I am getting a NullPointerException in an action form that should
theoretically not be possible :(
Any ideas/help/suggestions are appreciated. Obviously it "is possible"
:).
I happens when I'm testing. I find a problem, leave my browser up, then
stop/start Tomcat. I select a "home page" link from the page that is
still displayed - its simply an action wrapped simple JSP page with no
dynamic data that serves as a central bulletin board for my users.
After that is displayed, I go back to the page that I am developing on.
Boom! I get the NPE in the middle of a getter method on the action form.
Here is the method - the NPE is flagged at the line "if
(log.isDebugEnabled()) {".
...
public String getMeasParmsId() {
if (log.isDebugEnabled()) {
log.debug("getMeasParmsId()=" + measParmsId);
}
return measParmsId;
}
...
The "log" variable is initialized when the Action form is instantiated,
like so:
public class ChartWizardForm extends ActionForm implements
java.io.Serializable {
private transient Log log =
LogFactory.getLog(ChartWizardForm.class);
...
Obviously I'm missing something pretty basic. Is Tomcat re-using a form
instance across restarts? I've got pretty much default settings in
Tomcat:
Here is the exception stack trace:
2004-07-10 12:21:00 StandardWrapperValve[action]: Servlet.service() for
servlet action threw exception
java.lang.NullPointerException
at
com.ltoj.webapp.form.ChartWizardForm.getMeasParmsId(ChartWizardForm.java
:137)
at
com.ltoj.webapp.action.AdminChartWizardAction.stepMeasParms(AdminChartWi
zardAction.java:88)
at
com.ltoj.webapp.action.AdminChartWizardAction.unspecified(AdminChartWiza
rdAction.java:66)
at
org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.j
ava:260)
at
com.ltoj.webapp.action.BaseAction.execute(BaseAction.java:162)
at
org.apache.struts.action.RequestProcessor.processActionPerform(RequestPr
ocessor.java:484)
at
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:
274)
at
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
at
org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:507)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:743)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Applica
tionFilterChain.java:284)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilt
erChain.java:204)
at
com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingF
ilter.java:132)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Applica
tionFilterChain.java:233)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilt
erChain.java:204)
at
com.ltoj.webapp.filter.BreadCrumbFilter.doFilter(BreadCrumbFilter.java:9
4)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Applica
tionFilterChain.java:233)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilt
erChain.java:204)
at
com.ltoj.webapp.filter.ActionFilter.doFilter(ActionFilter.java:372)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Applica
tionFilterChain.java:233)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilt
erChain.java:204)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValv
e.java:257)
at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveCo
ntext.java:151)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:5
67)
at
org.apache.catalina.core.StandardContextValve.invokeInternal(StandardCon
textValve.java:245)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValv
e.java:199)
at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveCo
ntext.java:151)
at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(Authenticator
Base.java:587)
at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveCo
ntext.java:149)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:5
67)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java
:184)
at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveCo
ntext.java:151)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java
:164)
at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveCo
ntext.java:149)
at
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:578
)
at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveCo
ntext.java:149)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:5
67)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.
java:156)
at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveCo
ntext.java:151)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:5
67)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:972)
at
org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:206)
at
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:83
3)
at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processC
onnection(Http11Protocol.java:732)
at
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:61
9)
at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool
.java:688)
at java.lang.Thread.run(Thread.java:536)
Thanks - Richard
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