I have problem with locking some record from ORACLE 9i DB.

I create Entity Bean, Session Bean in JDeveloper 11g.
My Persistant_Unit is:

<persistence-unit name="HibernatePU">
 <provider>org.hibernate.ejb.HibernatePersistence</provider>
 <properties>
 <property name="hibernate.archive.autodetection" value="class, hbm"/>
 <property name="hibernate.connection.driver_class" value="oracle.jdbc.driver.OracleDriver"/>
 <property name="hibernate.connection.url" value="jdbc:oracle:thin:@localhost:1521:XE"/>
 <property name="hibernate.connection.username" value="zoran"/>
 <property name="hibernate.connection.password" value="zoran"/>
 <!-- <property name="hibernate.show_sql" value="false"/> -->
 <property name="hibernate.dialect" value="org.hibernate.dialect.OracleDialect"/>
 <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
 </properties>
</persistence-unit>

In Java class I wrote:

private EntityManagerFactory EntityManagerFactoryM = Persistence.createEntityManagerFactory("HibernatePU");

private EntityManager EntityManagerMesto;

EntityManagerMesto = EntityManagerFactoryM.createEntityManager();


 private void Transaction()
 {
 Mesto mestoTB = EntityManagerMesto.find(Mesto.class,1);

 EntityTransaction transactionM = EntityManagerMesto.getTransaction();

 transactionM.begin();

 EntityManagerMesto.lock(mestoTB, LockModeType.WRITE);

 System.out.println("testEJB: " + mestoTB.getNaziv());
 }


 Private void ExitForm()
 {
 transactionM.rollback();
 }

I want to know if this is right code to LOCK one recored from ORACLE 9I and not to allow to anybody to change that row until I call function
ExitForm() --- transactionM.rollback()