hi,
I have 3 tables, TRACK, ARTIST and a table named TRACK_ARTISTS to link to the Track objects for which this Artist is responsible.
I have a class CreateTest which loads artist and track information to the 3 tables.
When I try to load information to the tables I get the below exception
Hibernate 2.1


Full stack trace of any exception that occurs:
[java] Exception in thread "main" net.sf.hibernate.MappingException: An ass
ociation from the table TRACK_ARTISTS refers to an unmapped class: com.oreilly.h
h.Artist
[java] at net.sf.hibernate.cfg.Configuration.secondPassCompileForeignKe
ys(Configuration.java:696)
[java] at net.sf.hibernate.cfg.Configuration.secondPassCompile(Configur
ation.java:680)
[java] at net.sf.hibernate.cfg.Configuration.buildSessionFactory(Config
uration.java:798)
[java] at com.oreilly.hh.CreateTest.main(CreateTest.java:24)
[java] Java Result: 1


Name and version of the database you are using: hsqldb

Track.hbm.xml
Mapping documents:<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>

<class name="com.oreilly.hh.Track" table="TRACK">
<meta attribute="class-description">
Represents a single playable track in the music database.
@author Jim Elliott (with help from Hibernate)
</meta>

<id name="id" type="int" column="TRACK_ID">
<meta attribute="scope-set">protected</meta>
<generator class="native"/>
</id>

<property name="title" type="string">
<meta attribute="use-in-tostring">true</meta>
<column name="TITLE" not-null="true" index="TRACK_TITLE"/>
</property>


<property name="filePath" type="string" not-null="true"/>

<property name="playTime" type="time">
<meta attribute="field-description">Playing time</meta>
</property>

<set name="artists" table="TRACK_ARTISTS">
<key column="TRACK_ID"/>
<many-to-many class="com.oreilly.hh.Artist" column="ARTIST_ID"/>
</set>

<property name="added" type="date">
<meta attribute="field-description">When the track was created</meta>
</property>

<property name="volume" type="short" not-null="true">
<meta attribute="field-description">How loud to play the track</meta>
</property>

</class>

<query name="com.oreilly.hh.tracksNoLongerThan">
<![CDATA[
from com.oreilly.hh.Track as track
where track.playTime <= :length
]]>
</query>

</hibernate-mapping>


Artist.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>

<class name="com.oreilly.hh.Artist" table="ARTIST">
<meta attribute="class-description">
Represents an artist who is associated with a track or album.
@author Jim Elliott (with help from Hibernate)
</meta>

<id name="id" type="int" column="ARTIST_ID">
<meta attribute="scope-set">protected</meta>
<generator class="native"/>
</id>

<property name="name" type="string">
<meta attribute="use-in-tostring">true</meta>
<column name="NAME" not-null="true" unique="true" index="ARTIST_NAME"/>
</property>

<set name="tracks" table="TRACK_ARTISTS" inverse="true">
<meta attribute="field-description">Tracks by this artist</meta>
<key column="ARTIST_ID"/>
<many-to-many class="com.oreilly.hh.Track" column="TRACK_ID"/>
</set>

</class>

<query name="com.oreilly.hh.artistByName">
<![CDATA[
from com.oreilly.hh.Artist as artist
where upper(artist.name) = upper(:name)
]]>
</query>

</hibernate-mapping>


CreateTest.java
package com.oreilly.hh;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.Configuration;

import java.sql.Time;
import java.util.*;

/**
* Create more sample data, letting Hibernate persist it for us.
*/
public class CreateTest {

/**
* Look up an artist record given a name.
* @param name the name of the artist desired.
* @param create controls whether a new record should be created if
* the specified artist is not yet in the database.
* @param session the Hibernate session that can retrieve data
* @return the artist with the specified name, or <code>null</code> if no
* such artist exists and <code>create</code> is <code>false</code>.
* @throws HibernateException if there is a problem.
*/
public static Artist getArtist(String name, boolean create,
Session session)
throws HibernateException
{
Query query = session.getNamedQuery(
"com.oreilly.hh.artistByName");
query.setString("name", name);
Artist found = (Artist)query.uniqueResult();
if (found == null && create) {
found = new Artist(name, new HashSet());
session.save(found);
}
return found;
}

/**
* Utility method to associate an artist with a track
*/
private static void addTrackArtist(Track track, Artist artist) {
track.getArtists().add(artist);
}

public static void main(String args[]) throws Exception {
// Create a configuration based on the properties file we've put
// in the standard place.
Configuration config = new Configuration();

// Tell it about the classes we want mapped, taking advantage of
// the way we've named their mapping documents.
config.addClass(Track.class).addClass(Artist.class);

// Get the session factory we can use for persistence
SessionFactory sessionFactory = config.buildSessionFactory();

// Ask for a session using the JDBC information we've configured
Session session = sessionFactory.openSession();
Transaction tx = null;
try {
// Create some data and persist it
tx = session.beginTransaction();

Track track = new Track("Russian Trance",
"vol2/album610/track02.mp3",
Time.valueOf("00:03:30"), new Date(),
(short)0, new HashSet(), new HashSet());
addTrackArtist(track, getArtist("PPK", true, session));
session.save(track);

track = new Track("Video Killed the Radio Star",
"vol2/album611/track12.mp3",
Time.valueOf("00:03:49"), new Date(),
(short)0, new HashSet(), new HashSet());
addTrackArtist(track, getArtist("The Buggles", true, session));
session.save(track);


track = new Track("Gravity's Angel",
"vol2/album175/track03.mp3",
Time.valueOf("00:06:06"), new Date(),
(short)0, new HashSet(), new HashSet());
addTrackArtist(track, getArtist("Laurie Anderson", true, session));
session.save(track);

track = new Track("Adagio for Strings (Ferry Corsten Remix)",
"vol2/album972/track01.mp3",
Time.valueOf("00:06:35"), new Date(),
(short)0, new HashSet(), new HashSet());
addTrackArtist(track, getArtist("William Orbit", true, session));
addTrackArtist(track, getArtist("Ferry Corsten", true, session));
addTrackArtist(track, getArtist("Samuel Barber", true, session));
session.save(track);

track = new Track("Adagio for Strings (ATB Remix)",
"vol2/album972/track02.mp3",
Time.valueOf("00:07:39"), new Date(),
(short)0, new HashSet(), new HashSet());
addTrackArtist(track, getArtist("William Orbit", true, session));
addTrackArtist(track, getArtist("ATB", true, session));
addTrackArtist(track, getArtist("Samuel Barber", true, session));
session.save(track);

track = new Track("The World '99",
"vol2/singles/pvw99.mp3",
Time.valueOf("00:07:05"), new Date(),
(short)0, new HashSet(), new HashSet());
addTrackArtist(track, getArtist("Pulp Victim", true, session));
addTrackArtist(track, getArtist("Ferry Corsten", true, session));
session.save(track);

track = new Track("Test Tone 1",
"vol2/singles/test01.mp3",
Time.valueOf("00:00:10"), new Date(),
(short)0, new HashSet(), new HashSet());
track.getComments().add("Pink noise to test equalization");
session.save(track);

// We're done; make our changes permanent
tx.commit();

} catch (Exception e) {
if (tx != null) {
// Something went wrong; discard all partial changes
tx.rollback();
}
throw e;
} finally {
// No matter what, close the session
session.close();
}

// Clean up after ourselves
sessionFactory.close();
}
}


Appreciate all help.
thanks in advance