<result type="redirect-action">
  <param name="actionName">NextAction</param>
  <param name="parse">true</param>
  <param name="redirectMessage">${redirectMessage}</param>
</result>

http://www.vitarara.org/cms/struts_2_cookbook/post_and_redirect

Set parse attribute to true for the redirect-action result.

Add a redirect message when doing Post then Redirect in Struts2

Java