Marshalling HashMap with JAXB 2.0 - empty tags & ill schema

Question

Hi all,
I expected JAXB 2.0 to be capable to handle basic classes like HashMap, but it does not look so. I have two classes: SimpleNegotiationManager which has a property HashMap in which are stored the instances of SimpleInitiatedConversation:
package xml;
import javax.xml.bind.annotation.*;
import java.util.HashMap;
@XmlAccessorType(AccessType.FIELD)
@XmlRootElement
public class SimpleNegotiationManager {
    @XmlElement
    protected HashMap<String, SimpleInitiatedConversation> initiatedConversations;
    public SimpleNegotiationManager() {
    public HashMap<String, SimpleInitiatedConversation> getInitiatedConversations() {
        if (initiatedConversations == null) {
            initiatedConversations = new HashMap();
        return initiatedConversations;
    public void setInitiatedConversations(HashMap<String, SimpleInitiatedConversation> initiatedConversations) {
        this.initiatedConversations = initiatedConversations;
}and
package xml;
import javax.xml.bind.annotation.*;
import java.util.ArrayList;
import java.util.List;
@XmlAccessorType(AccessType.FIELD)
@XmlType
public class SimpleInitiatedConversation {
    @XmlElement
    protected List<String> messages;
    protected String conversationID;
    protected int protocolState;
    public SimpleInitiatedConversation() {
    public List<String> getMessages() {
        if (messages == null) {
            messages = new ArrayList();
        return messages;
    public void setMessages(List<String> messages) {
        this.messages = messages;
    public int getProtocolState() {
        return protocolState;
    public void setProtocolState(int protocolState) {
        this.protocolState = protocolState;
    public String getConversationID() {
        return conversationID;
    public void setConversationID(String conversationID) {
        this.conversationID = conversationID;
}When I marshalled SimpleNegotiationManager while the HashMap was filled with several <String,SimpleInitiatedConversation> entries, in the output were empty tags initiatedConversations:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<simpleNegotiationManager>
  <initiatedConversations>
  </initiatedConversations>
</simpleNegotiationManager>When I used schemagen to generate a schema, it produced:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<xs:schema version="1.0" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:complexType name="simpleInitiatedConversation">
    <xs:sequence>
      <xs:element name="messages" type="xs:string" maxOccurs="unbounded" minOccurs="0"/>
      <xs:element name="conversationID" type="xs:string" minOccurs="0"/>
      <xs:element name="protocolState" type="xs:int"/>
    </xs:sequence>
  </xs:complexType>
  <xs:element name="simpleNegotiationManager" type="simpleNegotiationManager"/>
  <xs:complexType name="simpleNegotiationManager">
    <xs:sequence>
      <xs:element name="initiatedConversations" type="hashMap" minOccurs="0"/>
    </xs:sequence>
  </xs:complexType>
  <xs:complexType name="hashMap">
    <xs:complexContent>
      <xs:extension base="abstractMap">
        <xs:sequence/>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>
  <xs:complexType name="abstractMap" abstract="true"/>
</xs:schema>Particularly the description of HashMap seems ill - there is not specified that the HashMap has keys String and values SimpleInitiatedConversation.
Unfortunatelly, the j2s-xmlAdapter-field example available with JAXB 2.0 is more complicated than I need. I just need to store/load HashMap into/from XML and I do not care what it looks like. Is it possible to avoid extending XmlJavaTypeAdaptor for a simple storing a HashMap into XML? Perhaps I use improper annotations in the source code, but I cannot get it working. Any clue?

Answer 1

Ok i figured out one way of doing this by using some classes from JAXP...
SchemaFactory sf = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Schema s = null;
try{
    s = sf.newSchema(new File("Sources/schema/test.xsd"));                    
}catch(Exception e){
    System.err.println("Exception e: " + e.getMessage());
marshaller.setSchema(s);
//MyValidationHandler class implements the ValidationEventHandler interface
MyValidationHandler gv = new MyValidationHandler();
marshaller.setEventHandler(gv);If anyone has something to add let me know!!