Eclipse warning: XXXXXXXXXXX.jar will not be exported or published. Runtime ClassNotFoundExceptions may result

Question

I keep getting the following error after I put the required files in my build path on Eclipse. I am working on a Spring MVC Hello World Application and using Eclipse Helios for Java EE developers:

Jan 16, 2012 1:25:42 PM org.apache.catalina.core.StandardContext loadOnStartup SEVERE: Servlet /SpringMVCTutorial threw load() exception java.lang.ClassNotFoundException: org.springframework.web.servlet.DispatcherServlet     at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1676)     at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1521)     at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:415)     at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:397)     at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:118)     at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1062)     at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1010)     at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4957)     at org.apache.catalina.core.StandardContext$3.call(StandardContext.java:5284)     at org.apache.catalina.core.StandardContext$3.call(StandardContext.java:5279)     at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)     at java.util.concurrent.FutureTask.run(Unknown Source)     at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)     at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)     at java.lang.Thread.run(Unknown Source) 

I have tried right-clicking the server and clicking "clean". I right click the application, click "Build Path" the "Configure Build Path" and put the right JAR files in the library; however, it still doesn't acknowledge them as dependencies. What am I missing?

I have tried the advice presented here:

1. Right-click on your Web project
2. Click 'Properties'
3. Select 'Java EE Module Dependencies'
4. Click the 'Web Libraries' tab
5. Add external JARs (if the JAR is outside of your project). An entry will be added under Jar/Module, make sure you click on the checkbox (checked).

The problem is that when I select "Click Properties", I do not have the option of clicking Java EE Module dependencies, as it doesn't appear. I downloaded any extra Java EE tools and still can't find it.

Answer 1

In order to get it to work right, I have to "drop and drag" the files that I want in my classpath/dependencies into my the WEB-INF/lib folder. It works this way.

For some reason, when I try to do it the right way

Build path → Configure build path → External jars

it just doesn't take them.

The trick is that I have to put the files int my Web App Libraries folder and the only way to do that (that I can see) is to "click and drop" into my WEB-INF/lib folder. In this way, it automatically shows up in my Web App Libraries.

Answer 2

When adding new jar files, I got two messages on Eclipse's Problems Tab: one error and one warning. I only solved this problem when combining all previous solutions with an extra step. Here's how I solved it:

1. "Drag and drop" the files that I want in my classpath/dependencies into my WEB-INF/lib/ folder;
2. Right-click on your project in the Package Explorer tab, and build path --> configure build path --> external jars, adding the desired files;
3. Restarted Eclipse;
4. Select Project --> Clean…. My system is configured to build automatically, so after this step, the error message was gone, but the warning XXXXXXXXXXX.jar will not be exported or published. Runtime ClassNotFoundExceptions may result remained;
5. Right-click on warning message --> Quick Fix;
6. Select the option Mark the associated raw classpath entry as a publish/export dependency. (in the following figure)