<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/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.url">jdbc:mysql://localhost:3306/itaprojekat?zeroDateTimeBehavior=convertToNull</property>
    <property name="hibernate.connection.username">root</property>
    <property name="hibernate.connection.password">2007991710126</property>
    <property name="hibernate.connection.autocommit">true</property>
    <property name="hibernate.show_sql">true</property>
    <property name="hibernate.hbm2ddl.auto">update</property>
    <mapping class="itaprojekat.Kategorija"></mapping>
  </session-factory>
</hibernate-configuration>

public class HibernateUtil {
    private static Session sesija = null;
    public static Session getSession(){
        if(sesija==null){
            Configuration cfg = new Configuration();
            cfg.configure("/config/hibernate.cfg.xml");
            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(cfg.getProperties()).build();
            SessionFactory sessionFactory = cfg.buildSessionFactory(serviceRegistry);
            sesija = sessionFactory.openSession();
        }
        return sesija;
    }
}

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
        Session sesija = HibernateUtil.getSession();
        sesija.beginTransaction();
        InputContext ic = tfNaziv.getInputContext(); //tfNaziv is my textfield
        Kategorija k = new Kategorija();
        k.setNaziv(ic);
        sesija.save(k);
        sesija.getTransaction().commit();

    }