how to update xml using xPath

Question

i have the following xml file:

<?xml version='1.0' encoding='utf-8' ?>
<osm>
<node id="25779111" lat="50.03342" lon="5.461545"/>
<node id="25779112" lat="50.03304" lon="5.814"/>
<node id="25779119" lat="50.03395" lon="5.8255"/>
<tag k="maxspeed" v="30"/>
<tag k="maxspeed:zone" v="yes"/>
<ele k="maxspeed:zone" v="60"/>

and i reviewed some posts to know how can i update or change a value in the xml file using xpath, and idid the following :

for (int i = 1 ; i <= 2; i++) {
    String expr0 = "//node[@lat='53.0334062'][@lon='8.8461545']/following-sibling::tag["+i+"]/@v";
    xPath.compile(expr0);
    Node s = (Node) xPath.evaluate(expr0, document, XPathConstants.NODE);
    System.out.println(s);

    s.setNodeValue("999");
}

but when i checked the xml file, i expected to see the change written to it, but there was no change. please let me know how to change the value in the xml file using xPath correctly.

Maybe this post could help you? http://stackoverflow.com/questions/6124239/how-to-update-xml-using-xpath-and-java — Smudoo, Aug 13 '15 at 14:12
Did you write the file back to disk? Otherwise, it sounds like you only modified the DOM (in-memory representation of the document). — FatalError, Aug 13 '15 at 14:21
@FatalError can u give me an example how to write that value back on the file using xpath? — rmaik, Aug 13 '15 at 14:31

score 0 · Answer 1 · answered Aug 29 '15 at 08:12

you need to write the document back to the disk. Here's how:

  TransformerFactory transformerFactory = TransformerFactory.newInstance();
  Transformer transformer = transformerFactory.newTransformer();
  DOMSource source = new DOMSource(document);
  String filePath = "path/to/new/file.xml";
  StreamResult streamResult =  new StreamResult(new File(filePath));
  transformer.transform(source, streamResult);

More help here: http://download.oracle.com/javaee/1.4/tutorial/doc/JAXPXSLT4.html

Hope this helps. :)

how to update xml using xPath

1 Answers1