  Continuous Integration (CI) and Continuous Delivery (CD) have been
demonstrated to be effective in facilitating software building, testing, and
deployment. Many research studies have investigated and subsequently improved
their working processes. Unfortunately, such research efforts have largely not
touched on the usage of CI/CD in the development of Android apps. We fill this
gap by conducting an exploratory study of CI/CD adoption in open-source Android
apps. We start by collecting a set of 84,475 open-source Android apps from the
most popular three online code hosting sites, namely Github, GitLab, and
Bitbucket. We then look into those apps and find that (1) only around 10\% of
apps have leveraged CI/CD services, i.e., the majority of open-source Android
apps are developed without accessing CI/CD services, (2) a small number of apps
(291) has even adopted multiple CI/CD services, (3) nearly half of the apps
adopted CI/CD services have not really used them, and (4) CI/CD services are
useful to improve the popularity of projects.
