android-commons
· The aim of this library is to content the commons services, providers, API clients, ... for both Android applications. This library must not contain anything related with the presentation layer of Android (base activities, base fragments, custom views ...)
Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window android-commons-0.1.1.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.