private static final Logger ROOT = Logger.getLogger("");
    private static final Logger OAK = Logger.getLogger("oak");
    private static final Logger ELM = Logger.getLogger("elm");
    private static final Logger ELMER = Logger.getLogger("elm.er");

    public void sing() {
        ROOT.fine("Oh, I'm a lumberjack, and I'm okay.");
        OAK.fine("I sleep all night and I work all day.");
        ELM.fine("He's a lumberjack, and He's okay.");