Valid XML and DTD not validating

Question

I am trying to validate the following xml against the following DTD using the following Java code. (JDK 8 - All files are correctly found in the classpath). It is throwing the following exceptions.

Everything seems to be correct, and the IDE is not showing any red underlines when I embed the dtd in the xml, so I assume all syntax is correct. The error message says the exception is line number 1. When I add a blank line to the top of the DTD it changes that to line number 2, so I am pretty sure it is not liking the DTD. I tried the same using examples downloaded over the internet, and get the same issue.

What am I doing wrong???

test.xml:

<?xml version="1.0" encoding="UTF-8"?>
<properties>
    <property>key1=value1</property>
</properties>

test.dtd:

<!ELEMENT properties (property)*>
   <!ELEMENT property (#PCDATA)>

Validate.java:

public static void validateXml(String xmlFile, String dtdFile) 
    throws SAXException, IOException, ParserConfigurationException, URISyntaxException
{
    URL dtdUrl = XmlUtils.class.getClassLoader().getResource(dtdFile);
    System.out.println("DTD:\n" + new String(Files.readAllBytes(Paths.get(dtdUrl.toURI()))));

    // parse an XML document into a DOM tree
    DocumentBuilder parser = DocumentBuilderFactory.newInstance().newDocumentBuilder();
    URL xmlUrl = XmlUtils.class.getClassLoader().getResource(xmlFile);
    System.out.println("XML:\n" + new String(Files.readAllBytes(Paths.get(xmlUrl.toURI()))));

    Document document = parser.parse(xmlUrl.openStream());

    // create a SchemaFactory capable of understanding WXS schemas
    SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);

    // load a WXS schema, represented by a Schema instance
    Reader dtdReader = new URLReader(dtdUrl);
    Source schemaFile = new StreamSource(dtdReader);

    Schema schema = factory.newSchema(schemaFile);
    // create a Validator instance, which can be used to validate an instance document
    Validator validator = schema.newValidator();

    // validate the DOM tree
    validator.validate(new DOMSource(document));
}

System.out:

DTD:
<!ELEMENT properties (property)*>
        <!ELEMENT property (#PCDATA)>
XML:
<?xml version="1.0" encoding="UTF-8"?>
<properties>
    <property>key1=value1</property>
</properties>
Exception in thread "main" org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 3;
The markup in the document preceding the root element must be well-formed.
    at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper
    .createSAXParseException(ErrorHandlerWrapper.java:203)

score 1 · Accepted Answer · edited May 23 '17 at 10:34

1

You are trying to use your DTD as if it were an XML Schema (XSD). It's not an XML Schema, it's a DTD.

An XML Schema is itself an XML document. The error arises because your DTD cannot be parsed as an XML document and hence neither as an XML Schema.

See for example this answer for how to validate your XML document against a DTD.

edited May 23 '17 at 10:34

Community

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answered Sep 29 '16 at 20:07

Luke Woodward

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Valid XML and DTD not validating

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