How can I refresh entities in the following case.

I have a page that contains:

<div class="entry">
 <a4j:log hotkey="M" />
 <a4j:commandButton value="Reload" reRender="Sensor"/>
 <div class="label">Sensor:</div>
 <div class="input">
 <a4j:region renderRegionOnly="false">
 <h:selectOneMenu id="Sensor" value="#{messkette.sensor}"
 converter="#{selectItemHelfer}" required="true" disabled="#{gesperrt}">
 <f:selectItems value="#{messketteEditor.alleSensorenMitBlank}" />
 <a4j:support event="onchange" reRender="Funktion, Sensormessbereich, Einheit, Sensorwarnung" />
 </h:selectOneMenu>
 </a4j:region>
 <h:message for="Sensor" styleClass="message" />
 <div><h:outputText id="Sensorwarnung" value="#{messketteEditor.sensorWarnung}" styleClass="kursiv" /></div>
 </div>
 </div

Sometimes I need to edit or create a entry from database in a second instance of web browser. So the list in messketteEditor has changed. But when I perform the Reload commandButton the outcome is the same with no changes.
What I have to do tell the Entitymanger to refresh the list from database.

Here the function that will be executet when a entity is changed or created

public String speichern() {

 checkKorrekterAufruf();

 if (!vorSpeichern()) {
 ejbCtx.setRollbackOnly();
 return null;
 }

 try {

 String message = "";

 T entity = getEntity();

 if (neu) {
 //Neues Entity, anlegen
 em.persist(entity);
 message = angelegtMessage();
 loggeAenderung(getEntity(), "angelegt");
 } else {
 //Bestehendes Entity, Änderungen übernehmen
 setEntity(em.merge(entity));
 message = bearbeitetMessage();
 loggeAenderung(getEntity(), "bearbeitet");
 }

 nachSpeichern();System.out.println(entity);

 em.flush();

 addMessage(message);

 } catch (Exception ex) {
 ejbCtx.setRollbackOnly();
 addWarning(speichernError() + " " + exceptionListe(ex));
 System.out.println(ex.getMessage());
 ex.printStackTrace();

 return null;
 }

 return zurueckOutcome;
 }

and this is the code to return the list

private List<StandardEntity> listeHolen(Class<? extends StandardEntity> klasse, String where, String order) {

 String klassenName = klasse.getName();

 String query = "from " + klassenName;
 if (where != null)
 query += " where " + where;
 if (order != null)
 query += " order by " + order;

 List<StandardEntity> liste;

 try {
 liste = (List<StandardEntity>) em.createQuery(query).getResultList();
 } catch (Exception ex) {
 //Im Fehlerfall (z.B. nichts gefunden) leere Liste erzeugen
 ex.printStackTrace();
 liste = new Vector<StandardEntity>();
 }

 return liste;
 }

Is there a solution for this case?


Thanks
andi