根据模式验证XML-找不到元素的声明

Question

I am quite new to XML validation so sorry for the elementary question. I have the following document:

<tincan xmlns="http://projecttincan.com/tincan.xsd">
  <activities>
    <activity id="TestActivity" type="course">
      <name lang="und">MyCourse</name>
      <description lang="und"/>
      <launch lang="und">start.html</launch>
    </activity>
    <activity id="p001" type="objective">
      <name lang="und">First Page</name>
      <description lang="und">First Page</description>
    </activity>
  </activities>
</tincan>

I am trying to validate it against the following schema: http://projecttincan.com/tincan.xsd (I also tried removing the schema from my XML and providing it externally).

I always get the following exception: cvc-elt.1: Cannot find the declaration of element 'tincan'

By looking into the schema, I see that the tincan element is defined there and it is also present in my XML so I don't udnerstand what is the source of this exception. I would be glad if someone could explain how the validation is supposed to work.

EDIT: My code for the validation:

DocumentBuilder parser = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document document = parser.parse(stream);

// 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
Source schemaFile = new StreamSource(getClass().getClassLoader().getResource("tincan.xsd").getFile());
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));

EDIT2: Schema was linked here but I will post it here again for clarity:

<xs:schema xmlns="http://projecttincan.com/tincan.xsd" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:tc="http://projecttincan.com/tincan.xsd" targetNamespace="http://projecttincan.com/tincan.xsd" elementFormDefault="qualified">
<xs:element name="tincan" type="tincan"></xs:element>
<xs:complexType name="tincan">
<xs:sequence>
<xs:element name="activities" type="activities" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="activity">
<xs:sequence>
<xs:element name="name" type="langstring" maxOccurs="unbounded"/>
<xs:element name="description" type="langstring" maxOccurs="unbounded"/>
<xs:element name="launch" type="langURI" maxOccurs="unbounded" minOccurs="0"/>
<xs:element name="resource" type="langURI" maxOccurs="unbounded" minOccurs="0"/>
<xs:element name="interactionType" type="xs:string" minOccurs="0"/>
<!--  CMI Interaction fields  -->
<xs:element name="correctResponsePatterns" type="correctResponsePatternList" minOccurs="0"/>
<xs:element name="choices" type="interactionComponentList" minOccurs="0"/>
<xs:element name="scale" type="interactionComponentList" minOccurs="0"/>
<xs:element name="source" type="interactionComponentList" minOccurs="0"/>
<xs:element name="target" type="interactionComponentList" minOccurs="0"/>
<xs:element name="steps" type="interactionComponentList" minOccurs="0"/>
<!--  Extensions -->
<xs:element name="extensions" type="extensions" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="id" type="xs:anyURI"/>
<xs:attribute name="type" type="xs:string"/>
</xs:complexType>
<xs:complexType name="activities">
<xs:sequence>
<xs:sequence>
<xs:element name="activity" type="activity" maxOccurs="unbounded"/>
<xs:element name="provider" type="provider" minOccurs="0"/>
</xs:sequence>
</xs:sequence>
</xs:complexType>
<xs:complexType name="provider">
<xs:all>
<xs:element name="name" type="langstring"/>
<xs:element name="id" type="xs:string"/>
<xs:element name="secret" type="xs:string" minOccurs="0"/>
<xs:element name="public_key" type="xs:string" minOccurs="0"/>
<xs:element name="info" type="xs:anyURI" minOccurs="0"/>
</xs:all>
</xs:complexType>
<xs:complexType name="correctResponsePatternList">
<xs:sequence>
<xs:element name="correctResponsePattern" type="xs:string" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="interactionComponentList">
<xs:sequence>
<xs:element name="component" type="interactionComponentType" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="interactionComponentType">
<xs:sequence>
<xs:element name="id" type="xs:string"/>
<xs:element name="description" type="langstring" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="langstring">
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute name="lang" type="xs:language"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="extensions">
<xs:sequence>
<xs:element name="extension" type="extension" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="extension">
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute name="key" type="xs:string" use="required"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="langURI">
<xs:simpleContent>
<xs:extension base="xs:anyURI">
<xs:attribute name="lang" type="xs:language"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:schema>

Answer 1

Make your document builder "namespaceAware" should fix it!

  DocumentBuilderFactory f=DocumentBuilderFactory.newInstance();          
  f.setNamespaceAware(true);

You can also operate directly on a Source object, which makes code a little bit shorter, it's also likely to be faster and use less memory.

Sample with both variants

package stack43324079;

import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Source;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import javax.xml.validation.Validator;

import org.junit.Test;
import org.w3c.dom.Document;

public class HowToValidateXml {
    @Test
    public void validate1() throws Exception {
        DocumentBuilderFactory f=DocumentBuilderFactory.newInstance();
        f.setNamespaceAware(true);
        DocumentBuilder parser = f.newDocumentBuilder();
        Document document = parser.parse(Thread.currentThread().getContextClassLoader().getResourceAsStream("43324079.xml"));
        SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
        Source schemaFile = new StreamSource(Thread.currentThread().getContextClassLoader().getResourceAsStream("tincan.xsd"));
        Schema schema = factory.newSchema(schemaFile);
        Validator validator = schema.newValidator();
        validator.validate(new DOMSource(document));
    }

    @Test
    public void validate2() throws Exception {
        Source xmlFile = new StreamSource(Thread.currentThread().getContextClassLoader().getResourceAsStream("43324079.xml"));
        SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
        Schema schema = factory.newSchema(Thread.currentThread().getContextClassLoader().getResource("tincan.xsd"));
        Validator validator = schema.newValidator();
        validator.validate(xmlFile);
    }
}

Answer 2

You're not showing us the schema, so we can only guess what's wrong, but my guess would be that the element is declared in the wrong namespace.

If that's a wrong guess, then try to remember next time you ask a question that it's very hard to find bugs in code when people don't show you the code.