JDom How to comment an existing line

Question

I am currently struggling to comment an existing line with JDom, best I would like to comment an entire node.

    SAXBuilder jdomBuild = new SAXBuilder();
    jdomDoc = jdomBuild.build(fileLocation);
    Element root = jdomDoc.getRootElement();
    Element header = root.getChild("header_info")
    // how can I comment the lines now?

And the document :

<xml_report>

    <header_info>
        <bla1></bla1>
        <bla2></bla2>
        <bla3></bla3>
        <bla4></bla4>
        <bla5></bla5>
        <bla6></bla6>
    </header_info>

    <random_things>
        <random></random>
    </random_things>

</xml_report>

I would like to comment the whole header but I can't find the solution anywhere...

Could I have some advice and explainations please?

Answer 1

Replace the header element with a Comment containing the content of the element. Example:

XMLOutputter outputter = new XMLOutputter();
outputter.getFormat().setExpandEmptyElements(true);
SAXBuilder jdomBuild = new SAXBuilder();
Document jdomDoc = jdomBuild.build(new ByteArrayInputStream(("<xml_report>\n"
        + "\n"
        + "    <header_info>\n"
        + "        <bla1></bla1>\n"
        + "        <bla2></bla2>\n"
        + "        <bla3></bla3>\n"
        + "        <bla4></bla4>\n"
        + "        <bla5></bla5>\n"
        + "        <bla6></bla6>\n"
        + "    </header_info>\n"
        + "\n"
        + "    <random_things>\n"
        + "        <random/>\n"
        + "    </random_things>\n"
        + "\n"
        + "</xml_report>").getBytes(StandardCharsets.UTF_8)));
Element root = jdomDoc.getRootElement();
Element header = root.getChild("header_info");
Comment comment = new Comment(outputter.outputString(header));
root.setContent(root.indexOf(header), comment);
outputter.output(jdomDoc, System.out);

Output:

<?xml version="1.0" encoding="UTF-8"?>
<xml_report>

    <!--<header_info>
        <bla1></bla1>
        <bla2></bla2>
        <bla3></bla3>
        <bla4></bla4>
        <bla5></bla5>
        <bla6></bla6>
    </header_info>-->

    <random_things>
        <random></random>
    </random_things>

</xml_report>

Note that you cannot preserve the fromatting with JDOM for every possible input, since the formatting information is removed during the parsing.

Also note that you cannot put a comment around a block containing a comment, since this would end the comment sooner. In fact JDOM does not allow -- to occur as substring in a comment. You could simply break up those substings inside comments using

private static final Pattern PATTERN = Pattern.compile("-{2,}"); 

private static String fix(String string) {
    StringBuilder sb = new StringBuilder();
    Matcher m = PATTERN.matcher(string);
    int lastEnd = 0;
    while (m.find()) {
        System.out.println(m.group());
        sb.append(string.subSequence(lastEnd, m.start())).append('-');
        lastEnd = m.end();
        for (int i = lastEnd - m.start(); i > 1; i--) {
            sb.append(" -");
        }
    }
    if (lastEnd < string.length()) {
        sb.append(string.subSequence(lastEnd, string.length()));
    }
    return sb.toString();
}

Comment comment = new Comment(fix(outputter.outputString(header)));

Anything else would get compicated, since you'd need to take <![CDATA[]]> into account too.