how to get the child node value on attribute stax Java

Question

I need guidance in STAX java I have xml file, I need to get the inner element value prior satisfying previous parent node book id attribute value. For example.

<books>
<book id = "1">
   <chap num ="1"> This First Title </chap>
   <chap num ="2"> This second of first book </chap>
</book>
<book id = "2">
   <chap num ="1"> This First Title of second book </chap>
   <chap num = "2"> This Second of second book </chap>
</book>
</books>

I need the values of attribute from "chap" element based on comparing on of the book attribute id.

Just hint would guide me.

Answer 1

You would need to do something along these lines

String xmlString = ...
DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
Document doc = docBuilder.parse(xmlString);

XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();
String xpathExp = "/books/book[@id=\"2\"]";
Node node = (Node) xpath.evaluate(xpathExp, doc, XPathConstants.NODE);

From the "book" node, you can loop over the children ("chap" nodes). Or you can access the list of child nodes directly by:

String xpathExp = "/books/book[@id=\"2\"]/chap";
NodeList chapNodeList = (NodeList) xpath.evaluate(xpathExp, doc, XPathConstants.NODESET);

You can then retrieve the attribute values from the "chap" nodes. (example, node.getTextContent();)

Or if you know which chapter you want, modify the xpath expression to be more specific.