Tomcat 7 can't find my class throws javax.el.ELException: java.lang.NoClassDefFoundError

Question

My web app runs tomcat 7, myfaces, primefaces.

I have a problem on my production m/c that I am not able to replicate on development environment even though the exact code and libraries are loaded on both the machines. The only difference is the tomcat subversion, dev has tomcat7.0.35 and prod has tomcat7.0.40

javax.servlet.ServletException: javax.el.ELException: java.lang.NoClassDefFoundError: Could not initialize class com.myapps.util.UIStringUtil
javax.faces.webapp.FacesServlet.service(FacesServlet.java:229)
com.myapps.util.LoginFilter.doFilter(LoginFilter.java:56) **root cause** java.lang.NoClassDefFoundError: Could not initialize class com.myapps.util.UIStringUtil
com.myapps.bean.UserAuthBean.login(UserAuthBean.java:106)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:597)
org.apache.el.parser.AstValue.invoke(AstValue.java:278)
org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:274)
org.apache.myfaces.view.facelets.el.ContextAwareTagMethodExpression.invoke(ContextAwareTagMethodExpression.java:96)
org.apache.myfaces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:68)
javax.faces.component.UICommand.broadcast(UICommand.java:120)
javax.faces.component.UIViewRoot._broadcastAll(UIViewRoot.java:1028)
javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:286)
javax.faces.component.UIViewRoot._process(UIViewRoot.java:1375)
javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:752)
org.apache.myfaces.lifecycle.InvokeApplicationExecutor.execute(InvokeApplicationExecutor.java:38)
org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:170)
org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:117)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:197)
com.myapps.util.LoginFilter.doFilter(LoginFilter.java:56)

I am not sure why this is happening. I am curious why this is being thrown as a javax.el.Elexception, where was this is being thrown from with in java bean code. The exact line of code where this is happening is (UserAuthBean.java:106)

context.addMessage(null, new FacesMessage(FacesMessage.SEVERITY_INFO, 
                    UIStringUtil.getUIString("msgKey"), 
                    UIStringUtil.getUIString("msgKey")));

UIStringUtil class has static variables and methods that help read data from resource bundles.

As I mentioned earlier, this is only happening on the production box and we are not able to reproduce it on the development box.

Please provide some help here.

Answer 1

It's thrown as an ELException because it happened during executing some EL expression.

You should be looking at the root cause of the exception to learn about the root cause of the exception. Look further down in the stack trace to find the root cause. The first is already present in the incomplete stacktrace you posted:

java.lang.NoClassDefFoundError: Could not initialize class com.myapps.util.UIStringUtil

This basically means that loading of the class as done by Java under the covers as follows

Class.forName("com.myapps.util.UIStringUtil");

has failed with an exception. If you're absolutely positive that the class is present in the runtime classpath, then that can only mean that any of the static variables or initializer blocks of the class has thrown an exception. Loading a class namely initializes all static variables and executes all static initilaizer blocks (haven't you ever wondered how those JDBC drivers work?).

That exception should in turn be visible as the bottommost root cause in the stack trace, after the java.lang.NoClassDefFoundError cause. Perhaps a rather self-explaining java.lang.NullPointerException?