if (_lob instanceof Clob) {
if (_lob instanceof Blob) { Blob blob = (Blob) _lob; blob.truncate(length); } else if (_lob instanceof Clob) {
  public boolean truncate(Env env,                          @Optional("0") int length)  {    try {      switch (_type) {      case OracleModule.OCI_D_FILE:        break;      case OracleModule.OCI_D_LOB:        if (_lob instanceof Clob) {          Clob clob = (Clob) _lob;          clob.truncate(length);        }        break;      case OracleModule.OCI_D_ROWID:        break;      }      return true;    } catch (Exception ex) {      log.log(Level.FINE, ex.toString(), ex);      return false;    }  }