Codehaus Parent
· The Codehaus is a collaborative environment for building open source projects with a strong emphasis on modern languages, focussed on quality components that meet real world needs.
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 codehaus-parent-4.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.