How to trace/debug?

[Steve Horne <st...@gmail.com>]

I am using MyFaces, Trinidad and Facelets.  I am a fairly experienced JSF
developer, but I quite often have errors that I can't get additional
information about, and I wind up having to debug by removing things and
putting them back in trying to localize a problem.  I seem to quite often
have a null pointer exception during rendering that doesn't give me any real
info about where the problem is.

How are you debugging your JSF app?  Any suggestion would be welcome.

For example, when trying to hit a page in my app, I get the following stack
trace:

10:56:12,148 INFO  [STDOUT] 10:56:12,148 ERROR [[faces]] Servlet.service()
for servlet faces threw exception
java.lang.NullPointerException
    at
org.apache.myfaces.trinidadinternal.renderkit.core.xhtml.FormRenderer.encodeEnd
(FormRenderer.java:206)
    at org.apache.myfaces.trinidad.render.CoreRenderer.encodeEnd(
CoreRenderer.java:224)
    at org.apache.myfaces.trinidad.component.UIXComponentBase.encodeEnd(
UIXComponentBase.java:711)
    at org.apache.myfaces.trinidad.render.CoreRenderer.encodeChild(
CoreRenderer.java:299)
    at
org.apache.myfaces.trinidadinternal.renderkit.core.xhtml.PanelGroupLayoutRenderer.encodeChild
(PanelGroupLayoutRenderer.java:188)
    at
org.apache.myfaces.trinidadinternal.renderkit.core.xhtml.PanelGroupLayoutRenderer._encodeChildren
(PanelGroupLayoutRenderer.java:154)
    at
org.apache.myfaces.trinidadinternal.renderkit.core.xhtml.PanelGroupLayoutRenderer.encodeAll
(PanelGroupLayoutRenderer.java:106)
    at org.apache.myfaces.trinidad.render.CoreRenderer.encodeEnd(
CoreRenderer.java:220)
    at org.apache.myfaces.trinidad.component.UIXComponentBase.encodeEnd(
UIXComponentBase.java:711)
    at org.apache.myfaces.trinidad.render.CoreRenderer.encodeChild(
CoreRenderer.java:299)
    at org.apache.myfaces.trinidad.render.CoreRenderer.encodeAllChildren(
CoreRenderer.java:316)
    at
org.apache.myfaces.trinidadinternal.renderkit.core.xhtml.PanelPartialRootRenderer.renderContent
(PanelPartialRootRenderer.java:64)
    at
org.apache.myfaces.trinidadinternal.renderkit.core.xhtml.BodyRenderer.renderContent
(BodyRenderer.java:139)
    at
org.apache.myfaces.trinidadinternal.renderkit.core.xhtml.PanelPartialRootRenderer.encodeAll
(PanelPartialRootRenderer.java:119)
    at
org.apache.myfaces.trinidadinternal.renderkit.core.xhtml.BodyRenderer.encodeAll
(BodyRenderer.java:79)
    at org.apache.myfaces.trinidad.render.CoreRenderer.encodeEnd(
CoreRenderer.java:220)
    at org.apache.myfaces.trinidad.component.UIXComponentBase.encodeEnd(
UIXComponentBase.java:711)
    at com.sun.facelets.tag.jsf.ComponentSupport.encodeRecursive(
ComponentSupport.java:252)
    at com.sun.facelets.tag.jsf.ComponentSupport.encodeRecursive(
ComponentSupport.java:249)
    at com.sun.facelets.tag.jsf.ComponentSupport.encodeRecursive(
ComponentSupport.java:249)
    at com.sun.facelets.FaceletViewHandler.renderView(
FaceletViewHandler.java:594)
    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
:132)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:140)


-- 
"Many men go fishing all of their lives without knowing it is not fish they
are after."

- Henry David Thoreau