I am using Hibernate Many-to-Many association using the hibernate_reference.pdf found at hibernate site. I

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Asked: June 9, 20262026-06-09T05:09:08+00:00 2026-06-09T05:09:08+00:00

I am using Hibernate Many-to-Many association using the hibernate_reference.pdf found at hibernate site. I

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I am using Hibernate Many-to-Many association using the hibernate_reference.pdf found at hibernate site. I am using same entities Event.java and Person.java as described in the document.

I have seen many facing “could not initialize a collection exception” and many addressed the issue but none of the solution mentioned in the stack over flow posts fixed my issue. May be those solution do not work for Many-to-Many association or I am having some issue with my configuration. Following are my hbm.xml files:

Event.hbm.xml:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="roseindia.tutorial.hibernate">
    <class name="Event" table="EVENTS">

        <id name="id" column="EVENT_ID">
            <generator class="native" />
        </id>

        <property name="date" type="timestamp" column="EVENT_DATE" />
        <property name="title" type="string" />
        <property name="location" type="string" column="LOC" />

        <set name="participants" table="PERSON_EVENT" inverse="true" lazy="false" cascade="all" >
            <key column="EVENT_ID" not-null="true" />
            <many-to-many column="PERSON_ID" class="Person" />
        </set>
    </class>
</hibernate-mapping>

Event.java

public class Event implements java.io.Serializable {
    private long id;
    private String title;
    private Date date;
    private String location;

    public Event() {
        //participants = new HashSet<Person>(0);
    }

    private Set participants = new HashSet(0);

    public Set getParticipants() {
        return participants;
    }

    public void setParticipants(Set participants) {
        this.participants = participants;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((date == null) ? 0 : date.hashCode());
        //result = prime * result + (int) (id ^ (id >>> 32));
        result = prime * result
                + ((location == null) ? 0 : location.hashCode());
        //result = prime * result + ((participants == null) ? 0 : participants.hashCode());
        result = prime * result + ((title == null) ? 0 : title.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Event other = (Event) obj;
        if (date == null) {
            if (other.date != null)
                return false;
        } else if (!date.equals(other.date))
            return false;

        if (location == null) {
            if (other.location != null)
                return false;
        } else if (!location.equals(other.location))
            return false;

        if (title == null) {
            if (other.title != null)
                return false;
        } else if (!title.equals(other.title))
            return false;
        return true;
    }

    @SuppressWarnings("unchecked")
    public void addToParticipants(Person person) {
        this.getParticipants().add(person);
        //person.addToEvent(this);
        person.getEvents().add(this);
    }

    public void removeFromParticipants(Person person) {
        this.getParticipants().remove(this);
        person.getEvents().remove(person);
    }

    public long getId() {
        return id;
    }

    private void setId(long id) {
        this.id = id;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getLocation() {
        return this.location;
    }

    public void setLocation(String location) {
        this.location = location;
    }
}

Person.hbm.xml:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="roseindia.tutorial.hibernate">
    <class name="Person" table="PERSON">
        <id name="id" column="PERSON_ID">
            <generator class="native" />
        </id>
        <property name="age" />
        <property name="firstname" />
        <property name="lastname" />

        <set name="events" table="PERSON_EVENT" inverse="false" lazy="true" cascade="all" >
            <key column="PERSON_ID" not-null="true" />
            <many-to-many column="EVENT_ID" class="Event" />
        </set>

        <set name="emailAddresses" table="PERSON_EMAIL_ADDR">
            <key column="PERSON_ID" />
            <element type="string" column="EMAIL_ADDR" />
        </set>
    </class>
</hibernate-mapping>

Person.java

import java.util.HashSet;
import java.util.Set;

public class Person implements java.io.Serializable {
    private Set events = new HashSet<Event>();
    private Set emailAddresses = new HashSet();

    public Set getEmailAddresses() {
        return emailAddresses;
    }

    public void setEmailAddresses(Set emailAddresses) {
        this.emailAddresses = emailAddresses;
    }

    public void addToEvent(Event event) {
        this.getEvents().add(event);
        //event.addToParticipants(this);
        event.getParticipants().add(this);
    }

    public void removeFromEvent(Event event) {
        this.getEvents().remove(event);
        //event.removeFromParticipants(this);
        event.getParticipants().remove(this);
    }

    public Set getEvents() {
        return events;
    }

    public void setEvents(Set events) {
        this.events = events;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public int getAge() {
        return age;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + age;
        result = prime * result
                + ((firstname == null) ? 0 : firstname.hashCode());
        result = prime * result
                + ((lastname == null) ? 0 : lastname.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Person other = (Person) obj;
        if (age != other.age)
            return false;

        if (firstname == null) {
            if (other.firstname != null)
                return false;
        } else if (!firstname.equals(other.firstname))
            return false;

        if (lastname == null) {
            if (other.lastname != null)
                return false;
        } else if (!lastname.equals(other.lastname))
            return false;
        return true;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getFirstname() {
        return firstname;
    }

    public void setFirstname(String firstname) {
        this.firstname = firstname;
    }

    public String getLastname() {
        return lastname;
    }

    public void setLastname(String lastname) {
        this.lastname = lastname;
    }

    private Long id;
    private int age;
    private String firstname;
    private String lastname;

    public Person() {
    }
}

ManyToManyExample.java

public class ManyToManyExample {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Session session = null;
        try {
            SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
            session = sessionFactory.openSession();
            Transaction tx1 = session.beginTransaction();

            System.out.println("Loading Record");
            Event theEvent = (Event) session.get(Event.class, new Long(1));
            session.refresh(theEvent);
            Person person = new Person();
            person.setAge(31);
            person.getEvents().add(theEvent);
            person.setFirstname("RRRRRR");
            person.setLastname("NNNNNN");
            person.getEmailAddresses().add("RRRRRR@yahoo.com");

            theEvent.getParticipants().add(person); // Adding person ref. to event for many to many relation

            session.save(theEvent);
            session.save(person);
            tx1.commit(); 

            System.out.println("Done...");

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            session.flush();
            session.close();
        }
    }
}

I get following error when I run above sample:
INFO DefaultLoadEventListener:129 – Error performing load command
org.hibernate.exception.GenericJDBCException: could not initialize a collection: [roseindia.tutorial.hibernate.Event.participants#1]
at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:82)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:70)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.loader.Loader.loadCollection(Loader.java:1351)
at org.hibernate.loader.collection.CollectionLoader.initialize(CollectionLoader.java:101)
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:484)
at org.hibernate.event.def.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:60)
at org.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:1346)
at org.hibernate.collection.AbstractPersistentCollection.forceInitialization(AbstractPersistentCollection.java:269)
at org.hibernate.engine.PersistenceContext.initializeNonLazyCollections(PersistenceContext.java:745)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:208)
at org.hibernate.loader.Loader.loadEntity(Loader.java:1255)
at org.hibernate.loader.entity.EntityLoader.load(EntityLoader.java:139)
at org.hibernate.loader.entity.EntityLoader.load(EntityLoader.java:124)
at org.hibernate.persister.entity.BasicEntityPersister.load(BasicEntityPersister.java:2453)
at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:387)
at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:368)
at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:166)
at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:140)
at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:249)
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:123)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:561)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:556)
at roseindia.tutorial.hibernate.ManyToManyExample.main(ManyToManyExample.java:24)
Caused by: java.sql.SQLException: [Microsoft][ODBC SQL Server Driver]Invalid Descriptor Index
at sun.jdbc.odbc.JdbcOdbc.createSQLException(JdbcOdbc.java:6956)
at sun.jdbc.odbc.JdbcOdbc.standardError(JdbcOdbc.java:7113)
at sun.jdbc.odbc.JdbcOdbc.SQLGetDataDouble(JdbcOdbc.java:3656)
at sun.jdbc.odbc.JdbcOdbcResultSet.getDataDouble(JdbcOdbcResultSet.java:5574)
at sun.jdbc.odbc.JdbcOdbcResultSet.getLong(JdbcOdbcResultSet.java:632)
at sun.jdbc.odbc.JdbcOdbcResultSet.getLong(JdbcOdbcResultSet.java:650)
at org.hibernate.type.LongType.get(LongType.java:26)
at org.hibernate.type.NullableType.nullSafeGet(NullableType.java:77)
at org.hibernate.type.NullableType.nullSafeGet(NullableType.java:68)
at org.hibernate.persister.collection.AbstractCollectionPersister.readKey(AbstractCollectionPersister.java:612)
at org.hibernate.loader.Loader.readCollectionElement(Loader.java:545)
at org.hibernate.loader.Loader.readCollectionElements(Loader.java:344)
at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:299)
at org.hibernate.loader.Loader.doQuery(Loader.java:384)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:203)
at org.hibernate.loader.Loader.loadCollection(Loader.java:1344)
… 20 more

I create person object and add event to by fetching event using session.get(…). For many-to-many relation, after adding every object to person’s event list, i am doing otherway around and adding person to participants list in event object and that throws exception. Any helpful or guidance is deeply appreciated!

I am using SQL Server 2008 as database.

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1 Answer

Editorial Team · Answer 1 · 2026-06-09T05:09:09+00:00

Editorial Team

2026-06-09T05:09:09+00:00Added an answer on June 9, 2026 at 5:09 am

try to change jdbc driver package , you can use jtds-1.2.jar ,and set driver class to net.sourceforge.jtds.jdbc.Driver

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