Running XPath on child node

Question

I'm trying to do a xpath lookup on nodes returned by xpath lookup, but it doesn't seem to work as I expected.XPaths executed on the child nodes of a document seem to be executd against hthe root node of the document (in the example, the inventory tag.), instead of the root of the provided node.

Am I missing something here? I'm new to XPath.

Also, please don't answer "just do //book[author='Neal Stephenson'/title". I have a legitimate use case, and this is a simplified example.

Code snippet

DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance(); domFactory.setNamespaceAware(true); DocumentBuilder builder = domFactory.newDocumentBuilder(); Document doc = builder.parse("src/main/java/books.xml");  XPathFactory factory = XPathFactory.newInstance(); XPath xpath = factory.newXPath();  Node book = (Node) xpath.evaluate("//book[author='Neal Stephenson']", doc, XPathConstants.NODE); Node title = (Node) xpath.evaluate("/title", book, XPathConstants.NODE); // I get null here. Node inventory = (Node) xpath.evaluate("/inventory", book, XPathConstants.NODE); // this returns a node. 

book.xml

<inventory> <book year="2000">     <title>Snow Crash</title>     <author>Neal Stephenson</author>     <publisher>Spectra</publisher>     <isbn>0553380958</isbn>     <price>14.95</price> </book>  <book year="2005">     <title>Burning Tower</title>     <author>Larry Niven</author>     <author>Jerry Pournelle</author>     <publisher>Pocket</publisher>     <isbn>0743416910</isbn>     <price>5.99</price> </book>  <book year="1995">     <title>Zodiac</title>     <author>Neal Stephenson</author>     <publisher>Spectra</publisher>     <isbn>0553573862</isbn>     <price>7.50</price> </book>  <!-- more books... -->  </inventory> 

Answer 1

/foo will select based off of the root node, ignoring the context that you are evaluating the xpath against. foo (without the slash) is what you want; that selects based off of the current node.

https://www.w3schools.com/xml/xpath_syntax.asp gives a bit more info.

Answer 2

in Xpath, "." (Dot) represents the current document. So, write your XPATH string after a "." (Dot) .

ex :

"./title" 

or

".//title" 

Whatever you want....

removing the slash works only if its a child of the node. What if you want to use the // (wherever in the current Document) functionality ?

So, use the dot (.)

Thanks a lot for the above answers too :) .