I have two entities Student and Address which has one-to-one relation. I have done the mapping without using annotations. The following is the error I got while executing the file::::
Failed to create sessionFactory object.org.hibernate.MappingException: An association from the table student refers to an unmapped class: com.vaannila.student.Address
Exception in thread "main" java.lang.ExceptionInInitializerError
at oomapping.OOMapping.main(OOMapping.java:21)
Caused by: org.hibernate.MappingException: An association from the table student refers to an unmapped class: com.vaannila.student.Address
at org.hibernate.cfg.Configuration.secondPassCompileForeignKeys(Configuration.java:1252)
at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1170)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1286)
at oomapping.OOMapping.main(OOMapping.java:18)
Java Result: 1
BUILD SUCCESSFUL (total time: 1 second)

The following is the code in Student.hbm.xml file::::
<hibernate-mapping>
<class name="oomapping.Student" table="student">
<meta attribute="class-description">This class contains student details.</meta>
<id name="id" type="int" column="student_id">
<generator class="native" />
</id>
<property name="studentName" type="string" not-null="true" length="100" column="student_name" />
<many-to-one name="studentAddress" class="oomapping.Address" column="STUDENT_ADDRESS" not-null="true" cascade="all" unique="true" />
</class>
</hibernate-mapping>


The following is the code in hibernate.cfg.xml file:::::
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.pool_size">10</property>
<property name="current_session_context_class">thread</property>
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<property name="show_sql">true</property>
<property name="hibernate.hbm2ddl.auto">update</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/database1?zeroDateTimeBehavior=convertToNull</property>
<mapping resource="Student.hbm.xml"/>
<mapping resource="Address.hbm.xml"/>
</session-factory>
</hibernate-configuration>

Where do you have Address mapped?? It seems you don´t mapped the other table

The mapping is between
Address.hbm.xml file to address
Student.hbm.xml file to student