Java XML parsing - Recursively find element

Question

I have an XML but all I know is the name of the element I want to find the value of. That is, I can't use XPath to easily retrieve the element. I have to recursively work my way through the XML which I seem to fail. What I've tried is:

Assume an XML of the following structure:

<Store id="1">
  ...
  <Customer>
    <CustomerId>123</CustomerId>
  </Customer>
</Store>

I want to get the value of the CustomerId tag. In reality, I don't know where in the XML my CustomerId tag is. I tried the following recursion:

private String parseXmlForCustomerId(Element element) {
    if (element.getNodeName().equals("CustomerId")) {
        return element.getTextContent();
    }
    NodeList children = element.getChildNodes();
    for (int i = 0; i < children.getLength(); i++) {
        Node node = children.item(i);
        if (node.getNodeType() == Node.ELEMENT_NODE && parseXmlForCustomerId((Element) node).equals("CustomerId")) {
            return node.getTextContent();
        }
    }
    return "";
}

What have I done wrong?

Thanks in advance!

Why can't you use xpath? //CustomerId seems fine.

daniu
– daniu

2018-01-10 14:39:38 +00:00
Commented Jan 10, 2018 at 14:39 — daniu
– daniu, Commented Jan 10, 2018 at 14:39
Oh didn't know that! Will try!

Richard Silvertass
– Richard Silvertass

2018-01-10 14:44:53 +00:00
Commented Jan 10, 2018 at 14:44 — Richard Silvertass
– Richard Silvertass, Commented Jan 10, 2018 at 14:44

daniu · Accepted Answer · 2018-01-10 14:52:40Z

2

Xpath should work using

XPathExpression expr = xpath.compile("//CustomerId");
NodeList nl = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);

answered Jan 10, 2018 at 14:52

daniu

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Comments

Joop Eggen · Accepted Answer · 2018-01-10 14:48:14Z

0

    if (node.getNodeType() == Node.ELEMENT_NODE
            && parseXmlForCustomerId((Element) node).equals("CustomerId")) {
        return node.getTextContent();
    }

should be:

    if (node.getNodeType() == Node.ELEMENT_NODE) {
        String found = parseXmlForCustomerId((Element) node);
        if (!found.isEmpty()) {
            return found;
        }
    }

However XPath is possible.

answered Jan 10, 2018 at 14:48

Joop Eggen

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Comments

subin · Accepted Answer · 2018-01-10 14:51:48Z

Wrote a reusable method to parse TagValue from xmlRecords based on nodeTagName.

public String parseXMLwithNodeTagNames(String xmlRecords, String nodeTagName) {
        String tagValue = "";
        try {
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = dbf.newDocumentBuilder();
            Document doc = null;
            String s = new String(xmlRecords.getBytes(), "ISO-8859-1");
            doc = db.parse(new InputSource(new StringReader(s)));
            NodeList nl = doc.getElementsByTagName(nodeTagName);
            if (nl != null) {
                for (int i = 0; i < nl.getLength(); i++) {
                    Node item = nl.item(i);
                    String name = item.getNodeName();
                    tagValue = item.getTextContent();

                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return tagValue;

    }

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