Hibernate3:Unknown entity: java.lang.String

  public void deleteAllObjects(String className) throws Exception{
    // Ask for a session using the JDBC information we've configured
    Session session = sessionFactory.openSession();
    Transaction tx = null;
    try {
      tx = session.beginTransaction();
      session.delete("from " +className);
      // We're done; make our changes permanent
      tx.commit();

    }catch (Exception e) {
      if (tx != null) {
        // Something went wrong; discard all partial changes
        tx.rollback();
      }
      throw e;
    } finally {
      // No matter what, close the session
      session.close();
    }
  }

String hqlDelete = "delete NativeTester";
int deletedEntities = session.createQuery( hqlDelete )
.executeUpdate();