Sorting a jsf datatable

[guess85]

Hi everyobody, I have this jsf datatable

<h:dataTable value="#{studentBean.lista_studenti}" var="lista">
<h:column>
<f:facet name="header">
<hutputText value="Cognome" />
</f:facet>
<hutputText value="#{lista.cognome}"/>
</h:column>
<h:column>
<f:facet name="header">
<hutputText value="Nome" />
</f:facet>
<hutputText value="#{lista.nome}"/>
</h:column>
<h:column>
<f:facet name="header">
<hutputText value="Matricola" />
</f:facet>
<hutputText value="#{lista.matricola}"/>
</h:column>
</h:dataTable>

and i wish to sort it by the parameter "Cognome" without sorting the
list in the bean. What can I do? Thanks to all.