Hi.
I have some errors while validating my form.

struts.xml

<package name="view" extends="struts-portlet-default" namespace="/view">

 <action name="AddClientRequestAction_*" method="{1}" class="autopay.portlet.action.AddClientRequestAction">
 <result name="input">/WEB-INF/jsp/view/addRequest.jsp</result>
 <result name="source">/WEB-INF/jsp/view/addRequest.jsp</result>
 <result>/WEB-INF/jsp/view/ok.jsp</result>
 </action>
 </package>

AddClientRequestAction

public class AddClientRequestAction extends ActionSupport {
 private String a = "aaaaaaaaaaaaa";

 @Override
 public String execute() throws Exception {
 System.out.println("a: " + a);


 if (isInvalid(a)) return INPUT;
 addActionMessage("my action message");
 return SUCCESS;
 }

 public String getA() {
 return a;
 }

 public void setA(String a) {
 this.a = a;
 }

 public void validate() {
 System.out.println("AddClientRequestAction - VALIDATE!!!");
 super.validate();
 }

 private boolean isInvalid(String value) {
 return (value == null || value.length() == 0);
 }
}

Exception

2008-10-27 18:56:52,452 ERROR [org.jboss.portal.core.model.portal.control.page.DefaultPageControlPolicy] Rendering portlet window produced an error
javax.portlet.PortletException: Error executing action renderDirect....

Caused by: javax.portlet.PortletException: org.apache.jasper.JasperException: java.lang.NullPointerException
at org.jboss.portal.portlet.impl.jsr168.api.PortletRequestDispatcherImpl.include(PortletRequestDispatcherImpl.java:91)
...
interesting part

Caused by: java.lang.NullPointerException
at java.text.MessageFormat.applyPattern(MessageFormat.java:422)
at java.text.MessageFormat.(MessageFormat.java:350)
at com.opensymphony.xwork2.DefaultTextProvider.getText(DefaultTextProvider.java:70)
at com.opensymphony.xwork2.DefaultTextProvider.getText(DefaultTextProvider.java:111)
at org.apache.struts2.util.TextProviderHelper.getText(TextProviderHelper.java:62)
at org.apache.struts2.util.TextProviderHelper.getText(TextProviderHelper.java:105)
at org.apache.struts2.components.UIBean.evaluateParams(UIBean.java:631)
at org.apache.struts2.components.UIBean.end(UIBean.java:509)
at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)
at org.apache.jsp.WEB_002dINF.jsp.view.addRequest_jsp._jspx_meth_s_005ftextfield_005f0(addRequest_jsp.java:200)
at org.apache.jsp.WEB_002dINF.jsp.view.addRequest_jsp._jspx_meth_s_005fform_005f0(addRequest_jsp.java:132)
at org.apache.jsp.WEB_002dINF.jsp.view.addRequest_jsp._jspService(addRequest_jsp.java:73)

Extract from line 422 of MessageFormat.java as it is in Java 1.6.0_07:

for (int i = 0; i < pattern.length(); ++i) {

It seems that, struts 2 validator can't find message patterns. But i tried a great numbers of message mapping, and with out localized messages only addErrorMessage("error") method.

Could anyone help me with this error?
Thanks.