title: Locate the code with error when not give in the error descreption
body: <p>I get this error in a JSF page, but I can not locate the error in my code to correct it. What can I do if the stack trace do not point to any source code of my own code?</p>
  
  <p>I have not entered or called a value 41.5 and can not find that value on search within the source code as well.</p>
  
  <pre><code>WARNING:   StandardWrapperValve[Faces Servlet]: Servlet.service() for servlet Faces Servlet threw exception
  java.lang.NumberFormatException: For input string: "41.5"
      at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
      at java.lang.Long.parseLong(Long.java:441)
      at java.lang.Long.valueOf(Long.java:540)
      at com.sun.el.lang.ELSupport.coerceToNumber(ELSupport.java:317)
      at com.sun.el.lang.ELSupport.coerceToNumber(ELSupport.java:296)
      at com.sun.el.lang.ELSupport.compare(ELSupport.java:103)
      at com.sun.el.parser.AstLessThan.getValue(AstLessThan.java:66)
      at com.sun.el.parser.AstAnd.getValue(AstAnd.java:63)
      at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:226)
      at org.jboss.weld.el.WeldValueExpression.getValue(WeldValueExpression.java:50)
      at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
      at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
      at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:462)
      at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1850)
      at com.sun.faces.facelets.component.RepeatRenderer.encodeChildren(RepeatRenderer.java:104)
      at com.sun.faces.facelets.component.UIRepeat.process(UIRepeat.java:527)
      at com.sun.faces.facelets.component.UIRepeat.encodeChildren(UIRepeat.java:990)
      at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:304)
      at com.sun.faces.renderkit.html_basic.GroupRenderer.encodeChildren(GroupRenderer.java:115)
      at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:894)
      at org.primefaces.renderkit.CoreRenderer.renderChild(CoreRenderer.java:70)
      at org.primefaces.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:57)
      at org.primefaces.component.panel.PanelRenderer.encodeContent(PanelRenderer.java:204)
      at org.primefaces.component.panel.PanelRenderer.encodeMarkup(PanelRenderer.java:121)
      at org.primefaces.component.panel.PanelRenderer.encodeEnd(PanelRenderer.java:58)
      at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:924)
      at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1863)
      at javax.faces.render.Renderer.encodeChildren(Renderer.java:176)
      at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:894)
      at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:304)
      at com.sun.faces.renderkit.html_basic.GroupRenderer.encodeChildren(GroupRenderer.java:115)
      at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:894)
      at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:304)
      at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185)
      at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129)
      at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:894)
      at org.primefaces.renderkit.CoreRenderer.renderChild(CoreRenderer.java:70)
      at org.primefaces.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:57)
      at org.primefaces.component.panel.PanelRenderer.encodeContent(PanelRenderer.java:204)
      at org.primefaces.component.panel.PanelRenderer.encodeMarkup(PanelRenderer.java:121)
      at org.primefaces.component.panel.PanelRenderer.encodeEnd(PanelRenderer.java:58)
      at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:924)
      at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1863)
      at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
      at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
      at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:443)
      at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
      at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
      at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
      at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
      at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
      at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
      at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:344)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
      at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:70)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:316)
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
      at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
      at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
      at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
      at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
      at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
      at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
      at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
      at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
      at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
      at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
      at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
      at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
      at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
      at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
      at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
      at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
      at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
      at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
      at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
      at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
      at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
      at java.lang.Thread.run(Thread.java:744)
  </code></pre>
  
  <p>JSF Segment that gives rise to error</p>
  
  <pre><code>                        &lt;p:panel header="Microbiology"    rendered="#{patientReportController.currentPatientReport.patientInvestigation.investigation.reportType eq 'Microbiology'}" &gt;
  
                              &lt;p:dataTable id="tblMicVals" value="#{patientReportController.currentPatientReport.patientReportItemOfValueType}"  var="pv"  &gt;
  
                                  &lt;p:column &gt;
                                      &lt;h:outputLabel value="#{pv.investigationItem.name}" rendered="#{pv.investigationItem.ixItemType eq 'Value'}"&gt;&lt;/h:outputLabel&gt;
                                  &lt;/p:column&gt;
  
                                  &lt;p:column &gt;
                                      &lt;h:panelGroup rendered="#{pv.investigationItem.ixItemType eq 'Value'}"&gt;
                                          &lt;h:panelGroup rendered="#{pv.investigationItem.ixItemValueType eq 'Memo'}" &gt;
                                              &lt;p:inputTextarea id="txtMicMemoVal"   style="min-width: 200px;" completeMethod="#{investigationItemValueController.completeValues}"  &gt;
                                              &lt;/p:inputTextarea&gt;
                                              &lt;p:watermark  value="#{pv.lobValue}" for="txtMicMemoVal" /&gt;
                                          &lt;/h:panelGroup&gt;
                                          &lt;h:panelGroup rendered="#{pv.investigationItem.ixItemValueType eq 'Varchar'}"&gt;
                                              &lt;p:selectOneMenu id="cmbMicStrVal" value="#{patientReportController.strEnterVal}" editable="true"  style="min-width: 300px!important;" &gt;
                                                  &lt;f:selectItem itemLabel="SENSITIVE" itemValue="SENSITIVE" &gt;&lt;/f:selectItem&gt;
                                                  &lt;f:selectItem itemLabel="Resistant" itemValue="Resistant" &gt;&lt;/f:selectItem&gt;
                                                  &lt;f:selectItem itemLabel="Intermediate" itemValue="Intermediate" &gt;&lt;/f:selectItem&gt;
                                                  &lt;f:ajax event="change"  execute="@this" listener="#{patientReportController.saveStrVal(pv.id) }" &gt;&lt;/f:ajax&gt;
                                              &lt;/p:selectOneMenu&gt;
                                              &lt;p:watermark  value="#{pv.strValue}" for="cmbMicStrVal" /&gt;
                                          &lt;/h:panelGroup&gt;
  
  
                                      &lt;/h:panelGroup&gt;
  
  
  
  
  
  
                                  &lt;/p:column&gt;
                              &lt;/p:dataTable&gt;
                          &lt;/p:panel&gt;
  </code></pre>
  
  <p>After the answer by BalusC, which preciously lead me to the place of error, I could identify the cause. As he mentioned, inside expression language, I have used,  ls to compare a string value.</p>
  
  <p>This is the exact place. prv.investigationItem.cssTop is a String. I have used it with lt.</p>
  
  <pre><code>&lt;h:panelGroup rendered="#{prv.investigationItem.ixItemType eq 'Value' and prv.investigationItem.ixItemValueType eq 'Memo' and prv.investigationItem.retired eq false and prv.lobValue ne '' and prv.lobValue ne null and prv.investigationItem.cssTop lt 50 }" &gt;
  </code></pre>