<!DOCTYPE hibernate-mapping PUBLIC
   "-//Hibernate/Hibernate Mapping DTD//EN"
   "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="org.my" auto-import="true" default-access="field">
   <class name="Person" discriminator-value="P" mutable="true" dynamic-update="false" dynamic-insert="false" select-before-update="false" lazy="false" abstract="false">
      <id name="id" access="property">
         <column name="id" sql-type="INT8" not-null="true" length="8"/>
         <generator class="native">   
         </generator>
      </id>
      <discriminator type="char" force="false" insert="true">
         <column name="discriminator"/>
      </discriminator>
      <property name="firstname" insert="true" update="true" optimistic-lock="true">
         <column name="firstname" sql-type="VARCHAR(254)" not-null="true" length="254"/>
      </property>
      <property name="lastname" insert="true" update="true" optimistic-lock="true">
         <column name="lastname" sql-type="VARCHAR(254)" not-null="true" length="254"/>
      </property>
      <property name="phone" insert="true" update="true" optimistic-lock="true">
         <column name="phone" sql-type="VARCHAR(254)" length="254"/>
      </property>
      <property name="email" insert="true" update="true" optimistic-lock="true">
         <column name="email" sql-type="VARCHAR(254)" length="254"/>
      </property>
      <property name="discriminator" insert="false" update="false" lazy="false" optimistic-lock="true">
         <column name="discriminator" sql-type="CHAR(1)" length="1"/>
      </property>
      <many-to-one name="Address" cascade="all" access="property" class="org.my.Address" outer-join="false" update="true" insert="true">
         <column name="Add_id" sql-type="INT4" not-null="false" length="4"/>
      </many-to-one>
      <subclass name="Lecturer" discriminator-value="L" dynamic-update="false" dynamic-insert="false" select-before-update="false" lazy="true" abstract="false">
         <property name="officeNumber" insert="true" update="true" optimistic-lock="true">
            <column name="officeNumber" sql-type="VARCHAR(254)" length="254"/>
         </property>
         <property name="consultation" insert="true" update="true" optimistic-lock="true">
            <column name="consultation" sql-type="VARCHAR(254)" length="254"/>
         </property>
         <set name="Course" lazy="true" optimistic-lock="true">
            <key on-delete="noaction" unique="false">
               <column name="Lec_id" sql-type="INT8" not-null="false" length="8"/>
            </key>
            <one-to-many class="Course"/>
         </set>
         <many-to-one name="CourseStudy" access="property" class="org.my.CourseStudy" update="true" insert="true">
            <column name="Cou_id" sql-type="INT4" not-null="false" length="4"/>
         </many-to-one>
         <many-to-one name="LecturerType" access="property" class="org.my.LecturerType" update="true" insert="true">
            <column name="Lec_id" sql-type="INT4" not-null="false" length="4"/>
         </many-to-one>
      </subclass>
      <subclass name="Student" discriminator-value="S" dynamic-update="false" dynamic-insert="false" select-before-update="false" lazy="true" abstract="false">
         <property name="matriculationNumber" insert="true" update="true" optimistic-lock="true">
            <column name="matriculationNumber" sql-type="VARCHAR(254)" length="254"/>
         </property>
         <property name="matriculationDate" insert="true" update="true" optimistic-lock="true">
            <column name="matriculationDate" sql-type="DATE"/>
         </property>
         <set name="CourseAssignment" lazy="true" optimistic-lock="true">
            <key on-delete="noaction" unique="false">
               <column name="Stu_id" sql-type="INT8" not-null="false" length="8"/>
            </key>
            <one-to-many class="org.my.CourseAssignment"/>
         </set>
         <many-to-one name="CourseStudy" access="property" class="org.my.CourseStudy" update="true" insert="true">
            <column name="Cou_id2" sql-type="INT4" not-null="false" length="4"/>
         </many-to-one>
      </subclass>
   </class>
</hibernate-mapping>

      
The List is always empty. As well as I remove the second crit.
Session session = HibernateSessionManager.getSession(true);   
Criteria crit = session.createCriteria(Lecturer.class);
crit.setFetchMode("CourseStudy", FetchMode.JOIN).setFetchMode("Faculty", FetchMode.JOIN);
Criteria cr2 = crit.createCriteria("CourseStudy");
Criteria cr1 = cr2.createCriteria("Faculty");
List list = crit.list();

Session session = HibernateSessionManager.getSession(true);
Criteria crit = session.createCriteria(Student.class);
crit.setFetchMode("CourseStudy", FetchMode.JOIN).setFetchMode("Faculty", FetchMode.JOIN);
Criteria cr2 = crit.createCriteria("CourseStudy");
Criteria cr1 = cr2.createCriteria("Faculty");
List list = crit.list();

if (rest2 != null)
   cr2.add(Restrictions.idEq(crit2.getId()));
if (rest1 != null)
   cr1.add(Restrictions.idEq(crit1.getId()));