java.lang.UnsupportedOperationException

[sonia pandit]

   

package hud.gov.service;

import java.util.List;
import java.util.ArrayList;

public class ViewFile {
  private List<String> filesList ;
   
public List<String> getFilesList(){
   filesList = new ArrayList<String>();
   filesList.add("test1.xls");
   filesList.add("test2.xls");
   filesList.add("test3.xmls");
   return filesList;
	
} 

Here is the stackTrace:

    java.lang.UnsupportedOperationException
	at javax.faces.context.ExternalContext.setResponse(ExternalContext.java:149)
	at org.apache.myfaces.application.jsp.JspViewHandlerImpl.buildView(JspViewHandlerImpl.java:483)
	at org.apache.myfaces.application.jsp.JspViewHandlerImpl.renderView(JspViewHandlerImpl.java:337)
	at org.apache.myfaces.trinidadinternal.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:182)
	at org.apache.myfaces.lifecycle.RenderResponseExecutor.execute(RenderResponseExecutor.java:41)
	at org.apache.myfaces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:140)
	at javax.faces.webapp.FacesServlet.service(FacesServlet.java:155)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
	at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
	at java.lang.Thread.run(Unknown Source)

What is the problem with this code? It throws a java.lang.UnsupportedOperationException

THanks,

SOnia