I have a problem with LazyInitializationException and I don’t know how to fix it. I get the following exception:

Exception in thread “main” org.hibernate.LazyInitializationException: could not initialize proxy – no Session
at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:167)
at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:215)
at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:190)
at sei.persistence.wf.entities.Element_$$_jvstc68_47.getNote(Element_$$_jvstc68_47.java)
at JSON_to_XML.createBpmnRepresantation(JSON_to_XML.java:139)
at JSON_to_XML.main(JSON_to_XML.java:84)

when I try to call from main the following lines:
Model subProcessModel = getModelByModelGroup(1112);
System.out.println(subProcessModel.getElement().getNote());

I implemented the getModelByModelGroup(int modelgroupid) method firstly like this :

public static Model getModelByModelGroup(int modelGroupId, boolean openTransaction) {

Session session = SessionFactoryHelper.getSessionFactory().getCurrentSession();
Transaction tx = null;

if (openTransaction) {
tx = session.getTransaction();
}

String responseMessage = "";

try {
if (openTransaction) {
tx.begin();
}
Query query = session.createQuery("from Model where modelGroup.id = :modelGroupId");
query.setParameter("modelGroupId", modelGroupId);

List modelList = (List)query.list();
Model model = null;

for (Model m : modelList) {
if (m.getModelType().getId() == 3) {
model = m;
break;
}
}

if (model == null) {
Object[] arrModels = modelList.toArray();
if (arrModels.length == 0) {
throw new Exception("Non esiste ");
}

model = (Model)arrModels[0];
}

if (openTransaction) {
tx.commit();
}

return model;

} catch(Exception ex) {
if (openTransaction) {
tx.rollback();
}
ex.printStackTrace();
if (responseMessage.compareTo("") == 0) {
responseMessage = "Error" + ex.getMessage();
}
return null;
}
}

Anybody here to help me with this problem, please?