ClassNotFoundException：org.slf4j.LoggerFactory Maven

Question

I'm trying to run a .war file with tomcat on a server. Everytime I startup tomcat it should set a timer, which runs the init()-method of the .war file once in a week. I'm doing this with the CronTrigger from Quartz. The JobBuilder calls the class HelloJob, in which (when running) a huge excel table gets created.

public class CronTrigger implements Servlet

{    
    public void init(ServletConfig arg0) throws ServletException {

        JobDetail job = JobBuilder.newJob(HelloJob.class).withIdentity("Batch Validation Trigger", "group1").build();

        Trigger trigger = TriggerBuilder.newTrigger().withIdentity("Batch Validation Trigger", "group1").withSchedule(CronScheduleBuilder.cronSchedule("0 45 14 ? * TUE")).build();
        Logger root = (Logger)LoggerFactory.getLogger(CronTrigger.class);
        root.isDebugEnabled();
        //schedule it
        Scheduler scheduler = null;
        try {
            scheduler = new StdSchedulerFactory().getScheduler();
        } catch (SchedulerException e) {
            e.printStackTrace();
        }
        try {
            scheduler.start();
        } catch (SchedulerException e1) {
            e1.printStackTrace();
        }
        try {
            scheduler.scheduleJob(job, trigger);
        } catch (SchedulerException e2) {
            e2.printStackTrace();
        }
    }
}    

My web.xml:

<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <display-name>WOQC</display-name>
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
      <servlet>
    <servlet-name>CronTrigger</servlet-name>
    <servlet-class>timer.CronTrigger</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>CronTrigger</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.jsf</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.faces</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>/faces/*</url-pattern>
    </servlet-mapping>
    <filter>
        <filter-name>PrimeFaces FileUpload Filter</filter-name>
        <filter-class>org.primefaces.webapp.filter.FileUploadFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>PrimeFaces FileUpload Filter</filter-name>
        <servlet-name>Faces Servlet</servlet-name>
    </filter-mapping>
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
    </welcome-file-list>
</web-app>

When I try to run it, it returns one error and one exception: NoClassDefFoundError:

SEVERE: StandardWrapper.Throwable
    java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory
        at timer.CronTrigger.init(CronTrigger.java:48)
        at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284)
        at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197)
        at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087)
        at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5231)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5518)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1575)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1565)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)
    Caused by: java.lang.ClassNotFoundException: org.slf4j.LoggerFactory
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
        ... 13 more

ClassNotFoundException:

SEVERE: Servlet /WO threw load() exception
java.lang.ClassNotFoundException: org.slf4j.LoggerFactory
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
    at timer.CronTrigger.init(CronTrigger.java:48)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5231)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5518)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1575)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1565)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

I already have read the questions about this exception and added slf4j-nop-1.7.7.jar and slf4j-api-1.7.7.jar to the classpath. I know that the problem belongs to the implementation of the LoggerFactory, but I couldn't find a good example to solve my problem. If you have any idea, please respond.

Thanks in advance!

Answer 1

ClassNotFoundException prompts when third party libraries are not identified by the IDE itself. You should add you jars files (third party libraries) into WEB-INF/lib folder. Now it should function properly.

Answer 2

add your slf4j.jar in lib directory.

War file structure is as follows

WebContent
    --- WEB-INF
         ----web.xml (Deployment Descriptor)
         ---- lib 
                --- Add your libraries here i.e. slf4j*.jar and others