Insert blank lines in jdom2 pretty printing

Question

I'm trying to simply add some blank lines to my jdom xml output. I've tried the following without luck:

Element root = new Element("root");
root.addContent(new CDATA("\n"));
root.addContent(new Text("\n"));

I figured the all-whitespace entry was being ignored so I tried creating my own XMLOutputProccessor like this:

class TweakedOutputProcessor extends AbstractXMLOutputProcessor {
    @Override
    public void process(java.io.Writer out, Format format, Text text) throws IOException {
        if ("\n".equals(text.getText())) {
            out.write("\n");
        } else {
            super.process(out, format, text);
        }
    }
}\

... called like this:

public static void printDocument(Document doc) {
    XMLOutputter xmlOutput = new XMLOutputter(new TweakedOutputProcessor());
    xmlOutput.setFormat(Format.getPrettyFormat());
    try {
            xmlOutput.output(doc, System.out);
    } catch (IOException e) { }
}

The unexpected thing here was that process(..., Text) was never called. After some experimentation I've found that process(..., Document) is being called, but none of the other process(..., *) methods are.

I also tried overriding the printText(...) and printCDATA(...) methods, but neither is being called -- even when the text is non-whitespace! Yet printElement(...) is being called.

So...

• What is going on here? What's doing the work if not these methods?
• How do I simply insert a blank line?

Answer 1

Use the XML xml:space="preserve" when setting values in the XML. JDOM honours that XML white space handling