How can I properly parse this XML file with xPath in Java?

Question

This is my XML file that I need to parse:

<?xml version="1.0"?>
<catalog>
   <book id="bk101">
      <author>Gambardella, Matthew</author>
      <title>XML Developer's Guide</title>
      <genre>Computer</genre>
      <price>44.95</price>
      <publish_date>2000-10-01</publish_date>
      <description>An in-depth look at creating applications 
      with XML.</description>
   </book>
   <book id="bk102">
      <author>Ralls, Kim</author>
      <title>Midnight Rain</title>
      <genre>Fantasy</genre>
      <price>5.95</price>
      <publish_date>2002-12-16</publish_date>
      <description>A former architect battles corporate zombies, 
      an evil sorceress, and her own childhood to become queen 
      of the world.</description>
   </book>
   <book id="bk103">
      <author>Corets, Eva</author>
      <title>Maeve Ascendant</title>
      <genre>Fantasy</genre>
      <price>5.95</price>
      <publish_date>2000-11-17</publish_date>
      <description>After the collapse of a nanotechnology 
      society in England, the young survivors lay the 
      foundation for a new society.</description>
   </book>
   <book id="bk104">
      <author>Corets, Eva</author>
      <title>Oberon's Legacy</title>
      <genre>Fantasy</genre>
      <price>5.95</price>
      <publish_date>2001-03-10</publish_date>
      <description>In post-apocalypse England, the mysterious 
      agent known only as Oberon helps to create a new life 
      for the inhabitants of London. Sequel to Maeve 
      Ascendant.</description>
   </book>
   <book id="bk105">
      <author>Corets, Eva</author>
      <title>The Sundered Grail</title>
      <genre>Fantasy</genre>
      <price>5.95</price>
      <publish_date>2001-09-10</publish_date>
      <description>The two daughters of Maeve, half-sisters, 
      battle one another for control of England. Sequel to 
      Oberon's Legacy.</description>
   </book>
   <book id="bk106">
      <author>Randall, Cynthia</author>
      <title>Lover Birds</title>
      <genre>Romance</genre>
      <price>4.95</price>
      <publish_date>2003-09-02</publish_date>
      <description>When Carla meets Paul at an ornithology 
      conference, tempers fly as feathers get ruffled.</description>
   </book>
   <book id="bk107">
      <author>Thurman, Paula</author>
      <title>Splish Splash</title>
      <genre>Romance</genre>
      <price>4.95</price>
      <publish_date>2004-11-02</publish_date>
      <description>A deep sea diver finds true love twenty 
      thousand leagues beneath the sea.</description>
   </book>
   <book id="bk108">
      <author>Knorr, Stefan</author>
      <title>Creepy Crawlies</title>
      <genre>Horror</genre>
      <price>4.95</price>
      <publish_date>2005-12-06</publish_date>
      <description>An anthology of horror stories about roaches,
      centipedes, scorpions  and other insects.</description>
   </book>
   <book id="bk109">
      <author>Kress, Peter</author>
      <title>Paradox Lost</title>
      <genre>Science Fiction</genre>
      <price>6.95</price>
      <publish_date>2006-11-02</publish_date>
      <description>After an inadvertant trip through a Heisenberg
      Uncertainty Device, James Salway discovers the problems 
      of being quantum.</description>
   </book>
   <book id="bk110">
      <author>O'Brien, Tim</author>
      <title>Microsoft .NET: The Programming Bible</title>
      <genre>Computer</genre>
      <price>36.95</price>
      <publish_date>2006-12-09</publish_date>
      <description>Microsoft's .NET initiative is explored in 
      detail in this deep programmer's reference.</description>
   </book>
   <book id="bk111">
      <author>O'Brien, Tim</author>
      <title>MSXML3: A Comprehensive Guide</title>
      <genre>Computer</genre>
      <price>36.95</price>
      <publish_date>2007-12-01</publish_date>
      <description>The Microsoft MSXML3 parser is covered in 
      detail, with attention to XML DOM interfaces, XSLT processing, 
      SAX and more.</description>
   </book>
   <book id="bk112">
      <author>Galos, Mike</author>
      <title>Visual Studio 7: A Comprehensive Guide</title>
      <genre>Computer</genre>
      <price>49.95</price>
      <publish_date>2008-04-16</publish_date>
      <description>Microsoft Visual Studio 7 is explored in depth,
      looking at how Visual Basic, Visual C++, C#, and ASP+ are 
      integrated into a comprehensive development 
      environment.</description>
   </book>
</catalog>

I want to show every book and its information that has a publish date after 2005. and the price is bigger than 10. This is my Java code:

package xml;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;

public class Main {

    public static void main(String[] args) throws XPathExpressionException, FileNotFoundException {

        XPathFactory factory = XPathFactory.newInstance();
        XPath xPath = factory.newXPath();

        XPathExpression xPathExpression = xPath.compile("catalog/book[publish_date>2005]/price | catalog/book[price>10]/price");

        File xmlDocument = new File("Books.xml");
        InputSource inputSource = new InputSource(new FileInputStream(xmlDocument));

        Object result = xPathExpression.evaluate(inputSource, XPathConstants.NODESET);

        NodeList nodeList = (NodeList)result;

        for (int i = 0; i < nodeList.getLength(); i++) {
            System.out.println("Info: " + nodeList.item(i).getFirstChild().getNodeValue());
        }

    }

}

How should I do this properly with this query?

Adding Lorem ipsum so the question can post: Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.

Answer 1

You almost have it right. The problem is that, according the specification, a numeric comparison ( < or > ) requires implicitly converting each operand to a number. A node's text content is only a valid number if it consists entirely of ASCII digits, with an optional leading minus, optional period, and optional surrounding whitespace.

A date like 2002-12-16 obviously does not qualify. However, you can turn that into a string that can be implicitly converted into a number, using substring-before :

XPathExpression xPathExpression = xPath.compile(
    "catalog/book[substring-before(publish_date,'-')>2005 and price>10]/price");

Answer 2

Take advantage of the XML date format and do a string comparison there, annd combine your conditions

/catalog/book[(publish_date > '2005') and (number(price) > 10)]

And thus

XPathExpression xPathExpression = xPath.compile("/catalog/book[(publish_date > '2005') and (number(price) > 10)]");
NodeList bookNodes = (NodeList)xPathExpression.evaluate(inputSource, XPathConstants.NODESET);
for (int i = 0; i < bookNodes.getLength(); i++) {
    Element bookElement = bookNodes.item(i);
    System.out.println("Author: " + bookElement.getElementsByTagName("author").item(0).getNodeValue());
}

You'll need to add the remaining, necessary tags. Also, if you book elements might no all contain all expected node, you'll need to check the collection returned by getElementsByTagName()