public AbstractDemo() 
{

}

 protected XMLWriter createXMLWriter() throws Exception 
{
        return new XMLWriter(System.out, format);
}

A Factory Method to create an XMLWriter instance allowing derived classes to change this behaviour

 protected XMLWriter getXMLWriter() throws Exception 
{
        if (writer == null) {
            writer = createXMLWriter();
        }
        return writer;
}

 protected Document parse(String xmlFile) throws Exception 
{
        throw new RuntimeException(
                "parse(String xmlFile) not implemented in this demo");
}

 protected  void print(String text) 
{
        System.out.print(text);
}

 protected  void printUsage(String text) 
{
        println("Usage: java " + getClass().getName() + " " + text);
}

 protected  void println(String text) 
{
        System.out.println(text);
}

 protected  void process(Document document) throws Exception 
{
        getXMLWriter().write(document);
        getXMLWriter().flush();
}

 public  void run(String[] args) throws Exception 
{
        if (args.length <  1) {
            printUsage("no XML document URL specified");
            return;
        }
        int idx = format.parseOptions(args, 0);
        if (idx  >= args.length) {
            printUsage("no XML document URL specified");
            return;
        } else {
            writer = createXMLWriter();
            Document document = parse(args[idx]);
            process(document);
        }
}

 protected static  void run(AbstractDemo demo,
    String[] args) 
{
        try {
            demo.run(args);
        } catch (DocumentException e) {
            System.out.println("Exception occurred: " + e);
            Throwable nestedException = e.getNestedException();
            if (nestedException != null) {
                System.out.println("NestedException: " + nestedException);
                nestedException.printStackTrace();
            } else {
                e.printStackTrace();
            }
        } catch (Throwable t) {
            System.out.println("Exception occurred: " + t);
            t.printStackTrace();
        }
}