Servlets: java.lang.IllegalStateException with response.sendRedirect()

Topic:  Servlets 2.4

Application Server: JBoss 4.0.2 / Tomcat 5.5.9

Exception:

ERROR [[abcde]] Servlet.service() for servlet hello threw exception

java.lang.IllegalStateException
        at org.apache.catalina.connector.ResponseFacade.sendRedirect(ResponseFac
ade.java:423)
        at com.HelloWorldServlet.doGet(HelloWorldServlet.java:33)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:252)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:173)
        at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFi
lter.java:81)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:202)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:173)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:213)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:178)
        at org.jboss.web.tomcat.security.CustomPrincipalValve.invoke(CustomPrinc
ipalValve.java:39)
        at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(Securit
yAssociationValve.java:153)
        at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValv
e.java:59)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j
ava:126)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
ava:105)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
ve.java:107)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.jav
a:148)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java
:856)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.proce
ssConnection(Http11Protocol.java:744)
        at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpo
int.java:527)
        at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWor
kerThread.java:112)
        at java.lang.Thread.run(Thread.java:619)

Resolution:

The java.lang.IllegalStateException exception thrown in the context of the response.sendRedirect() method indicates that the output response had already been committed after which the sendRedirect() method was invoked, i.e., after the out.close() statement

The solution is to either to put sendRedirect() before out.close() or better still, if a redirection is what was desired in any case, the user will not see any response that was sent, therefore to remove all statements that write to the Servlet output response.