smells is left to the developer as a manual process. In this paper, we propose to automatically generate rules for the detection of code smells in Android applications using a multi-objective genetic programming algorithm (MOGP). The MOGP algorithm aims at finding the best set of rules that cover a set of code smell examples of Android applications based on two conflicting objective functions of precision and recall. We evaluate our approach on 184 Android projects with source code hosted in GitHub. The statistical test of our results show that the generated detection rules identified 10 Android smell types on these mobile applications with an average correctness higher than 82 and an average relevance of 77 based on the feedback of active developers of mobile apps. There has been tremendous growth in the use of mobile devices over the last few years. This growth has fueled the development of millions of software applications for these mobile devices often called as 'apps'. Current estimates indicate that there are hundreds of thousands of mobile app developers. As a result, in recent years, there has been an increasing amount of software engineering research conducted on mobile apps to help such mobile app developers. In this paper, we discuss current and future research trends within the framework of the various stages in the software development life-cycle: requirements (including non-functional), design and development, testing, and maintenance. While there are several non-functional requirements, we focus on the topics of energy and security in our paper, since mobile apps are not necessarily built by large companies that can afford to get experts for solving these two topics. For the same reason we also discuss the monetizing aspects of a mobile app at the end of the paper. For each topic of interest, we first present the recent advances done in these stages and then we present the challenges present in current work, followed by the future opportunities and the risks present in pursuing such research. In past and recent years, the issues related to managing technical debt received significant attention by researchers from both industry and academia. There are several factors that contribute to technical debt. One of these is represented by code bad smells, i.e., symptoms of poor design and implementation choices. While the repercussions of smells on code quality have been empirically assessed, there is still only anecdotal evidence on when and why bad smells are introduced. To fill this gap, we conducted a large empirical study over the change history of 200 open source projects from different software ecosystems and investigated when bad smells are introduced by developers, and the circumstances and reasons behind their introduction. Our study required the development of a strategy to identify smell-introducing commits, the mining of over 0.5M commits, and the manual analysis of 9,164 of them (i.e., those identified as smell-introducing). Our findings mostly contradict common wisdom stating that smells are being introduced during evolutionary tasks. In the light of our results, we also call for the need to develop a new generation of recommendation systems aimed at properly planning smell refactoring activities.