title: Coding JSF, commandButton's navigation-action-outcome by Code
body: <p>i try to fix unmanagable code like this:</p>
  
  <pre><code>&lt;a4j:commandButton action="dia_ok" actionListener="#{...}" ajaxSingle="true" .../&gt;
  </code></pre>
  
  <p>i fix it by bind the button to an ManagedBean and swap all the attributes to Java-Code, so ill only have:</p>
  
  <pre><code>&lt;a4j:commandButton binding="#{...}"/&gt;
  </code></pre>
  
  <p>I successfully coded setAjaxSingle(true) and the actionListener-attribute, but i fail on code the action-Attribute.</p>
  
  <p>My question is: how can i specify the action-outcome whereat the method button.setActionExpression() does only allows argument of MethodExpression instead of String?</p>