Person.hbm.xml
---------------------------

<class name="Person">
<id name="id" column="personId">
<generator class=“identity"/>
</id>

<one-to-one name="address"/>

<property name="name" type="string">
<column name="Name"/>
</property>

</class>

address.hbm.xml
------------------------------------
<class name="Address">

<id name="id" column="personId">
<generator class="foreign">
<param name="property">person</param>
</generator>
</id>

<one-to-one name="person" constrained="true"/>

<property name="state" type="string">
<column name="STATE"/>
</property>

</class>



Person.java
-----------------

class Person
{
int id;
String name;
Address address;

setter/getter for id, name and address;

}



Address.java
-----------------
class Address
{

int id;
Person person;
String state;

setter/getter for id, state and person;

}

Client.java
--------------------

class Client
{

SessionFactory sessionFactory = new Configuration().configure ().buildSessionFactory ();
Session session = sessionFactory.openSession ();
Transaction tx = session.beginTransaction();

tx.begin();

Person person = new Person();
person.setName("Test");

Address address = new Address();
address.setState(NY);

person.setAddress(address);

session.save(person); // ********** SHOULD SAVE ADDRESS ALSO

tx.commit();
}

<one-to-one name="address" cascade="all"/>

<id name="id" column="ADDRESS_ID">
   <generator class="foreign">
   <param name="property">person</param>
   </generator>
</id>
<one-to-one name="person" constrained="true"/>

person = new Person();
address ad = new Address();
ad.setPerson(person);
person.setAddress(ad);
session.save(person);