Update XML attribute value in document tree

Question

I am not too sure why i cannot modify an attribute to my xml. The code below i used to get the read the attributes from the XML. Pulls the attributes without any issues.

        document = documentBuilder.parse(file);
        NodeList sessionNodelist = document.getElementsByTagName("session");
        if (sessionNodelist.getLength() > 0)
        {
            Element sessionElement = (Element) sessionNodelist.item(0);
            String timeout = sessionElement.getAttribute("timeout");
            String warning = sessionElement.getAttribute("warning");
        }

Now when i go to set them, it doesn't work and I am not too sure why. The code is below. it's the exact same code i used to pull the atribles, but instead of the getAttribute i used setAttribute which takes two parameters. setAttribute(String name, String Value).

        document = documentBuilder.parse(file);
        NodeList sessionNodelist = document.getElementsByTagName("session");
        if (sessionNodelist.getLength() > 0)
        {
            Element sessionElement = (Element) sessionNodelist.item(0);
            sessionElement.setAttribute("timeout","12");
            sessionElement.setAttribute("warning", "10");
        }

Any ideas?

What is expected here? The element attributes are being changed. Do you want to save them back in the XML? — M A
– M A, Commented Jan 8, 2015 at 19:34
Yes, my UI allows users to change the value, so I am setting the new value in the xml. — user1158745
– user1158745, Commented Jan 8, 2015 at 19:40
How are you verifying that the attributes were or were not changed? — ug_
– ug_, Commented Jan 8, 2015 at 19:45

M A · Accepted Answer · 2015-01-08 19:49:44Z

0

You need to write the document tree back to the XML file. See this page for how to write a DOM tree to a file.

You would use a javax.xml.transform.Transformer to write the object into the file as follows:

TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(document);
StreamResult result = new StreamResult(file);
transformer.transform(source, result);

answered Jan 8, 2015 at 19:49

M A

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1 Comment

user1158745 Over a year ago

Last question, for somereason when i go to write the file path it doesn't like the fact that there is a space within program files. Any way to get around this? I am using escape chars E.g "C:\\Progarm Files\\test.xml"

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