NoClassDefFoundError in Eclipse when adding project in build path

Question

I am receiving an NoClassDefFoundError in Eclipse when I try to run my project.

My Project looks like this:

JavaProject: BulkAdmin
   - src
      - com.mycompany.bulkadmin.SDK.util
         - Login.java

Dynamic Web Project: JSPTesting
   - src
      - com.mycompany.bulkadmin.jspController
         - Controller.java
   - WebContent
      - index.html
      - execute.jsp

This is the control flow:

1. index.html loads
2. index.html has a form that redirects to execute.jsp
3. execute.jsp takes the info returned in the form and makes a static call to Login.java
4. execute.jsp prints the results of the call

Controller.java uses Login.java. I was receiving compilation errors. To resolve them I did this:

1. Right click on JSPTesting -> properties
2. Choose java build path on the left bar
3. Choose projects tab
4. Click add
5. Choose BulkAdmin (Project)

I am not sure why but now when I am getting a NoClassDefFoundError. I have done some googling. I think that this means that I have messed up my classpath somehow but I am not sure how to resolve this.

java.lang.NoClassDefFoundError: com/myCompany/bulkadmin/SDK/util/Login
    at com.myCompany.bulkadmin.jspController.Controller.process(Controller.java:44)
    at org.apache.jsp.execute_jsp._jspService(execute_jsp.java:63)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:321)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:257)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:873)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
    at java.lang.Thread.run(Thread.java:595)

Other information:

• I am using tomcat (in Eclipse) as my server
• The exception shows up in the browser and the eclipse console
• execute.jsp is a JSP

It seems like there are many similar questions to this on SO. I have read about 15 of them and tried various things however I think that my question has a different solution. I can provide more information.

Answer 1

Rightclick your dynamic web project, go to Properties > Deployment Assembly and add the dependent projects there. This way they will end up as JAR in /WEB-INF/lib, exactly there where you want it to be.

In Eclipse versions older than 3.5 you need to go to Properties > Java EE Module Dependencies.

See also:

• ClassNotFoundException when using User Libraries in Eclipse build path
• Difference between Deployment Assembly and J2EE Module Dependencies in Eclipse

Answer 2

The NoClassDefFoundError indicates that a class that was available during compilation is no longer available at runtime. Your problem is that the com/myCompany/bulkadmin/cSDK/util/Login class is available in the compilation classpath (in Eclipse via the Project reference you added to the build path) but not in the runtime classpath (Tomcat, which has no idea how to find this class).

You need to add the BulkAdmin project to the web-app class path when deployed on Tomcat as well.

One way to do this would be to export the BulkAdmin project as a JAR and put it into the WEB-INF/lib directory of your JSPTesting project.