terminalError NullPointerException

General
1

Occasionally users of my app are reporting that they get and ! with exception and the logs are showing the below terminalError and stack trace and I have no idea what it is referring to. I am using ICEpush addon in my app to push changes to the users. Could this be an ICEpush addon bug? How do I go about debugging this?

Thanks, Tom

Oct 25, 2011 12:13:54 PM com.vaadin.Application terminalError
SEVERE: Terminal error:
com.vaadin.event.ListenerMethod$MethodException
Cause: java.lang.NullPointerException
at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:510)
at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:164)
at com.vaadin.ui.AbstractComponent.fireEvent(AbstractComponent.java:1193)
at com.vaadin.ui.Button.changeVariables(Button.java:198)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariableBurst(AbstractCommunicationManager.java:1297)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariables(AbstractCommunicationManager.java:1217)
at com.vaadin.terminal.gwt.server.CommunicationManager.handleUidlRequest(CommunicationManager.java:296)
at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(AbstractApplicationServlet.java:501)
at org.vaadin.artur.icepush.ICEPushServlet.service(ICEPushServlet.java:72)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:534)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:475)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:119)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:516)
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:226)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:929)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:403)
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:184)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:864)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:117)
at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:247)
at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:151)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:114)
at org.eclipse.jetty.server.Server.handle(Server.java:352)
at org.eclipse.jetty.server.HttpConnection.handleRequest(HttpConnection.java:596)
at org.eclipse.jetty.server.HttpConnection$RequestHandler.content(HttpConnection.java:1068)
at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:805)
at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:218)
at org.eclipse.jetty.server.HttpConnection.handle(HttpConnection.java:426)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:508)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint.access$000(SelectChannelEndPoint.java:34)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:40)
at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:451)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException

2

Looks like the NullPointerException occurs in some ClickListener for a Button in your application. The log does not say which button, but probably the one for the button which the user clicked.

The error is probably not caused by ICEPush, but I suppose anything is always possible.

3

Hi Marko,
Thanks for your response. Our application only has one button and that isn’t pressed very often. Is it definitely a button or could it be a input field with a change listener?

Thanks, Tom

4

It is a Button or a subclass of Button (NativeButton or CheckBox).

5

Hi Team,
I’m always getting the below error while running timer job. Please, any one can help with this.

com.vaadin.Application.terminalError Terminal error:
com.vaadin.event.ListenerMethod$MethodException: Invocation of method buttonClick in org.activiti.explorer.ui.mainlayout.MainMenuBar$ShowManagementClickListener failed.
at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:530)
at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:164)
at com.vaadin.ui.AbstractComponent.fireEvent(AbstractComponent.java:1219)
at com.vaadin.ui.Button.fireClick(Button.java:567)
at com.vaadin.ui.Button.changeVariables(Button.java:223)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.changeVariables(AbstractCommunicationManager.java:1460)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariableBurst(AbstractCommunicationManager.java:1404)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariables(AbstractCommunicationManager.java:1329)

Thanks,
Ajay

6

I would start by debugging your application code, e.g. by setting break point somewhere in your ShowManagementClickListener.