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 nd4j-jcublas-osx-6.0-0.0.3.5.5.2.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.
