Snippet for running Apache Xerces (Java version) to validate XML files with catalog and schema support

catalog.xml

<?xml version="1.0"?>
<!DOCTYPE catalog PUBLIC "-//OASIS//DTD XML Catalogs V1.0//EN"
  "file:///usr/share/xml/schema/xml-core/catalog.dtd">
<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog" prefer="public">
    <uri name="http://www.sitemaps.org/schemas/sitemap/0.9" 
         uri="sitemap.xsd"/>
    <uri name="http://www.google.com/schemas/sitemap-news/0.9"
         uri="sitemap-news.xsd"/>
</catalog>

demo.xml

<?xml version="1.0" encoding="UTF-8"?>
<urlset
    xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" 
    xmlns:news="http://www.google.com/schemas/sitemap-news/0.9">
<url>
    <loc>URL-ZUM-ARTIKEL</loc>
    <news:news>
        <news:publication>
            <news:name>BEZEICHNUNG MEINER SEITE</news:name>
            <news:language>de</news:language>
        </news:publication>
        <news:genres>PressRelease</news:genres>
        <news:publication_date>2012-08-28T08:00:00+02:00</news:publication_date>
        <news:title>TITEL DES ARTIKELS</news:title>
        <news:keywords>tag1, tag2, tag3, tag4, tag5</news:keywords>
    </news:news>
</url>
</urlset>

SchemaValidator.java

import java.io.File;
import javax.xml.XMLConstants;
import javax.xml.transform.Source;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.*;
import org.xml.sax.SAXException;
import com.sun.org.apache.xerces.internal.util.XMLCatalogResolver;

public class SchemaValidator
{
        public void run() throws Exception
        {
                Source xmlFile = new StreamSource(new File("demo.xml"));
                SchemaFactory schemaFactory = SchemaFactory.newInstance(
                        XMLConstants.W3C_XML_SCHEMA_NS_URI);

                String[] catalogs = { "catalog.xml" };

                XMLCatalogResolver resolver
                        = new XMLCatalogResolver(catalogs, true);
                schemaFactory.setResourceResolver(resolver);                        

                Schema schema = schemaFactory.newSchema();                
                
                Validator validator = schema.newValidator();
                validator.setResourceResolver(
                        schemaFactory.getResourceResolver());

                try {
                        validator.validate(xmlFile);
                        System.out.println(xmlFile.getSystemId()
                                + " is valid");
                } catch (SAXException e) {
                        System.out.println(xmlFile.getSystemId()
                                + " is NOT valid");
                        System.out.println("Reason: "
                                + e.getLocalizedMessage());
                }
        }

        public static void main(String[] args)
        {        
                SchemaValidator app = new SchemaValidator();
                
                try {
                        app.run();
                } catch (Exception e) {
                        System.out.println(e);
                }
        }
}

Hi,
I was trying out your snippet but it fails with this error: "org.xml.sax.SAXParseException; lineNumber: 4; columnNumber: 65; cvc-elt.1: Cannot find the declaration of element 'urlset'."

Don't know if I have to do something else than downloading the two xsd from google and put them on my classpath.

If you got this working I would really like to know how.

Thanks,
Angelo