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-macosx-x86_64-cuda-8_0-0.8.0.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.
